From beab6b009ef45d1d8e62943caa4bceb7a04f0c16 Mon Sep 17 00:00:00 2001
From: Brad Jorsch <bjorsch@wikimedia.org>
Date: Fri, 16 Jan 2015 14:00:07 -0500
Subject: [PATCH] Change API result data structure to be cleaner in new formats

Nothing in this patch should result in changed output for format=json or
format=php except as noted in RELEASE-NOTES-1.25, and changed output for
format=xml should be similar or cosmetic. However, other code accessing
the result data directly may need to be updated.

Bug: T87053
Bug: T12887
Change-Id: I3500708965cb8869b5aed1543381aad208dadd13
---
 RELEASE-NOTES-1.25                            |  7 ++
 includes/api/ApiBlock.php                     | 28 ++----
 includes/api/ApiContinuationManager.php       |  2 +-
 includes/api/ApiEditPage.php                  |  4 +-
 includes/api/ApiExpandTemplates.php           | 21 ++---
 includes/api/ApiImageRotate.php               |  4 +-
 includes/api/ApiImport.php                    |  2 +-
 includes/api/ApiManageTags.php                |  4 +-
 includes/api/ApiMove.php                      | 22 ++---
 includes/api/ApiOpenSearch.php                |  1 +
 includes/api/ApiPageSet.php                   |  2 +-
 includes/api/ApiParamInfo.php                 | 16 ++--
 includes/api/ApiParse.php                     | 91 ++++++-------------
 includes/api/ApiProtect.php                   |  2 +-
 includes/api/ApiPurge.php                     |  4 +-
 includes/api/ApiQuery.php                     | 18 ++--
 includes/api/ApiQueryAllCategories.php        |  4 +-
 includes/api/ApiQueryAllLinks.php             |  4 +-
 includes/api/ApiQueryAllMessages.php          |  6 +-
 includes/api/ApiQueryAllUsers.php             |  2 +-
 includes/api/ApiQueryBacklinks.php            |  4 +-
 includes/api/ApiQueryBacklinksprop.php        |  4 +-
 includes/api/ApiQueryBlocks.php               | 32 ++-----
 includes/api/ApiQueryCategories.php           |  4 +-
 includes/api/ApiQueryCategoryInfo.php         |  4 +-
 includes/api/ApiQueryCategoryMembers.php      |  4 +-
 includes/api/ApiQueryDeletedrevs.php          | 14 +--
 includes/api/ApiQueryDuplicateFiles.php       |  6 +-
 includes/api/ApiQueryExtLinksUsage.php        |  4 +-
 includes/api/ApiQueryFileRepoInfo.php         |  2 +
 includes/api/ApiQueryFilearchive.php          |  8 +-
 includes/api/ApiQueryIWBacklinks.php          |  2 +-
 includes/api/ApiQueryImageInfo.php            | 12 ++-
 includes/api/ApiQueryInfo.php                 | 18 ++--
 includes/api/ApiQueryLangBacklinks.php        |  2 +-
 includes/api/ApiQueryLogEvents.php            | 17 ++--
 includes/api/ApiQueryPageProps.php            |  1 +
 includes/api/ApiQueryPagesWithProp.php        |  4 +-
 includes/api/ApiQueryPrefixSearch.php         |  2 +-
 includes/api/ApiQueryQueryPage.php            |  4 +-
 includes/api/ApiQueryRecentChanges.php        | 42 +++------
 includes/api/ApiQueryRevisionsBase.php        | 28 +++---
 includes/api/ApiQuerySiteinfo.php             | 79 ++++++----------
 includes/api/ApiQueryTags.php                 | 10 +-
 includes/api/ApiQueryTokens.php               |  4 +-
 includes/api/ApiQueryUserContributions.php    | 24 ++---
 includes/api/ApiQueryUserInfo.php             | 17 +++-
 includes/api/ApiQueryUsers.php                | 15 +--
 includes/api/ApiQueryWatchlist.php            | 33 +++----
 includes/api/ApiResult.php                    |  6 +-
 includes/api/ApiSetNotificationTimestamp.php  | 14 +--
 includes/api/ApiTokens.php                    |  4 +-
 includes/api/ApiWatch.php                     |  4 +-
 .../api/ApiContinuationManagerTest.php        |  2 +-
 .../includes/api/ApiErrorFormatterTest.php    |  8 ++
 tests/phpunit/includes/api/ApiResultTest.php  | 50 +++++++---
 .../includes/api/format/ApiFormatTestBase.php |  1 +
 .../api/query/ApiQueryContinue2Test.php       |  2 +-
 .../api/query/ApiQueryContinueTest.php        | 16 ++--
 59 files changed, 345 insertions(+), 406 deletions(-)

diff --git a/RELEASE-NOTES-1.25 b/RELEASE-NOTES-1.25
index 13b01d9446..530a80445c 100644
--- a/RELEASE-NOTES-1.25
+++ b/RELEASE-NOTES-1.25
@@ -268,6 +268,9 @@ production.
     as comma-separated lists.
   * merge events use new-style formatting.
   * delete/event and delete/revision events use new-style formatting.
+* The root node and various other nodes will now always be an object in formats
+  such as json that distinguish between arrays and objects.
+  * Except for action=opensearch where the spec requires an array.
 
 === Action API internal changes in 1.25 ===
 * ApiHelp has been rewritten to support i18n and paginated HTML output.
@@ -316,6 +319,10 @@ production.
   metadata isn't set.
 * (T35235) LogFormatter subclasses are now responsible for formatting log event
   parameters for the API.
+* Many modules have changed result data formats. While this shouldn't affect
+  clients not using the experimental formatversion=2015, code using
+  ApiResult::getResultData() and not using ApiResult::transformForBC() may need
+  updating.
 * The following methods have been deprecated and may be removed in a future
   release:
   * ApiBase::getDescription
diff --git a/includes/api/ApiBlock.php b/includes/api/ApiBlock.php
index 72aee32118..26b5f0e56c 100644
--- a/includes/api/ApiBlock.php
+++ b/includes/api/ApiBlock.php
@@ -113,27 +113,13 @@ class ApiBlock extends ApiBase {
 		}
 
 		$res['reason'] = $params['reason'];
-		if ( $params['anononly'] ) {
-			$res['anononly'] = '';
-		}
-		if ( $params['nocreate'] ) {
-			$res['nocreate'] = '';
-		}
-		if ( $params['autoblock'] ) {
-			$res['autoblock'] = '';
-		}
-		if ( $params['noemail'] ) {
-			$res['noemail'] = '';
-		}
-		if ( $params['hidename'] ) {
-			$res['hidename'] = '';
-		}
-		if ( $params['allowusertalk'] ) {
-			$res['allowusertalk'] = '';
-		}
-		if ( $params['watchuser'] ) {
-			$res['watchuser'] = '';
-		}
+		$res['anononly'] = $params['anononly'];
+		$res['nocreate'] = $params['nocreate'];
+		$res['autoblock'] = $params['autoblock'];
+		$res['noemail'] = $params['noemail'];
+		$res['hidename'] = $params['hidename'];
+		$res['allowusertalk'] = $params['allowusertalk'];
+		$res['watchuser'] = $params['watchuser'];
 
 		$this->getResult()->addValue( null, $this->getModuleName(), $res );
 	}
diff --git a/includes/api/ApiContinuationManager.php b/includes/api/ApiContinuationManager.php
index dea1cf408e..354f4e7de1 100644
--- a/includes/api/ApiContinuationManager.php
+++ b/includes/api/ApiContinuationManager.php
@@ -231,7 +231,7 @@ class ApiContinuationManager {
 				ApiResult::ADD_ON_TOP | ApiResult::NO_SIZE_CHECK );
 		}
 		if ( $batchcomplete ) {
-			$result->addValue( null, 'batchcomplete', '',
+			$result->addValue( null, 'batchcomplete', true,
 				ApiResult::ADD_ON_TOP | ApiResult::NO_SIZE_CHECK );
 		}
 	}
diff --git a/includes/api/ApiEditPage.php b/includes/api/ApiEditPage.php
index 601c64cd26..0dee147d06 100644
--- a/includes/api/ApiEditPage.php
+++ b/includes/api/ApiEditPage.php
@@ -490,7 +490,7 @@ class ApiEditPage extends ApiBase {
 				$this->dieStatus( $status );
 
 			case EditPage::AS_SUCCESS_NEW_ARTICLE:
-				$r['new'] = '';
+				$r['new'] = true;
 				// fall-through
 
 			case EditPage::AS_SUCCESS_UPDATE:
@@ -500,7 +500,7 @@ class ApiEditPage extends ApiBase {
 				$r['contentmodel'] = $titleObj->getContentModel();
 				$newRevId = $articleObject->getLatest();
 				if ( $newRevId == $oldRevId ) {
-					$r['nochange'] = '';
+					$r['nochange'] = true;
 				} else {
 					$r['oldrevid'] = intval( $oldRevId );
 					$r['newrevid'] = intval( $newRevId );
diff --git a/includes/api/ApiExpandTemplates.php b/includes/api/ApiExpandTemplates.php
index 5c7717f919..6d064eb230 100644
--- a/includes/api/ApiExpandTemplates.php
+++ b/includes/api/ApiExpandTemplates.php
@@ -96,9 +96,8 @@ class ApiExpandTemplates extends ApiBase {
 				$retval['parsetree'] = $xml;
 			} else {
 				// the old way
-				$xml_result = array();
-				ApiResult::setContentValue( $xml_result, 'xml', $xml );
-				$result->addValue( null, 'parsetree', $xml_result );
+				$result->addValue( null, 'parsetree', $xml );
+				$result->addValue( null, ApiResult::META_BC_SUBELEMENTS, array( 'parsetree' ) );
 			}
 		}
 
@@ -129,19 +128,13 @@ class ApiExpandTemplates extends ApiBase {
 				if ( isset( $prop['properties'] ) ) {
 					$properties = $wgParser->getOutput()->getProperties();
 					if ( $properties ) {
-						$properties_result = array();
-						foreach ( $properties as $name => $value ) {
-							$entry = array();
-							$entry['name'] = $name;
-							ApiResult::setContentValue( $entry, 'value', $value );
-							$properties_result[] = $entry;
-						}
-						ApiResult::setIndexedTagName( $properties_result, 'property' );
-						$retval['properties'] = $properties_result;
+						ApiResult::setArrayType( $properties, 'BCkvp', 'name' );
+						ApiResult::setIndexedTagName( $properties, 'property' );
+						$retval['properties'] = $properties;
 					}
 				}
-				if ( isset( $prop['volatile'] ) && $frame->isVolatile() ) {
-					$retval['volatile'] = '';
+				if ( isset( $prop['volatile'] ) ) {
+					$retval['volatile'] = $frame->isVolatile();
 				}
 				if ( isset( $prop['ttl'] ) && $frame->getTTL() !== null ) {
 					$retval['ttl'] = $frame->getTTL();
diff --git a/includes/api/ApiImageRotate.php b/includes/api/ApiImageRotate.php
index 7b99921de7..865d39fafe 100644
--- a/includes/api/ApiImageRotate.php
+++ b/includes/api/ApiImageRotate.php
@@ -42,7 +42,7 @@ class ApiImageRotate extends ApiBase {
 				$v = $val;
 			}
 			if ( $flag !== null ) {
-				$v[$flag] = '';
+				$v[$flag] = true;
 			}
 			$result[] = $v;
 		}
@@ -71,7 +71,7 @@ class ApiImageRotate extends ApiBase {
 			$r['id'] = $title->getArticleID();
 			ApiQueryBase::addTitleInfo( $r, $title );
 			if ( !$title->exists() ) {
-				$r['missing'] = '';
+				$r['missing'] = true;
 			}
 
 			$file = wfFindFile( $title, array( 'latest' => true ) );
diff --git a/includes/api/ApiImport.php b/includes/api/ApiImport.php
index 9d76a46176..2e87d22da0 100644
--- a/includes/api/ApiImport.php
+++ b/includes/api/ApiImport.php
@@ -155,7 +155,7 @@ class ApiImportReporter extends ImportReporter {
 		if ( $title === null ) {
 			# Invalid or non-importable title
 			$r['title'] = $pageInfo['title'];
-			$r['invalid'] = '';
+			$r['invalid'] = true;
 		} else {
 			ApiQueryBase::addTitleInfo( $r, $title );
 			$r['revisions'] = intval( $successCount );
diff --git a/includes/api/ApiManageTags.php b/includes/api/ApiManageTags.php
index 80317d3576..240d35062a 100644
--- a/includes/api/ApiManageTags.php
+++ b/includes/api/ApiManageTags.php
@@ -49,8 +49,8 @@ class ApiManageTags extends ApiBase {
 		if ( !$status->isGood() ) {
 			$ret['warnings'] = $this->getErrorFormatter()->arrayFromStatus( $status, 'warning' );
 		}
-		if ( $status->value !== null ) {
-			$ret['success'] = '';
+		$ret['success'] = $status->value !== null;
+		if ( $ret['success'] ) {
 			$ret['logid'] = $status->value;
 		}
 		$result->addValue( null, $this->getModuleName(), $ret );
diff --git a/includes/api/ApiMove.php b/includes/api/ApiMove.php
index 0db18e7168..e42958bf5a 100644
--- a/includes/api/ApiMove.php
+++ b/includes/api/ApiMove.php
@@ -83,18 +83,14 @@ class ApiMove extends ApiBase {
 			'reason' => $params['reason']
 		);
 
-		if ( $fromTitle->exists() ) {
-			//NOTE: we assume that if the old title exists, it's because it was re-created as
-			// a redirect to the new title. This is not safe, but what we did before was
-			// even worse: we just determined whether a redirect should have been created,
-			// and reported that it was created if it should have, without any checks.
-			// Also note that isRedirect() is unreliable because of bug 37209.
-			$r['redirectcreated'] = '';
-		}
+		//NOTE: we assume that if the old title exists, it's because it was re-created as
+		// a redirect to the new title. This is not safe, but what we did before was
+		// even worse: we just determined whether a redirect should have been created,
+		// and reported that it was created if it should have, without any checks.
+		// Also note that isRedirect() is unreliable because of bug 37209.
+		$r['redirectcreated'] = $fromTitle->exists();
 
-		if ( $toTitleExists ) {
-			$r['moveoverredirect'] = '';
-		}
+		$r['moveoverredirect'] = $toTitleExists;
 
 		// Move the talk page
 		if ( $params['movetalk'] && $fromTalk->exists() && !$fromTitle->isTalkPage() ) {
@@ -103,9 +99,7 @@ class ApiMove extends ApiBase {
 			if ( $status->isOK() ) {
 				$r['talkfrom'] = $fromTalk->getPrefixedText();
 				$r['talkto'] = $toTalk->getPrefixedText();
-				if ( $toTalkExists ) {
-					$r['talkmoveoverredirect'] = '';
-				}
+				$r['talkmoveoverredirect'] = $toTalkExists;
 			} else {
 				// We're not gonna dieUsage() on failure, since we already changed something
 				$error = $this->getErrorFromStatus( $status );
diff --git a/includes/api/ApiOpenSearch.php b/includes/api/ApiOpenSearch.php
index 33790f9285..8c03dceeff 100644
--- a/includes/api/ApiOpenSearch.php
+++ b/includes/api/ApiOpenSearch.php
@@ -212,6 +212,7 @@ class ApiOpenSearch extends ApiBase {
 		switch ( $this->getFormat() ) {
 			case 'json':
 				// http://www.opensearch.org/Specifications/OpenSearch/Extensions/Suggestions/1.1
+				$result->addArrayType( null, 'array' );
 				$result->addValue( null, 0, strval( $search ) );
 				$terms = array();
 				$descriptions = array();
diff --git a/includes/api/ApiPageSet.php b/includes/api/ApiPageSet.php
index 02a25fe82f..e6f218d62b 100644
--- a/includes/api/ApiPageSet.php
+++ b/includes/api/ApiPageSet.php
@@ -96,7 +96,7 @@ class ApiPageSet extends ApiBase {
 				$v = $val;
 			}
 			if ( $flag !== null ) {
-				$v[$flag] = '';
+				$v[$flag] = true;
 			}
 			$result[] = $v;
 		}
diff --git a/includes/api/ApiParamInfo.php b/includes/api/ApiParamInfo.php
index bb661b2139..25069d9db7 100644
--- a/includes/api/ApiParamInfo.php
+++ b/includes/api/ApiParamInfo.php
@@ -216,7 +216,7 @@ class ApiParamInfo extends ApiBase {
 		$this->formatHelpMessages( $ret, 'description', $module->getFinalDescription() );
 
 		foreach ( $module->getHelpFlags() as $flag ) {
-			$ret[$flag] = '';
+			$ret[$flag] = true;
 		}
 
 		$ret['helpurls'] = (array)$module->getHelpUrls();
@@ -265,12 +265,10 @@ class ApiParamInfo extends ApiBase {
 				$this->formatHelpMessages( $item, 'description', $paramDesc[$name], true );
 			}
 
-			if ( !empty( $settings[ApiBase::PARAM_REQUIRED] ) ) {
-				$item['required'] = '';
-			}
+			$item['required'] = !empty( $settings[ApiBase::PARAM_REQUIRED] );
 
 			if ( !empty( $settings[ApiBase::PARAM_DEPRECATED] ) ) {
-				$item['deprecated'] = '';
+				$item['deprecated'] = true;
 			}
 
 			if ( $name === 'token' && $module->needsToken() ) {
@@ -307,8 +305,8 @@ class ApiParamInfo extends ApiBase {
 				}
 			}
 
-			if ( !empty( $settings[ApiBase::PARAM_ISMULTI] ) ) {
-				$item['multi'] = '';
+			$item['multi'] = !empty( $settings[ApiBase::PARAM_ISMULTI] );
+			if ( $item['multi'] ) {
 				$item['limit'] = $this->getMain()->canApiHighLimits() ?
 					ApiBase::LIMIT_SML2 :
 					ApiBase::LIMIT_SML1;
@@ -317,14 +315,14 @@ class ApiParamInfo extends ApiBase {
 			}
 
 			if ( !empty( $settings[ApiBase::PARAM_ALLOW_DUPLICATES] ) ) {
-				$item['allowsduplicates'] = '';
+				$item['allowsduplicates'] = true;
 			}
 
 			if ( isset( $settings[ApiBase::PARAM_TYPE] ) ) {
 				if ( $settings[ApiBase::PARAM_TYPE] === 'submodule' ) {
 					$item['type'] = $module->getModuleManager()->getNames( $name );
 					sort( $item['type'] );
-					$item['submodules'] = '';
+					$item['submodules'] = true;
 				} else {
 					$item['type'] = $settings[ApiBase::PARAM_TYPE];
 				}
diff --git a/includes/api/ApiParse.php b/includes/api/ApiParse.php
index 267bced766..fc004cfdbe 100644
--- a/includes/api/ApiParse.php
+++ b/includes/api/ApiParse.php
@@ -225,21 +225,17 @@ class ApiParse extends ApiBase {
 			if ( $params['onlypst'] ) {
 				// Build a result and bail out
 				$result_array = array();
-				$result_array['text'] = array();
-				ApiResult::setContentValue( $result_array['text'], 'text', $this->pstContent->serialize( $format ) );
+				$result_array['text'] = $this->pstContent->serialize( $format );
+				$result_array[ApiResult::META_BC_SUBELEMENTS][] = 'text';
 				if ( isset( $prop['wikitext'] ) ) {
-					$result_array['wikitext'] = array();
-					ApiResult::setContentValue( $result_array['wikitext'], 'wikitext', $this->content->serialize( $format ) );
+					$result_array['wikitext'] = $this->content->serialize( $format );
+					$result_array[ApiResult::META_BC_SUBELEMENTS][] = 'wikitext';
 				}
 				if ( !is_null( $params['summary'] ) ||
 					( !is_null( $params['sectiontitle'] ) && $this->section === 'new' )
 				) {
-					$result_array['parsedsummary'] = array();
-					ApiResult::setContentValue(
-						$result_array['parsedsummary'],
-						'parsedsummary',
-						$this->formatSummary( $titleObj, $params )
-					);
+					$result_array['parsedsummary'] = $this->formatSummary( $titleObj, $params );
+					$result_array[ApiResult::META_BC_SUBELEMENTS][] = 'parsedsummary';
 				}
 
 				$result->addValue( null, $this->getModuleName(), $result_array );
@@ -272,19 +268,15 @@ class ApiParse extends ApiBase {
 		}
 
 		if ( isset( $prop['text'] ) ) {
-			$result_array['text'] = array();
-			ApiResult::setContentValue( $result_array['text'], 'text', $p_result->getText() );
+			$result_array['text'] = $p_result->getText();
+			$result_array[ApiResult::META_BC_SUBELEMENTS][] = 'text';
 		}
 
 		if ( !is_null( $params['summary'] ) ||
 			( !is_null( $params['sectiontitle'] ) && $this->section === 'new' )
 		) {
-			$result_array['parsedsummary'] = array();
-			ApiResult::setContentValue(
-				$result_array['parsedsummary'],
-				'parsedsummary',
-				$this->formatSummary( $titleObj, $params )
-			);
+			$result_array['parsedsummary'] = $this->formatSummary( $titleObj, $params );
+			$result_array[ApiResult::META_BC_SUBELEMENTS][] = 'parsedsummary';
 		}
 
 		if ( isset( $prop['langlinks'] ) ) {
@@ -307,9 +299,8 @@ class ApiParse extends ApiBase {
 			$result_array['categories'] = $this->formatCategoryLinks( $p_result->getCategories() );
 		}
 		if ( isset( $prop['categorieshtml'] ) ) {
-			$categoriesHtml = $this->categoriesHtml( $p_result->getCategories() );
-			$result_array['categorieshtml'] = array();
-			ApiResult::setContentValue( $result_array['categorieshtml'], 'categorieshtml', $categoriesHtml );
+			$result_array['categorieshtml'] = $this->categoriesHtml( $p_result->getCategories() );
+			$result_array[ApiResult::META_BC_SUBELEMENTS][] = 'categorieshtml';
 		}
 		if ( isset( $prop['links'] ) ) {
 			$result_array['links'] = $this->formatLinks( $p_result->getLinks() );
@@ -349,12 +340,8 @@ class ApiParse extends ApiBase {
 			}
 
 			if ( isset( $prop['headhtml'] ) ) {
-				$result_array['headhtml'] = array();
-				ApiResult::setContentValue(
-					$result_array['headhtml'],
-					'headhtml',
-					$context->getOutput()->headElement( $context->getSkin() )
-				);
+				$result_array['headhtml'] = $context->getOutput()->headElement( $context->getSkin() );
+				$result_array[ApiResult::META_BC_SUBELEMENTS][] = 'headhtml';
 			}
 		}
 
@@ -366,11 +353,8 @@ class ApiParse extends ApiBase {
 		}
 
 		if ( isset( $prop['indicators'] ) ) {
-			foreach ( $p_result->getIndicators() as $name => $content ) {
-				$indicator = array( 'name' => $name );
-				ApiResult::setContentValue( $indicator, 'content', $content );
-				$result_array['indicators'][] = $indicator;
-			}
+			$result_array['indicators'] = (array)$p_result->getIndicators();
+			ApiResult::setArrayType( $result_array['indicators'], 'BCkvp', 'name' );
 		}
 
 		if ( isset( $prop['iwlinks'] ) ) {
@@ -378,15 +362,16 @@ class ApiParse extends ApiBase {
 		}
 
 		if ( isset( $prop['wikitext'] ) ) {
-			$result_array['wikitext'] = array();
-			ApiResult::setContentValue( $result_array['wikitext'], 'wikitext', $this->content->serialize( $format ) );
+			$result_array['wikitext'] = $this->content->serialize( $format );
+			$result_array[ApiResult::META_BC_SUBELEMENTS][] = 'wikitext';
 			if ( !is_null( $this->pstContent ) ) {
-				$result_array['psttext'] = array();
-				ApiResult::setContentValue( $result_array['psttext'], 'psttext', $this->pstContent->serialize( $format ) );
+				$result_array['psttext'] = $this->pstContent->serialize( $format );
+				$result_array[ApiResult::META_BC_SUBELEMENTS][] = 'psttext';
 			}
 		}
 		if ( isset( $prop['properties'] ) ) {
-			$result_array['properties'] = $this->formatProperties( $p_result->getProperties() );
+			$result_array['properties'] = (array)$p_result->getProperties();
+			ApiResult::setArrayType( $result_array['properties'], 'BCkvp', 'name' );
 		}
 
 		if ( isset( $prop['limitreportdata'] ) ) {
@@ -394,9 +379,8 @@ class ApiParse extends ApiBase {
 				$this->formatLimitReportData( $p_result->getLimitReportData() );
 		}
 		if ( isset( $prop['limitreporthtml'] ) ) {
-			$limitreportHtml = EditPage::getPreviewLimitReport( $p_result );
-			$result_array['limitreporthtml'] = array();
-			ApiResult::setContentValue( $result_array['limitreporthtml'], 'limitreporthtml', $limitreportHtml );
+			$result_array['limitreporthtml'] = EditPage::getPreviewLimitReport( $p_result );
+			$result_array[ApiResult::META_BC_SUBELEMENTS][] = 'limitreporthtml';
 		}
 
 		if ( $params['generatexml'] ) {
@@ -411,8 +395,8 @@ class ApiParse extends ApiBase {
 			} else {
 				$xml = $dom->__toString();
 			}
-			$result_array['parsetree'] = array();
-			ApiResult::setContentValue( $result_array['parsetree'], 'parsetree', $xml );
+			$result_array['parsetree'] = $xml;
+			$result_array[ApiResult::META_BC_SUBELEMENTS][] = 'parsetree';
 		}
 
 		$result_mapping = array(
@@ -589,9 +573,9 @@ class ApiParse extends ApiBase {
 			$entry['sortkey'] = $sortkey;
 			ApiResult::setContentValue( $entry, 'category', $link );
 			if ( !isset( $hiddencats[$link] ) ) {
-				$entry['missing'] = '';
+				$entry['missing'] = true;
 			} elseif ( $hiddencats[$link] ) {
-				$entry['hidden'] = '';
+				$entry['hidden'] = true;
 			}
 			$result[] = $entry;
 		}
@@ -613,9 +597,7 @@ class ApiParse extends ApiBase {
 				$entry = array();
 				$entry['ns'] = $ns;
 				ApiResult::setContentValue( $entry, 'title', Title::makeTitle( $ns, $title )->getFullText() );
-				if ( $id != 0 ) {
-					$entry['exists'] = '';
-				}
+				$entry['exists'] = $id != 0;
 				$result[] = $entry;
 			}
 		}
@@ -655,18 +637,6 @@ class ApiParse extends ApiBase {
 		return $result;
 	}
 
-	private function formatProperties( $properties ) {
-		$result = array();
-		foreach ( $properties as $name => $value ) {
-			$entry = array();
-			$entry['name'] = $name;
-			ApiResult::setContentValue( $entry, 'value', $value );
-			$result[] = $entry;
-		}
-
-		return $result;
-	}
-
 	private function formatCss( $css ) {
 		$result = array();
 		foreach ( $css as $file => $link ) {
@@ -689,8 +659,7 @@ class ApiParse extends ApiBase {
 			if ( !is_array( $value ) ) {
 				$value = array( $value );
 			}
-			ApiResult::setIndexedTagName( $value, 'param' );
-			ApiResult::setIndexedTagNameOnSubarrays( $value, 'param' );
+			ApiResult::setIndexedTagNameRecursive( $value, 'param' );
 			$entry = array_merge( $entry, $value );
 			$result[] = $entry;
 		}
diff --git a/includes/api/ApiProtect.php b/includes/api/ApiProtect.php
index 496db8fec7..c07aaca436 100644
--- a/includes/api/ApiProtect.php
+++ b/includes/api/ApiProtect.php
@@ -123,7 +123,7 @@ class ApiProtect extends ApiBase {
 			'reason' => $params['reason']
 		);
 		if ( $cascade ) {
-			$res['cascade'] = '';
+			$res['cascade'] = true;
 		}
 		$res['protections'] = $resultProtections;
 		$result = $this->getResult();
diff --git a/includes/api/ApiPurge.php b/includes/api/ApiPurge.php
index 67f78349f4..a22be498c5 100644
--- a/includes/api/ApiPurge.php
+++ b/includes/api/ApiPurge.php
@@ -53,7 +53,7 @@ class ApiPurge extends ApiBase {
 			ApiQueryBase::addTitleInfo( $r, $title );
 			$page = WikiPage::factory( $title );
 			$page->doPurge(); // Directly purge and skip the UI part of purge().
-			$r['purged'] = '';
+			$r['purged'] = true;
 
 			if ( $forceLinkUpdate || $forceRecursiveLinkUpdate ) {
 				if ( !$this->getUser()->pingLimiter( 'linkpurge' ) ) {
@@ -74,7 +74,7 @@ class ApiPurge extends ApiBase {
 						$title, null, $forceRecursiveLinkUpdate, $p_result );
 					DataUpdate::runUpdates( $updates );
 
-					$r['linkupdate'] = '';
+					$r['linkupdate'] = true;
 
 					if ( $enableParserCache ) {
 						$pcache = ParserCache::singleton();
diff --git a/includes/api/ApiQuery.php b/includes/api/ApiQuery.php
index b1069c736b..082fccb670 100644
--- a/includes/api/ApiQuery.php
+++ b/includes/api/ApiQuery.php
@@ -403,18 +403,18 @@ class ApiQuery extends ApiBase {
 		foreach ( $pageSet->getMissingTitles() as $fakeId => $title ) {
 			$vals = array();
 			ApiQueryBase::addTitleInfo( $vals, $title );
-			$vals['missing'] = '';
+			$vals['missing'] = true;
 			$pages[$fakeId] = $vals;
 		}
 		// Report any invalid titles
 		foreach ( $pageSet->getInvalidTitles() as $fakeId => $title ) {
-			$pages[$fakeId] = array( 'title' => $title, 'invalid' => '' );
+			$pages[$fakeId] = array( 'title' => $title, 'invalid' => true );
 		}
 		// Report any missing page ids
 		foreach ( $pageSet->getMissingPageIDs() as $pageid ) {
 			$pages[$pageid] = array(
 				'pageid' => $pageid,
-				'missing' => ''
+				'missing' => true
 			);
 		}
 		// Report special pages
@@ -422,15 +422,15 @@ class ApiQuery extends ApiBase {
 		foreach ( $pageSet->getSpecialTitles() as $fakeId => $title ) {
 			$vals = array();
 			ApiQueryBase::addTitleInfo( $vals, $title );
-			$vals['special'] = '';
+			$vals['special'] = true;
 			if ( $title->isSpecialPage() &&
 				!SpecialPageFactory::exists( $title->getDBkey() )
 			) {
-				$vals['missing'] = '';
+				$vals['missing'] = true;
 			} elseif ( $title->getNamespace() == NS_MEDIA &&
 				!wfFindFile( $title )
 			) {
-				$vals['missing'] = '';
+				$vals['missing'] = true;
 			}
 			$pages[$fakeId] = $vals;
 		}
@@ -445,6 +445,7 @@ class ApiQuery extends ApiBase {
 
 		if ( count( $pages ) ) {
 			$pageSet->populateGeneratorData( $pages );
+			ApiResult::setArrayType( $pages, 'BCarray' );
 
 			if ( $this->mParams['indexpageids'] ) {
 				$pageIDs = array_keys( $pages );
@@ -525,9 +526,8 @@ class ApiQuery extends ApiBase {
 			$result->addValue( null, 'text', $exportxml, ApiResult::NO_SIZE_CHECK );
 			$result->addValue( null, 'mime', 'text/xml', ApiResult::NO_SIZE_CHECK );
 		} else {
-			$r = array();
-			ApiResult::setContentValue( $r, 'xml', $exportxml );
-			$result->addValue( 'query', 'export', $r, ApiResult::NO_SIZE_CHECK );
+			$result->addValue( 'query', 'export', $exportxml, ApiResult::NO_SIZE_CHECK );
+			$result->addValue( 'query', ApiResult::META_BC_SUBELEMENTS, array( 'export' ) );
 		}
 	}
 
diff --git a/includes/api/ApiQueryAllCategories.php b/includes/api/ApiQueryAllCategories.php
index 4ecc4b7af5..cc0b71afbc 100644
--- a/includes/api/ApiQueryAllCategories.php
+++ b/includes/api/ApiQueryAllCategories.php
@@ -135,8 +135,8 @@ class ApiQueryAllCategories extends ApiQueryGeneratorBase {
 					$item['files'] = intval( $row->cat_files );
 					$item['subcats'] = intval( $row->cat_subcats );
 				}
-				if ( isset( $prop['hidden'] ) && $row->cat_hidden ) {
-					$item['hidden'] = '';
+				if ( isset( $prop['hidden'] ) ) {
+					$item['hidden'] = (bool)$row->cat_hidden;
 				}
 				$fit = $result->addValue( array( 'query', $this->getModuleName() ), null, $item );
 				if ( !$fit ) {
diff --git a/includes/api/ApiQueryAllLinks.php b/includes/api/ApiQueryAllLinks.php
index 1a4a4d9041..fadecfb47e 100644
--- a/includes/api/ApiQueryAllLinks.php
+++ b/includes/api/ApiQueryAllLinks.php
@@ -200,7 +200,9 @@ class ApiQueryAllLinks extends ApiQueryGeneratorBase {
 			}
 
 			if ( is_null( $resultPageSet ) ) {
-				$vals = array();
+				$vals = array(
+					ApiResult::META_TYPE => 'assoc',
+				);
 				if ( $fld_ids ) {
 					$vals['fromid'] = intval( $row->pl_from );
 				}
diff --git a/includes/api/ApiQueryAllMessages.php b/includes/api/ApiQueryAllMessages.php
index 00816a3268..44af83d03e 100644
--- a/includes/api/ApiQueryAllMessages.php
+++ b/includes/api/ApiQueryAllMessages.php
@@ -146,7 +146,7 @@ class ApiQueryAllMessages extends ApiQueryBase {
 					$messageIsCustomised = isset( $customisedMessages['pages'][$langObj->ucfirst( $message )] );
 					if ( $customised === $messageIsCustomised ) {
 						if ( $customised ) {
-							$a['customised'] = '';
+							$a['customised'] = true;
 						}
 					} else {
 						continue;
@@ -156,7 +156,7 @@ class ApiQueryAllMessages extends ApiQueryBase {
 				$msg = wfMessage( $message, $args )->inLanguage( $langObj );
 
 				if ( !$msg->exists() ) {
-					$a['missing'] = '';
+					$a['missing'] = true;
 				} else {
 					// Check if the parser is enabled:
 					if ( $params['enableparser'] ) {
@@ -170,7 +170,7 @@ class ApiQueryAllMessages extends ApiQueryBase {
 					if ( isset( $prop['default'] ) ) {
 						$default = wfMessage( $message )->inLanguage( $langObj )->useDatabase( false );
 						if ( !$default->exists() ) {
-							$a['defaultmissing'] = '';
+							$a['defaultmissing'] = true;
 						} elseif ( $default->plain() != $msgString ) {
 							$a['default'] = $default->plain();
 						}
diff --git a/includes/api/ApiQueryAllUsers.php b/includes/api/ApiQueryAllUsers.php
index 8c9e1baa81..d7354e2660 100644
--- a/includes/api/ApiQueryAllUsers.php
+++ b/includes/api/ApiQueryAllUsers.php
@@ -253,7 +253,7 @@ class ApiQueryAllUsers extends ApiQueryBase {
 				$data['blockexpiry'] = $row->ipb_expiry;
 			}
 			if ( $row->ipb_deleted ) {
-				$data['hidden'] = '';
+				$data['hidden'] = true;
 			}
 			if ( $fld_editcount ) {
 				$data['editcount'] = intval( $row->user_editcount );
diff --git a/includes/api/ApiQueryBacklinks.php b/includes/api/ApiQueryBacklinks.php
index 92cf62df86..1df14e0b8a 100644
--- a/includes/api/ApiQueryBacklinks.php
+++ b/includes/api/ApiQueryBacklinks.php
@@ -194,7 +194,7 @@ class ApiQueryBacklinks extends ApiQueryGeneratorBase {
 				$a = array( 'pageid' => intval( $row->page_id ) );
 				ApiQueryBase::addTitleInfo( $a, $t );
 				if ( $row->page_is_redirect ) {
-					$a['redirect'] = '';
+					$a['redirect'] = true;
 				}
 				// Put all the results in an array first
 				$this->resultArr[$a['pageid']] = $a;
@@ -313,7 +313,7 @@ class ApiQueryBacklinks extends ApiQueryGeneratorBase {
 				$a['pageid'] = intval( $row->page_id );
 				ApiQueryBase::addTitleInfo( $a, Title::makeTitle( $row->page_namespace, $row->page_title ) );
 				if ( $row->page_is_redirect ) {
-					$a['redirect'] = '';
+					$a['redirect'] = true;
 				}
 				$parentID = $this->pageMap[$ns][$row->{$this->bl_title}];
 				// Put all the results in an array first
diff --git a/includes/api/ApiQueryBacklinksprop.php b/includes/api/ApiQueryBacklinksprop.php
index b4752ae9d4..8e271e7b9a 100644
--- a/includes/api/ApiQueryBacklinksprop.php
+++ b/includes/api/ApiQueryBacklinksprop.php
@@ -287,8 +287,8 @@ class ApiQueryBacklinksprop extends ApiQueryGeneratorBase {
 				if ( $fld_fragment && $row->rd_fragment !== null && $row->rd_fragment !== '' ) {
 					$vals['fragment'] = $row->rd_fragment;
 				}
-				if ( $fld_redirect && $row->page_is_redirect ) {
-					$vals['redirect'] = '';
+				if ( $fld_redirect ) {
+					$vals['redirect'] = (bool)$row->page_is_redirect;
 				}
 				$fit = $this->addPageSubItem( $id, $vals );
 				if ( !$fit ) {
diff --git a/includes/api/ApiQueryBlocks.php b/includes/api/ApiQueryBlocks.php
index 72e4fefb85..4a7023b763 100644
--- a/includes/api/ApiQueryBlocks.php
+++ b/includes/api/ApiQueryBlocks.php
@@ -187,7 +187,9 @@ class ApiQueryBlocks extends ApiQueryBase {
 				$this->setContinueEnumParameter( 'continue', "$row->ipb_timestamp|$row->ipb_id" );
 				break;
 			}
-			$block = array();
+			$block = array(
+				ApiResult::META_TYPE => 'assoc',
+			);
 			if ( $fld_id ) {
 				$block['id'] = $row->ipb_id;
 			}
@@ -218,27 +220,13 @@ class ApiQueryBlocks extends ApiQueryBase {
 			}
 			if ( $fld_flags ) {
 				// For clarity, these flags use the same names as their action=block counterparts
-				if ( $row->ipb_auto ) {
-					$block['automatic'] = '';
-				}
-				if ( $row->ipb_anon_only ) {
-					$block['anononly'] = '';
-				}
-				if ( $row->ipb_create_account ) {
-					$block['nocreate'] = '';
-				}
-				if ( $row->ipb_enable_autoblock ) {
-					$block['autoblock'] = '';
-				}
-				if ( $row->ipb_block_email ) {
-					$block['noemail'] = '';
-				}
-				if ( $row->ipb_deleted ) {
-					$block['hidden'] = '';
-				}
-				if ( $row->ipb_allow_usertalk ) {
-					$block['allowusertalk'] = '';
-				}
+				$block['automatic'] = (bool)$row->ipb_auto;
+				$block['anononly'] = (bool)$row->ipb_anon_only;
+				$block['nocreate'] = (bool)$row->ipb_create_account;
+				$block['autoblock'] = (bool)$row->ipb_enable_autoblock;
+				$block['noemail'] = (bool)$row->ipb_block_email;
+				$block['hidden'] = (bool)$row->ipb_deleted;
+				$block['allowusertalk'] = (bool)$row->ipb_allow_usertalk;
 			}
 			$fit = $result->addValue( array( 'query', $this->getModuleName() ), null, $block );
 			if ( !$fit ) {
diff --git a/includes/api/ApiQueryCategories.php b/includes/api/ApiQueryCategories.php
index 6aa714e747..35fa56efd1 100644
--- a/includes/api/ApiQueryCategories.php
+++ b/includes/api/ApiQueryCategories.php
@@ -150,8 +150,8 @@ class ApiQueryCategories extends ApiQueryGeneratorBase {
 				if ( isset( $prop['timestamp'] ) ) {
 					$vals['timestamp'] = wfTimestamp( TS_ISO_8601, $row->cl_timestamp );
 				}
-				if ( isset( $prop['hidden'] ) && !is_null( $row->pp_propname ) ) {
-					$vals['hidden'] = '';
+				if ( isset( $prop['hidden'] ) ) {
+					$vals['hidden'] = !is_null( $row->pp_propname );
 				}
 
 				$fit = $this->addPageSubItem( $row->cl_from, $vals );
diff --git a/includes/api/ApiQueryCategoryInfo.php b/includes/api/ApiQueryCategoryInfo.php
index 5c67ebf279..9f6c604496 100644
--- a/includes/api/ApiQueryCategoryInfo.php
+++ b/includes/api/ApiQueryCategoryInfo.php
@@ -86,9 +86,7 @@ class ApiQueryCategoryInfo extends ApiQueryBase {
 			$vals['pages'] = $row->cat_pages - $row->cat_subcats - $row->cat_files;
 			$vals['files'] = intval( $row->cat_files );
 			$vals['subcats'] = intval( $row->cat_subcats );
-			if ( $row->cat_hidden ) {
-				$vals['hidden'] = '';
-			}
+			$vals['hidden'] = (bool)$row->cat_hidden;
 			$fit = $this->addPageSubItems( $catids[$row->cat_title], $vals );
 			if ( !$fit ) {
 				$this->setContinueEnumParameter( 'continue', $row->cat_title );
diff --git a/includes/api/ApiQueryCategoryMembers.php b/includes/api/ApiQueryCategoryMembers.php
index 82ab939832..ec0c1d146b 100644
--- a/includes/api/ApiQueryCategoryMembers.php
+++ b/includes/api/ApiQueryCategoryMembers.php
@@ -246,7 +246,9 @@ class ApiQueryCategoryMembers extends ApiQueryGeneratorBase {
 			}
 
 			if ( is_null( $resultPageSet ) ) {
-				$vals = array();
+				$vals = array(
+					ApiResult::META_TYPE => 'assoc',
+				);
 				if ( $fld_ids ) {
 					$vals['pageid'] = intval( $row->page_id );
 				}
diff --git a/includes/api/ApiQueryDeletedrevs.php b/includes/api/ApiQueryDeletedrevs.php
index b2c59d8d22..72a331f1cc 100644
--- a/includes/api/ApiQueryDeletedrevs.php
+++ b/includes/api/ApiQueryDeletedrevs.php
@@ -320,7 +320,7 @@ class ApiQueryDeletedrevs extends ApiQueryBase {
 			}
 			if ( $fld_user || $fld_userid ) {
 				if ( $row->ar_deleted & Revision::DELETED_USER ) {
-					$rev['userhidden'] = '';
+					$rev['userhidden'] = true;
 					$anyHidden = true;
 				}
 				if ( Revision::userCanBitfield( $row->ar_deleted, Revision::DELETED_USER, $user ) ) {
@@ -335,7 +335,7 @@ class ApiQueryDeletedrevs extends ApiQueryBase {
 
 			if ( $fld_comment || $fld_parsedcomment ) {
 				if ( $row->ar_deleted & Revision::DELETED_COMMENT ) {
-					$rev['commenthidden'] = '';
+					$rev['commenthidden'] = true;
 					$anyHidden = true;
 				}
 				if ( Revision::userCanBitfield( $row->ar_deleted, Revision::DELETED_COMMENT, $user ) ) {
@@ -349,15 +349,15 @@ class ApiQueryDeletedrevs extends ApiQueryBase {
 				}
 			}
 
-			if ( $fld_minor && $row->ar_minor_edit == 1 ) {
-				$rev['minor'] = '';
+			if ( $fld_minor ) {
+				$rev['minor'] = $row->ar_minor_edit == 1;
 			}
 			if ( $fld_len ) {
 				$rev['len'] = $row->ar_len;
 			}
 			if ( $fld_sha1 ) {
 				if ( $row->ar_deleted & Revision::DELETED_TEXT ) {
-					$rev['sha1hidden'] = '';
+					$rev['sha1hidden'] = true;
 					$anyHidden = true;
 				}
 				if ( Revision::userCanBitfield( $row->ar_deleted, Revision::DELETED_TEXT, $user ) ) {
@@ -370,7 +370,7 @@ class ApiQueryDeletedrevs extends ApiQueryBase {
 			}
 			if ( $fld_content ) {
 				if ( $row->ar_deleted & Revision::DELETED_TEXT ) {
-					$rev['texthidden'] = '';
+					$rev['texthidden'] = true;
 					$anyHidden = true;
 				}
 				if ( Revision::userCanBitfield( $row->ar_deleted, Revision::DELETED_TEXT, $user ) ) {
@@ -394,7 +394,7 @@ class ApiQueryDeletedrevs extends ApiQueryBase {
 			}
 
 			if ( $anyHidden && ( $row->ar_deleted & Revision::DELETED_RESTRICTED ) ) {
-				$rev['suppressed'] = '';
+				$rev['suppressed'] = true;
 			}
 
 			if ( !isset( $pageMap[$row->ar_namespace][$row->ar_title] ) ) {
diff --git a/includes/api/ApiQueryDuplicateFiles.php b/includes/api/ApiQueryDuplicateFiles.php
index 010f8d59a7..4d0bcfed31 100644
--- a/includes/api/ApiQueryDuplicateFiles.php
+++ b/includes/api/ApiQueryDuplicateFiles.php
@@ -137,11 +137,9 @@ class ApiQueryDuplicateFiles extends ApiQueryGeneratorBase {
 					$r = array(
 						'name' => $dupName,
 						'user' => $dupFile->getUser( 'text' ),
-						'timestamp' => wfTimestamp( TS_ISO_8601, $dupFile->getTimestamp() )
+						'timestamp' => wfTimestamp( TS_ISO_8601, $dupFile->getTimestamp() ),
+						'shared' => !$dupFile->isLocal(),
 					);
-					if ( !$dupFile->isLocal() ) {
-						$r['shared'] = '';
-					}
 					$fit = $this->addPageSubItem( $pageId, $r );
 					if ( !$fit ) {
 						$this->setContinueEnumParameter( 'continue', $image . '|' . $dupName );
diff --git a/includes/api/ApiQueryExtLinksUsage.php b/includes/api/ApiQueryExtLinksUsage.php
index a26eff273d..3f65a19e8f 100644
--- a/includes/api/ApiQueryExtLinksUsage.php
+++ b/includes/api/ApiQueryExtLinksUsage.php
@@ -112,7 +112,9 @@ class ApiQueryExtLinksUsage extends ApiQueryGeneratorBase {
 			}
 
 			if ( is_null( $resultPageSet ) ) {
-				$vals = array();
+				$vals = array(
+					ApiResult::META_TYPE => 'assoc',
+				);
 				if ( $fld_ids ) {
 					$vals['pageid'] = intval( $row->page_id );
 				}
diff --git a/includes/api/ApiQueryFileRepoInfo.php b/includes/api/ApiQueryFileRepoInfo.php
index 88961400ae..9ad7e27e6b 100644
--- a/includes/api/ApiQueryFileRepoInfo.php
+++ b/includes/api/ApiQueryFileRepoInfo.php
@@ -56,6 +56,8 @@ class ApiQueryFileRepoInfo extends ApiQueryBase {
 
 		$result = $this->getResult();
 		ApiResult::setIndexedTagName( $repos, 'repo' );
+		ApiResult::setArrayTypeRecursive( $repos, 'assoc' );
+		ApiResult::setArrayType( $repos, 'array' );
 		$result->addValue( array( 'query' ), 'repos', $repos );
 	}
 
diff --git a/includes/api/ApiQueryFilearchive.php b/includes/api/ApiQueryFilearchive.php
index cba3b7353c..4d357a7f4c 100644
--- a/includes/api/ApiQueryFilearchive.php
+++ b/includes/api/ApiQueryFilearchive.php
@@ -218,17 +218,17 @@ class ApiQueryFilearchive extends ApiQueryBase {
 			}
 
 			if ( $row->fa_deleted & File::DELETED_FILE ) {
-				$file['filehidden'] = '';
+				$file['filehidden'] = true;
 			}
 			if ( $row->fa_deleted & File::DELETED_COMMENT ) {
-				$file['commenthidden'] = '';
+				$file['commenthidden'] = true;
 			}
 			if ( $row->fa_deleted & File::DELETED_USER ) {
-				$file['userhidden'] = '';
+				$file['userhidden'] = true;
 			}
 			if ( $row->fa_deleted & File::DELETED_RESTRICTED ) {
 				// This file is deleted for normal admins
-				$file['suppressed'] = '';
+				$file['suppressed'] = true;
 			}
 
 			$fit = $result->addValue( array( 'query', $this->getModuleName() ), null, $file );
diff --git a/includes/api/ApiQueryIWBacklinks.php b/includes/api/ApiQueryIWBacklinks.php
index 61928c3c42..618387d2b7 100644
--- a/includes/api/ApiQueryIWBacklinks.php
+++ b/includes/api/ApiQueryIWBacklinks.php
@@ -132,7 +132,7 @@ class ApiQueryIWBacklinks extends ApiQueryGeneratorBase {
 				ApiQueryBase::addTitleInfo( $entry, $title );
 
 				if ( $row->page_is_redirect ) {
-					$entry['redirect'] = '';
+					$entry['redirect'] = true;
 				}
 
 				if ( $iwprefix ) {
diff --git a/includes/api/ApiQueryImageInfo.php b/includes/api/ApiQueryImageInfo.php
index d5da4951c3..94b4bbdb48 100644
--- a/includes/api/ApiQueryImageInfo.php
+++ b/includes/api/ApiQueryImageInfo.php
@@ -373,7 +373,9 @@ class ApiQueryImageInfo extends ApiQueryBase {
 			);
 		}
 		$version = $opts['version'];
-		$vals = array();
+		$vals = array(
+			ApiResult::META_TYPE => 'assoc',
+		);
 		// Timestamp is shown even if the file is revdelete'd in interface
 		// so do same here.
 		if ( isset( $prop['timestamp'] ) ) {
@@ -397,7 +399,7 @@ class ApiQueryImageInfo extends ApiQueryBase {
 
 		if ( $user || $userid ) {
 			if ( $file->isDeleted( File::DELETED_USER ) ) {
-				$vals['userhidden'] = '';
+				$vals['userhidden'] = true;
 				$anyHidden = true;
 			}
 			if ( $canShowField( File::DELETED_USER ) ) {
@@ -408,7 +410,7 @@ class ApiQueryImageInfo extends ApiQueryBase {
 					$vals['userid'] = $file->getUser( 'id' );
 				}
 				if ( !$file->getUser( 'id' ) ) {
-					$vals['anon'] = '';
+					$vals['anon'] = true;
 				}
 			}
 		}
@@ -438,7 +440,7 @@ class ApiQueryImageInfo extends ApiQueryBase {
 
 		if ( $pcomment || $comment ) {
 			if ( $file->isDeleted( File::DELETED_COMMENT ) ) {
-				$vals['commenthidden'] = '';
+				$vals['commenthidden'] = true;
 				$anyHidden = true;
 			}
 			if ( $canShowField( File::DELETED_COMMENT ) ) {
@@ -469,7 +471,7 @@ class ApiQueryImageInfo extends ApiQueryBase {
 		}
 
 		if ( $file->isDeleted( File::DELETED_FILE ) ) {
-			$vals['filehidden'] = '';
+			$vals['filehidden'] = true;
 			$anyHidden = true;
 		}
 
diff --git a/includes/api/ApiQueryInfo.php b/includes/api/ApiQueryInfo.php
index db28df7461..66178d4f72 100644
--- a/includes/api/ApiQueryInfo.php
+++ b/includes/api/ApiQueryInfo.php
@@ -395,10 +395,10 @@ class ApiQueryInfo extends ApiQueryBase {
 			$pageInfo['length'] = intval( $this->pageLength[$pageid] );
 
 			if ( isset( $this->pageIsRedir[$pageid] ) && $this->pageIsRedir[$pageid] ) {
-				$pageInfo['redirect'] = '';
+				$pageInfo['redirect'] = true;
 			}
 			if ( $this->pageIsNew[$pageid] ) {
-				$pageInfo['new'] = '';
+				$pageInfo['new'] = true;
 			}
 		}
 
@@ -431,8 +431,8 @@ class ApiQueryInfo extends ApiQueryBase {
 			ApiResult::setIndexedTagName( $pageInfo['restrictiontypes'], 'rt' );
 		}
 
-		if ( $this->fld_watched && isset( $this->watched[$ns][$dbkey] ) ) {
-			$pageInfo['watched'] = '';
+		if ( $this->fld_watched ) {
+			$pageInfo['watched'] = isset( $this->watched[$ns][$dbkey] );
 		}
 
 		if ( $this->fld_watchers ) {
@@ -464,8 +464,8 @@ class ApiQueryInfo extends ApiQueryBase {
 			$pageInfo['editurl'] = wfExpandUrl( $title->getFullURL( 'action=edit' ), PROTO_CURRENT );
 			$pageInfo['canonicalurl'] = wfExpandUrl( $title->getFullURL(), PROTO_CANONICAL );
 		}
-		if ( $this->fld_readable && $title->userCan( 'read', $this->getUser() ) ) {
-			$pageInfo['readable'] = '';
+		if ( $this->fld_readable ) {
+			$pageInfo['readable'] = $title->userCan( 'read', $this->getUser() );
 		}
 
 		if ( $this->fld_preload ) {
@@ -497,9 +497,7 @@ class ApiQueryInfo extends ApiQueryBase {
 			$pageInfo['actions'] = array();
 			foreach ( $this->params['testactions'] as $action ) {
 				$this->countTestedActions++;
-				if ( $title->userCan( $action, $user ) ) {
-					$pageInfo['actions'][$action] = '';
-				}
+				$pageInfo['actions'][$action] = $title->userCan( $action, $user );
 			}
 		}
 
@@ -532,7 +530,7 @@ class ApiQueryInfo extends ApiQueryBase {
 					'expiry' => $wgContLang->formatExpiry( $row->pr_expiry, TS_ISO_8601 )
 				);
 				if ( $row->pr_cascade ) {
-					$a['cascade'] = '';
+					$a['cascade'] = true;
 				}
 				$this->protections[$title->getNamespace()][$title->getDBkey()][] = $a;
 			}
diff --git a/includes/api/ApiQueryLangBacklinks.php b/includes/api/ApiQueryLangBacklinks.php
index 885d10c141..7be18b2ff7 100644
--- a/includes/api/ApiQueryLangBacklinks.php
+++ b/includes/api/ApiQueryLangBacklinks.php
@@ -131,7 +131,7 @@ class ApiQueryLangBacklinks extends ApiQueryGeneratorBase {
 				ApiQueryBase::addTitleInfo( $entry, $title );
 
 				if ( $row->page_is_redirect ) {
-					$entry['redirect'] = '';
+					$entry['redirect'] = true;
 				}
 
 				if ( $lllang ) {
diff --git a/includes/api/ApiQueryLogEvents.php b/includes/api/ApiQueryLogEvents.php
index 553747e548..7b2381f4d3 100644
--- a/includes/api/ApiQueryLogEvents.php
+++ b/includes/api/ApiQueryLogEvents.php
@@ -230,9 +230,6 @@ class ApiQueryLogEvents extends ApiQueryBase {
 			}
 
 			$vals = $this->extractRowInfo( $row );
-			if ( !$vals ) {
-				continue;
-			}
 			$fit = $result->addValue( array( 'query', $this->getModuleName() ), null, $vals );
 			if ( !$fit ) {
 				$this->setContinueEnumParameter( 'continue', "$row->log_timestamp|$row->log_id" );
@@ -270,7 +267,9 @@ class ApiQueryLogEvents extends ApiQueryBase {
 
 	private function extractRowInfo( $row ) {
 		$logEntry = DatabaseLogEntry::newFromRow( $row );
-		$vals = array();
+		$vals = array(
+			ApiResult::META_TYPE => 'assoc',
+		);
 		$anyHidden = false;
 		$user = $this->getUser();
 
@@ -284,7 +283,7 @@ class ApiQueryLogEvents extends ApiQueryBase {
 
 		if ( $this->fld_title || $this->fld_ids || $this->fld_details && $row->log_params !== '' ) {
 			if ( LogEventsList::isDeleted( $row, LogPage::DELETED_ACTION ) ) {
-				$vals['actionhidden'] = '';
+				$vals['actionhidden'] = true;
 				$anyHidden = true;
 			}
 			if ( LogEventsList::userCan( $row, LogPage::DELETED_ACTION, $user ) ) {
@@ -308,7 +307,7 @@ class ApiQueryLogEvents extends ApiQueryBase {
 
 		if ( $this->fld_user || $this->fld_userid ) {
 			if ( LogEventsList::isDeleted( $row, LogPage::DELETED_USER ) ) {
-				$vals['userhidden'] = '';
+				$vals['userhidden'] = true;
 				$anyHidden = true;
 			}
 			if ( LogEventsList::userCan( $row, LogPage::DELETED_USER, $user ) ) {
@@ -320,7 +319,7 @@ class ApiQueryLogEvents extends ApiQueryBase {
 				}
 
 				if ( !$row->log_user ) {
-					$vals['anon'] = '';
+					$vals['anon'] = true;
 				}
 			}
 		}
@@ -330,7 +329,7 @@ class ApiQueryLogEvents extends ApiQueryBase {
 
 		if ( ( $this->fld_comment || $this->fld_parsedcomment ) && isset( $row->log_comment ) ) {
 			if ( LogEventsList::isDeleted( $row, LogPage::DELETED_COMMENT ) ) {
-				$vals['commenthidden'] = '';
+				$vals['commenthidden'] = true;
 				$anyHidden = true;
 			}
 			if ( LogEventsList::userCan( $row, LogPage::DELETED_COMMENT, $user ) ) {
@@ -355,7 +354,7 @@ class ApiQueryLogEvents extends ApiQueryBase {
 		}
 
 		if ( $anyHidden && LogEventsList::isDeleted( $row, LogPage::DELETED_RESTRICTED ) ) {
-			$vals['suppressed'] = '';
+			$vals['suppressed'] = true;
 		}
 
 		return $vals;
diff --git a/includes/api/ApiQueryPageProps.php b/includes/api/ApiQueryPageProps.php
index 269afb147c..dd19bf23cf 100644
--- a/includes/api/ApiQueryPageProps.php
+++ b/includes/api/ApiQueryPageProps.php
@@ -110,6 +110,7 @@ class ApiQueryPageProps extends ApiQueryBase {
 	 * @return bool True if it fits in the result
 	 */
 	private function addPageProps( $result, $page, $props ) {
+		ApiResult::setArrayType( $props, 'assoc' );
 		$fit = $result->addValue( array( 'query', 'pages', $page ), 'pageprops', $props );
 
 		if ( !$fit ) {
diff --git a/includes/api/ApiQueryPagesWithProp.php b/includes/api/ApiQueryPagesWithProp.php
index 143bc06d86..7bcaf24722 100644
--- a/includes/api/ApiQueryPagesWithProp.php
+++ b/includes/api/ApiQueryPagesWithProp.php
@@ -99,7 +99,9 @@ class ApiQueryPagesWithProp extends ApiQueryGeneratorBase {
 			}
 
 			if ( $resultPageSet === null ) {
-				$vals = array();
+				$vals = array(
+					ApiResult::META_TYPE => 'assoc',
+				);
 				if ( $fld_ids ) {
 					$vals['pageid'] = (int)$row->page_id;
 				}
diff --git a/includes/api/ApiQueryPrefixSearch.php b/includes/api/ApiQueryPrefixSearch.php
index 35942ca6a5..8eb644fcf9 100644
--- a/includes/api/ApiQueryPrefixSearch.php
+++ b/includes/api/ApiQueryPrefixSearch.php
@@ -69,7 +69,7 @@ class ApiQueryPrefixSearch extends ApiQueryGeneratorBase {
 					'title' => $title->getPrefixedText(),
 				);
 				if ( $title->isSpecialPage() ) {
-					$vals['special'] = '';
+					$vals['special'] = true;
 				} else {
 					$vals['pageid'] = intval( $title->getArticleId() );
 				}
diff --git a/includes/api/ApiQueryQueryPage.php b/includes/api/ApiQueryQueryPage.php
index 062a44f8e4..650ac8fef9 100644
--- a/includes/api/ApiQueryQueryPage.php
+++ b/includes/api/ApiQueryQueryPage.php
@@ -68,9 +68,9 @@ class ApiQueryQueryPage extends ApiQueryGeneratorBase {
 		$r = array( 'name' => $params['page'] );
 		if ( $qp->isCached() ) {
 			if ( !$qp->isCacheable() ) {
-				$r['disabled'] = '';
+				$r['disabled'] = true;
 			} else {
-				$r['cached'] = '';
+				$r['cached'] = true;
 				$ts = $qp->getCachedTimestamp();
 				if ( $ts ) {
 					$r['cachedtimestamp'] = wfTimestamp( TS_ISO_8601, $ts );
diff --git a/includes/api/ApiQueryRecentChanges.php b/includes/api/ApiQueryRecentChanges.php
index 28f8b7d9af..f6a64785c4 100644
--- a/includes/api/ApiQueryRecentChanges.php
+++ b/includes/api/ApiQueryRecentChanges.php
@@ -384,9 +384,6 @@ class ApiQueryRecentChanges extends ApiQueryGeneratorBase {
 				$vals = $this->extractRowInfo( $row );
 
 				/* Add that row's data to our final output. */
-				if ( !$vals ) {
-					continue;
-				}
 				$fit = $result->addValue( array( 'query', $this->getModuleName() ), null, $vals );
 				if ( !$fit ) {
 					$this->setContinueEnumParameter( 'continue', "$row->rc_timestamp|$row->rc_id" );
@@ -428,7 +425,7 @@ class ApiQueryRecentChanges extends ApiQueryGeneratorBase {
 		/* Create a new entry in the result for the title. */
 		if ( $this->fld_title || $this->fld_ids ) {
 			if ( $type === RC_LOG && ( $row->rc_deleted & LogPage::DELETED_ACTION ) ) {
-				$vals['actionhidden'] = '';
+				$vals['actionhidden'] = true;
 				$anyHidden = true;
 			}
 			if ( $type !== RC_LOG ||
@@ -452,7 +449,7 @@ class ApiQueryRecentChanges extends ApiQueryGeneratorBase {
 		/* Add user data and 'anon' flag, if user is anonymous. */
 		if ( $this->fld_user || $this->fld_userid ) {
 			if ( $row->rc_deleted & Revision::DELETED_USER ) {
-				$vals['userhidden'] = '';
+				$vals['userhidden'] = true;
 				$anyHidden = true;
 			}
 			if ( Revision::userCanBitfield( $row->rc_deleted, Revision::DELETED_USER, $user ) ) {
@@ -465,22 +462,16 @@ class ApiQueryRecentChanges extends ApiQueryGeneratorBase {
 				}
 
 				if ( !$row->rc_user ) {
-					$vals['anon'] = '';
+					$vals['anon'] = true;
 				}
 			}
 		}
 
 		/* Add flags, such as new, minor, bot. */
 		if ( $this->fld_flags ) {
-			if ( $row->rc_bot ) {
-				$vals['bot'] = '';
-			}
-			if ( $row->rc_type == RC_NEW ) {
-				$vals['new'] = '';
-			}
-			if ( $row->rc_minor ) {
-				$vals['minor'] = '';
-			}
+			$vals['bot'] = (bool)$row->rc_bot;
+			$vals['new'] = $row->rc_type == RC_NEW;
+			$vals['minor'] = (bool)$row->rc_minor;
 		}
 
 		/* Add sizes of each revision. (Only available on 1.10+) */
@@ -497,7 +488,7 @@ class ApiQueryRecentChanges extends ApiQueryGeneratorBase {
 		/* Add edit summary / log summary. */
 		if ( $this->fld_comment || $this->fld_parsedcomment ) {
 			if ( $row->rc_deleted & Revision::DELETED_COMMENT ) {
-				$vals['commenthidden'] = '';
+				$vals['commenthidden'] = true;
 				$anyHidden = true;
 			}
 			if ( Revision::userCanBitfield( $row->rc_deleted, Revision::DELETED_COMMENT, $user ) ) {
@@ -512,23 +503,18 @@ class ApiQueryRecentChanges extends ApiQueryGeneratorBase {
 		}
 
 		if ( $this->fld_redirect ) {
-			if ( $row->page_is_redirect ) {
-				$vals['redirect'] = '';
-			}
+			$vals['redirect'] = (bool)$row->page_is_redirect;
 		}
 
 		/* Add the patrolled flag */
-		if ( $this->fld_patrolled && $row->rc_patrolled == 1 ) {
-			$vals['patrolled'] = '';
-		}
-
-		if ( $this->fld_patrolled && ChangesList::isUnpatrolled( $row, $user ) ) {
-			$vals['unpatrolled'] = '';
+		if ( $this->fld_patrolled ) {
+			$vals['patrolled'] = $row->rc_patrolled == 1;
+			$vals['unpatrolled'] = ChangesList::isUnpatrolled( $row, $user );
 		}
 
 		if ( $this->fld_loginfo && $row->rc_type == RC_LOG ) {
 			if ( $row->rc_deleted & LogPage::DELETED_ACTION ) {
-				$vals['actionhidden'] = '';
+				$vals['actionhidden'] = true;
 				$anyHidden = true;
 			}
 			if ( LogEventsList::userCanBitfield( $row->rc_deleted, LogPage::DELETED_ACTION, $user ) ) {
@@ -551,7 +537,7 @@ class ApiQueryRecentChanges extends ApiQueryGeneratorBase {
 
 		if ( $this->fld_sha1 && $row->rev_sha1 !== null ) {
 			if ( $row->rev_deleted & Revision::DELETED_TEXT ) {
-				$vals['sha1hidden'] = '';
+				$vals['sha1hidden'] = true;
 				$anyHidden = true;
 			}
 			if ( Revision::userCanBitfield( $row->rev_deleted, Revision::DELETED_TEXT, $user ) ) {
@@ -577,7 +563,7 @@ class ApiQueryRecentChanges extends ApiQueryGeneratorBase {
 		}
 
 		if ( $anyHidden && ( $row->rc_deleted & Revision::DELETED_RESTRICTED ) ) {
-			$vals['suppressed'] = '';
+			$vals['suppressed'] = true;
 		}
 
 		return $vals;
diff --git a/includes/api/ApiQueryRevisionsBase.php b/includes/api/ApiQueryRevisionsBase.php
index 1805f40a22..64f6120ae4 100644
--- a/includes/api/ApiQueryRevisionsBase.php
+++ b/includes/api/ApiQueryRevisionsBase.php
@@ -168,13 +168,13 @@ abstract class ApiQueryRevisionsBase extends ApiQueryGeneratorBase {
 			}
 		}
 
-		if ( $this->fld_flags && $revision->isMinor() ) {
-			$vals['minor'] = '';
+		if ( $this->fld_flags ) {
+			$vals['minor'] = $revision->isMinor();
 		}
 
 		if ( $this->fld_user || $this->fld_userid ) {
 			if ( $revision->isDeleted( Revision::DELETED_USER ) ) {
-				$vals['userhidden'] = '';
+				$vals['userhidden'] = true;
 				$anyHidden = true;
 			}
 			if ( $revision->userCan( Revision::DELETED_USER, $user ) ) {
@@ -183,7 +183,7 @@ abstract class ApiQueryRevisionsBase extends ApiQueryGeneratorBase {
 				}
 				$userid = $revision->getUser( Revision::RAW );
 				if ( !$userid ) {
-					$vals['anon'] = '';
+					$vals['anon'] = true;
 				}
 
 				if ( $this->fld_userid ) {
@@ -206,7 +206,7 @@ abstract class ApiQueryRevisionsBase extends ApiQueryGeneratorBase {
 
 		if ( $this->fld_sha1 ) {
 			if ( $revision->isDeleted( Revision::DELETED_TEXT ) ) {
-				$vals['sha1hidden'] = '';
+				$vals['sha1hidden'] = true;
 				$anyHidden = true;
 			}
 			if ( $revision->userCan( Revision::DELETED_TEXT, $user ) ) {
@@ -224,7 +224,7 @@ abstract class ApiQueryRevisionsBase extends ApiQueryGeneratorBase {
 
 		if ( $this->fld_comment || $this->fld_parsedcomment ) {
 			if ( $revision->isDeleted( Revision::DELETED_COMMENT ) ) {
-				$vals['commenthidden'] = '';
+				$vals['commenthidden'] = true;
 				$anyHidden = true;
 			}
 			if ( $revision->userCan( Revision::DELETED_COMMENT, $user ) ) {
@@ -267,10 +267,10 @@ abstract class ApiQueryRevisionsBase extends ApiQueryGeneratorBase {
 				}
 			}
 			if ( $revision->isDeleted( Revision::DELETED_TEXT ) ) {
-				$vals['texthidden'] = '';
+				$vals['texthidden'] = true;
 				$anyHidden = true;
 			} elseif ( !$content ) {
-				$vals['textmissing'] = '';
+				$vals['textmissing'] = true;
 			}
 		}
 		if ( $this->fld_content && $content ) {
@@ -293,7 +293,7 @@ abstract class ApiQueryRevisionsBase extends ApiQueryGeneratorBase {
 					}
 					$vals['parsetree'] = $xml;
 				} else {
-					$vals['badcontentformatforparsetree'] = '';
+					$vals['badcontentformatforparsetree'] = true;
 					$this->setWarning( "Conversion to XML is supported for wikitext only, " .
 						$title->getPrefixedDBkey() .
 						" uses content model " . $content->getModel() );
@@ -314,7 +314,7 @@ abstract class ApiQueryRevisionsBase extends ApiQueryGeneratorBase {
 					$this->setWarning( "Template expansion is supported for wikitext only, " .
 						$title->getPrefixedDBkey() .
 						" uses content model " . $content->getModel() );
-					$vals['badcontentformat'] = '';
+					$vals['badcontentformat'] = true;
 					$text = false;
 				}
 			}
@@ -335,7 +335,7 @@ abstract class ApiQueryRevisionsBase extends ApiQueryGeneratorBase {
 					$name = $title->getPrefixedDBkey();
 					$this->setWarning( "The requested format {$this->contentFormat} is not " .
 						"supported for content model $model used by $name" );
-					$vals['badcontentformat'] = '';
+					$vals['badcontentformat'] = true;
 					$text = false;
 				} else {
 					$text = $content->serialize( $format );
@@ -369,7 +369,7 @@ abstract class ApiQueryRevisionsBase extends ApiQueryGeneratorBase {
 						$name = $title->getPrefixedDBkey();
 						$this->setWarning( "The requested format {$this->contentFormat} is not " .
 							"supported for content model $model used by $name" );
-						$vals['diff']['badcontentformat'] = '';
+						$vals['diff']['badcontentformat'] = true;
 						$engine = null;
 					} else {
 						$difftocontent = ContentHandler::makeContent(
@@ -395,12 +395,12 @@ abstract class ApiQueryRevisionsBase extends ApiQueryGeneratorBase {
 					}
 				}
 			} else {
-				$vals['diff']['notcached'] = '';
+				$vals['diff']['notcached'] = true;
 			}
 		}
 
 		if ( $anyHidden && $revision->isDeleted( Revision::DELETED_RESTRICTED ) ) {
-			$vals['suppressed'] = '';
+			$vals['suppressed'] = true;
 		}
 
 		return $vals;
diff --git a/includes/api/ApiQuerySiteinfo.php b/includes/api/ApiQuerySiteinfo.php
index 22447f74d2..b81e993b66 100644
--- a/includes/api/ApiQuerySiteinfo.php
+++ b/includes/api/ApiQuerySiteinfo.php
@@ -150,9 +150,7 @@ class ApiQuerySiteinfo extends ApiQueryBase {
 		$allowFrom = array( '' );
 		$allowException = true;
 		if ( !$config->get( 'AllowExternalImages' ) ) {
-			if ( $config->get( 'EnableImageWhitelist' ) ) {
-				$data['imagewhitelistenabled'] = '';
-			}
+			$data['imagewhitelistenabled'] = (bool)$config->get( 'EnableImageWhitelist' );
 			$allowFrom = $config->get( 'AllowExternalImagesFrom' );
 			$allowException = !empty( $allowFrom );
 		}
@@ -161,13 +159,8 @@ class ApiQuerySiteinfo extends ApiQueryBase {
 			ApiResult::setIndexedTagName( $data['externalimages'], 'prefix' );
 		}
 
-		if ( !$config->get( 'DisableLangConversion' ) ) {
-			$data['langconversion'] = '';
-		}
-
-		if ( !$config->get( 'DisableTitleConversion' ) ) {
-			$data['titleconversion'] = '';
-		}
+		$data['langconversion'] = !$config->get( 'DisableLangConversion' );
+		$data['titleconversion'] = !$config->get( 'DisableTitleConversion' );
 
 		if ( $wgContLang->linkPrefixExtension() ) {
 			$linkPrefixCharset = $wgContLang->linkPrefixCharset();
@@ -180,11 +173,7 @@ class ApiQuerySiteinfo extends ApiQueryBase {
 		}
 
 		$linktrail = $wgContLang->linkTrail();
-		if ( $linktrail ) {
-			$data['linktrail'] = $linktrail;
-		} else {
-			$data['linktrail'] = '';
-		}
+		$data['linktrail'] = $linktrail ?: '';
 
 		$data['legaltitlechars'] = Title::legalChars();
 
@@ -224,18 +213,14 @@ class ApiQuerySiteinfo extends ApiQueryBase {
 			ApiResult::setIndexedTagName( $data['variants'], 'lang' );
 		}
 
-		if ( $wgContLang->isRTL() ) {
-			$data['rtl'] = '';
-		}
+		$data['rtl'] = $wgContLang->isRTL();
 		$data['fallback8bitEncoding'] = $wgContLang->fallback8bitEncoding();
 
-		if ( wfReadOnly() ) {
-			$data['readonly'] = '';
+		$data['readonly'] = wfReadOnly();
+		if ( $data['readonly'] ) {
 			$data['readonlyreason'] = wfReadOnlyReason();
 		}
-		if ( $config->get( 'EnableWriteAPI' ) ) {
-			$data['writeapi'] = '';
-		}
+		$data['writeapi'] = (bool)$config->get( 'EnableWriteAPI' );
 
 		$tz = $config->get( 'Localtimezone' );
 		$offset = $config->get( 'LocalTZoffset' );
@@ -251,20 +236,21 @@ class ApiQuerySiteinfo extends ApiQueryBase {
 		$data['scriptpath'] = $config->get( 'ScriptPath' );
 		$data['script'] = $config->get( 'Script' );
 		$data['variantarticlepath'] = $config->get( 'VariantArticlePath' );
+		$data[ApiResult::META_BC_BOOLS][] = 'variantarticlepath';
 		$data['server'] = $config->get( 'Server' );
 		$data['servername'] = $config->get( 'ServerName' );
 		$data['wikiid'] = wfWikiID();
 		$data['time'] = wfTimestamp( TS_ISO_8601, time() );
 
-		if ( $config->get( 'MiserMode' ) ) {
-			$data['misermode'] = '';
-		}
+		$data['misermode'] = (bool)$config->get( 'MiserMode' );
 
 		$data['maxuploadsize'] = UploadBase::getMaxUploadSize();
 
 		$data['thumblimits'] = $config->get( 'ThumbLimits' );
+		ApiResult::setArrayType( $data['thumblimits'], 'BCassoc' );
 		ApiResult::setIndexedTagName( $data['thumblimits'], 'limit' );
 		$data['imagelimits'] = array();
+		ApiResult::setArrayType( $data['imagelimits'], 'BCassoc' );
 		ApiResult::setIndexedTagName( $data['imagelimits'], 'limit' );
 		foreach ( $config->get( 'ImageLimits' ) as $k => $limit ) {
 			$data['imagelimits'][$k] = array( 'width' => $limit[0], 'height' => $limit[1] );
@@ -284,7 +270,9 @@ class ApiQuerySiteinfo extends ApiQueryBase {
 
 	protected function appendNamespaces( $property ) {
 		global $wgContLang;
-		$data = array();
+		$data = array(
+			ApiResult::META_TYPE => 'assoc',
+		);
 		foreach ( $wgContLang->getFormattedNamespaces() as $ns => $title ) {
 			$data[$ns] = array(
 				'id' => intval( $ns ),
@@ -293,21 +281,14 @@ class ApiQuerySiteinfo extends ApiQueryBase {
 			ApiResult::setContentValue( $data[$ns], 'name', $title );
 			$canonical = MWNamespace::getCanonicalName( $ns );
 
-			if ( MWNamespace::hasSubpages( $ns ) ) {
-				$data[$ns]['subpages'] = '';
-			}
+			$data[$ns]['subpages'] = MWNamespace::hasSubpages( $ns );
 
 			if ( $canonical ) {
 				$data[$ns]['canonical'] = strtr( $canonical, '_', ' ' );
 			}
 
-			if ( MWNamespace::isContent( $ns ) ) {
-				$data[$ns]['content'] = '';
-			}
-
-			if ( MWNamespace::isNonincludable( $ns ) ) {
-				$data[$ns]['nonincludable'] = '';
-			}
+			$data[$ns]['content'] = MWNamespace::isContent( $ns );
+			$data[$ns]['nonincludable'] = MWNamespace::isNonincludable( $ns );
 
 			$contentmodel = MWNamespace::getNamespaceContentModel( $ns );
 			if ( $contentmodel ) {
@@ -367,9 +348,7 @@ class ApiQuerySiteinfo extends ApiQueryBase {
 		foreach ( $wgContLang->getMagicWords() as $magicword => $aliases ) {
 			$caseSensitive = array_shift( $aliases );
 			$arr = array( 'name' => $magicword, 'aliases' => $aliases );
-			if ( $caseSensitive ) {
-				$arr['case-sensitive'] = '';
-			}
+			$arr['case-sensitive'] = (bool)$caseSensitive;
 			ApiResult::setIndexedTagName( $arr['aliases'], 'alias' );
 			$data[] = $arr;
 		}
@@ -402,20 +381,20 @@ class ApiQuerySiteinfo extends ApiQueryBase {
 			$val = array();
 			$val['prefix'] = $prefix;
 			if ( isset( $row['iw_local'] ) && $row['iw_local'] == '1' ) {
-				$val['local'] = '';
+				$val['local'] = true;
 			}
 			if ( isset( $row['iw_trans'] ) && $row['iw_trans'] == '1' ) {
-				$val['trans'] = '';
+				$val['trans'] = true;
 			}
 
 			if ( isset( $langNames[$prefix] ) ) {
 				$val['language'] = $langNames[$prefix];
 			}
 			if ( in_array( $prefix, $localInterwikis ) ) {
-				$val['localinterwiki'] = '';
+				$val['localinterwiki'] = true;
 			}
 			if ( in_array( $prefix, $extraLangPrefixes ) ) {
-				$val['extralanglink'] = '';
+				$val['extralanglink'] = true;
 
 				$linktext = wfMessage( "interlanguage-link-$prefix" );
 				if ( !$linktext->isDisabled() ) {
@@ -429,9 +408,7 @@ class ApiQuerySiteinfo extends ApiQueryBase {
 			}
 
 			$val['url'] = wfExpandUrl( $row['iw_url'], PROTO_CURRENT );
-			if ( substr( $row['iw_url'], 0, 2 ) == '//' ) {
-				$val['protorel'] = '';
-			}
+			$val['protorel'] = substr( $row['iw_url'], 0, 2 ) == '//';
 			if ( isset( $row['iw_wikiid'] ) && $row['iw_wikiid'] !== '' ) {
 				$val['wikiid'] = $row['iw_wikiid'];
 			}
@@ -747,10 +724,10 @@ class ApiQuerySiteinfo extends ApiQueryBase {
 			$skin = array( 'code' => $name );
 			ApiResult::setContentValue( $skin, 'name', $displayName );
 			if ( !isset( $allowed[$name] ) ) {
-				$skin['unusable'] = '';
+				$skin['unusable'] = true;
 			}
 			if ( $name === $default ) {
-				$skin['default'] = '';
+				$skin['default'] = true;
 			}
 			$data[] = $skin;
 		}
@@ -793,7 +770,9 @@ class ApiQuerySiteinfo extends ApiQueryBase {
 	}
 
 	public function appendDefaultOptions( $property ) {
-		return $this->getResult()->addValue( 'query', $property, User::getDefaultOptions() );
+		$options = User::getDefaultOptions();
+		$options[ApiResult::META_BC_BOOLS] = array_keys( $options );
+		return $this->getResult()->addValue( 'query', $property, $options );
 	}
 
 	private function formatParserTags( $item ) {
diff --git a/includes/api/ApiQueryTags.php b/includes/api/ApiQueryTags.php
index aa91216679..45f73b206a 100644
--- a/includes/api/ApiQueryTags.php
+++ b/includes/api/ApiQueryTags.php
@@ -108,8 +108,8 @@ class ApiQueryTags extends ApiQueryBase {
 			$isExtension = isset( $extensionDefinedTags[$tagName] );
 			$isExplicit = isset( $explicitlyDefinedTags[$tagName] );
 
-			if ( $fld_defined && ( $isExtension || $isExplicit ) ) {
-				$tag['defined'] = '';
+			if ( $fld_defined ) {
+				$tag['defined'] = $isExtension || $isExplicit;
 			}
 
 			if ( $fld_source ) {
@@ -122,10 +122,8 @@ class ApiQueryTags extends ApiQueryBase {
 				}
 			}
 
-			if ( $fld_active &&
-				( $isExplicit || isset( $extensionActivatedTags[$tagName] ) )
-			) {
-				$tag['active'] = '';
+			if ( $fld_active ) {
+				$tag['active'] = $isExplicit || isset( $extensionActivatedTags[$tagName] );
 			}
 
 			$fit = $result->addValue( array( 'query', $this->getModuleName() ), null, $tag );
diff --git a/includes/api/ApiQueryTokens.php b/includes/api/ApiQueryTokens.php
index f8eee8dfcd..65a08a3b97 100644
--- a/includes/api/ApiQueryTokens.php
+++ b/includes/api/ApiQueryTokens.php
@@ -35,7 +35,9 @@ class ApiQueryTokens extends ApiQueryBase {
 
 	public function execute() {
 		$params = $this->extractRequestParams();
-		$res = array();
+		$res = array(
+			ApiResult::META_TYPE => 'assoc',
+		);
 
 		if ( $this->lacksSameOriginSecurity() ) {
 			$this->setWarning( 'Tokens may not be obtained when the same-origin policy is not applied' );
diff --git a/includes/api/ApiQueryUserContributions.php b/includes/api/ApiQueryUserContributions.php
index f6c63560f9..e5ec67d0fd 100644
--- a/includes/api/ApiQueryUserContributions.php
+++ b/includes/api/ApiQueryUserContributions.php
@@ -335,7 +335,7 @@ class ApiQueryContributions extends ApiQueryBase {
 		$anyHidden = false;
 
 		if ( $row->rev_deleted & Revision::DELETED_TEXT ) {
-			$vals['texthidden'] = '';
+			$vals['texthidden'] = true;
 			$anyHidden = true;
 		}
 
@@ -343,7 +343,7 @@ class ApiQueryContributions extends ApiQueryBase {
 		$vals['userid'] = $row->rev_user;
 		$vals['user'] = $row->rev_user_text;
 		if ( $row->rev_deleted & Revision::DELETED_USER ) {
-			$vals['userhidden'] = '';
+			$vals['userhidden'] = true;
 			$anyHidden = true;
 		}
 		if ( $this->fld_ids ) {
@@ -367,20 +367,14 @@ class ApiQueryContributions extends ApiQueryBase {
 		}
 
 		if ( $this->fld_flags ) {
-			if ( $row->rev_parent_id == 0 && !is_null( $row->rev_parent_id ) ) {
-				$vals['new'] = '';
-			}
-			if ( $row->rev_minor_edit ) {
-				$vals['minor'] = '';
-			}
-			if ( $row->page_latest == $row->rev_id ) {
-				$vals['top'] = '';
-			}
+			$vals['new'] = $row->rev_parent_id == 0 && !is_null( $row->rev_parent_id );
+			$vals['minor'] = (bool)$row->rev_minor_edit;
+			$vals['top'] = $row->page_latest == $row->rev_id;
 		}
 
 		if ( ( $this->fld_comment || $this->fld_parsedcomment ) && isset( $row->rev_comment ) ) {
 			if ( $row->rev_deleted & Revision::DELETED_COMMENT ) {
-				$vals['commenthidden'] = '';
+				$vals['commenthidden'] = true;
 				$anyHidden = true;
 			}
 
@@ -400,8 +394,8 @@ class ApiQueryContributions extends ApiQueryBase {
 			}
 		}
 
-		if ( $this->fld_patrolled && $row->rc_patrolled ) {
-			$vals['patrolled'] = '';
+		if ( $this->fld_patrolled ) {
+			$vals['patrolled'] = (bool)$row->rc_patrolled;
 		}
 
 		if ( $this->fld_size && !is_null( $row->rev_len ) ) {
@@ -429,7 +423,7 @@ class ApiQueryContributions extends ApiQueryBase {
 		}
 
 		if ( $anyHidden && $row->rev_deleted & Revision::DELETED_RESTRICTED ) {
-			$vals['suppressed'] = '';
+			$vals['suppressed'] = true;
 		}
 
 		return $vals;
diff --git a/includes/api/ApiQueryUserInfo.php b/includes/api/ApiQueryUserInfo.php
index fd095fcc3c..3d3590c54f 100644
--- a/includes/api/ApiQueryUserInfo.php
+++ b/includes/api/ApiQueryUserInfo.php
@@ -61,7 +61,7 @@ class ApiQueryUserInfo extends ApiQueryBase {
 		$vals['name'] = $user->getName();
 
 		if ( $user->isAnon() ) {
-			$vals['anon'] = '';
+			$vals['anon'] = true;
 		}
 
 		if ( isset( $this->prop['blockinfo'] ) ) {
@@ -78,23 +78,26 @@ class ApiQueryUserInfo extends ApiQueryBase {
 			}
 		}
 
-		if ( isset( $this->prop['hasmsg'] ) && $user->getNewtalk() ) {
-			$vals['messages'] = '';
+		if ( isset( $this->prop['hasmsg'] ) ) {
+			$vals['messages'] = $user->getNewtalk();
 		}
 
 		if ( isset( $this->prop['groups'] ) ) {
 			$vals['groups'] = $user->getEffectiveGroups();
+			ApiResult::setArrayType( $vals['groups'], 'array' ); // even if empty
 			ApiResult::setIndexedTagName( $vals['groups'], 'g' ); // even if empty
 		}
 
 		if ( isset( $this->prop['implicitgroups'] ) ) {
 			$vals['implicitgroups'] = $user->getAutomaticGroups();
+			ApiResult::setArrayType( $vals['implicitgroups'], 'array' ); // even if empty
 			ApiResult::setIndexedTagName( $vals['implicitgroups'], 'g' ); // even if empty
 		}
 
 		if ( isset( $this->prop['rights'] ) ) {
 			// User::getRights() may return duplicate values, strip them
 			$vals['rights'] = array_values( array_unique( $user->getRights() ) );
+			ApiResult::setArrayType( $vals['rights'], 'array' ); // even if empty
 			ApiResult::setIndexedTagName( $vals['rights'], 'r' ); // even if empty
 		}
 
@@ -108,6 +111,7 @@ class ApiQueryUserInfo extends ApiQueryBase {
 
 		if ( isset( $this->prop['options'] ) ) {
 			$vals['options'] = $user->getOptions();
+			$vals['options'][ApiResult::META_BC_BOOLS] = array_keys( $vals['options'] );
 		}
 
 		if ( isset( $this->prop['preferencestoken'] ) ) {
@@ -191,9 +195,13 @@ class ApiQueryUserInfo extends ApiQueryBase {
 	}
 
 	protected function getRateLimits() {
+		$retval = array(
+			ApiResult::META_TYPE => 'assoc',
+		);
+
 		$user = $this->getUser();
 		if ( !$user->isPingLimitable() ) {
-			return array(); // No limits
+			return $retval; // No limits
 		}
 
 		// Find out which categories we belong to
@@ -213,7 +221,6 @@ class ApiQueryUserInfo extends ApiQueryBase {
 		$categories = array_merge( $categories, $user->getGroups() );
 
 		// Now get the actual limits
-		$retval = array();
 		foreach ( $this->getConfig()->get( 'RateLimits' ) as $action => $limits ) {
 			foreach ( $categories as $cat ) {
 				if ( isset( $limits[$cat] ) && !is_null( $limits[$cat] ) ) {
diff --git a/includes/api/ApiQueryUsers.php b/includes/api/ApiQueryUsers.php
index e2c47f54f2..f22c21340e 100644
--- a/includes/api/ApiQueryUsers.php
+++ b/includes/api/ApiQueryUsers.php
@@ -110,7 +110,7 @@ class ApiQueryUsers extends ApiQueryBase {
 		foreach ( $users as $u ) {
 			$n = User::getCanonicalName( $u );
 			if ( $n === false || $n === '' ) {
-				$vals = array( 'name' => $u, 'invalid' => '' );
+				$vals = array( 'name' => $u, 'invalid' => true );
 				$fit = $result->addValue( array( 'query', $this->getModuleName() ),
 					null, $vals );
 				if ( !$fit ) {
@@ -190,7 +190,7 @@ class ApiQueryUsers extends ApiQueryBase {
 					$data[$name]['rights'] = $user->getRights();
 				}
 				if ( $row->ipb_deleted ) {
-					$data[$name]['hidden'] = '';
+					$data[$name]['hidden'] = true;
 				}
 				if ( isset( $this->prop['blockinfo'] ) && !is_null( $row->ipb_by_text ) ) {
 					$data[$name]['blockid'] = $row->ipb_id;
@@ -201,8 +201,8 @@ class ApiQueryUsers extends ApiQueryBase {
 					$data[$name]['blockexpiry'] = $row->ipb_expiry;
 				}
 
-				if ( isset( $this->prop['emailable'] ) && $user->canReceiveEmail() ) {
-					$data[$name]['emailable'] = '';
+				if ( isset( $this->prop['emailable'] ) ) {
+					$data[$name]['emailable'] = $user->canReceiveEmail();
 				}
 
 				if ( isset( $this->prop['gender'] ) ) {
@@ -237,7 +237,7 @@ class ApiQueryUsers extends ApiQueryBase {
 				$iwUser = $urPage->fetchUser( $u );
 
 				if ( $iwUser instanceof UserRightsProxy ) {
-					$data[$u]['interwiki'] = '';
+					$data[$u]['interwiki'] = true;
 
 					if ( !is_null( $params['token'] ) ) {
 						$tokenFunctions = $this->getTokenFunctions();
@@ -252,16 +252,19 @@ class ApiQueryUsers extends ApiQueryBase {
 						}
 					}
 				} else {
-					$data[$u]['missing'] = '';
+					$data[$u]['missing'] = true;
 				}
 			} else {
 				if ( isset( $this->prop['groups'] ) && isset( $data[$u]['groups'] ) ) {
+					ApiResult::setArrayType( $data[$u]['groups'], 'array' );
 					ApiResult::setIndexedTagName( $data[$u]['groups'], 'g' );
 				}
 				if ( isset( $this->prop['implicitgroups'] ) && isset( $data[$u]['implicitgroups'] ) ) {
+					ApiResult::setArrayType( $data[$u]['implicitgroups'], 'array' );
 					ApiResult::setIndexedTagName( $data[$u]['implicitgroups'], 'g' );
 				}
 				if ( isset( $this->prop['rights'] ) && isset( $data[$u]['rights'] ) ) {
+					ApiResult::setArrayType( $data[$u]['rights'], 'array' );
 					ApiResult::setIndexedTagName( $data[$u]['rights'], 'r' );
 				}
 			}
diff --git a/includes/api/ApiQueryWatchlist.php b/includes/api/ApiQueryWatchlist.php
index bd1ed0a1fc..9f7387c710 100644
--- a/includes/api/ApiQueryWatchlist.php
+++ b/includes/api/ApiQueryWatchlist.php
@@ -307,7 +307,7 @@ class ApiQueryWatchlist extends ApiQueryGeneratorBase {
 		if ( $this->fld_title || $this->fld_ids ) {
 			// These should already have been filtered out of the query, but just in case.
 			if ( $type === RC_LOG && ( $row->rc_deleted & LogPage::DELETED_ACTION ) ) {
-				$vals['actionhidden'] = '';
+				$vals['actionhidden'] = true;
 				$anyHidden = true;
 			}
 			if ( $type !== RC_LOG ||
@@ -327,7 +327,7 @@ class ApiQueryWatchlist extends ApiQueryGeneratorBase {
 		/* Add user data and 'anon' flag, if user is anonymous. */
 		if ( $this->fld_user || $this->fld_userid ) {
 			if ( $row->rc_deleted & Revision::DELETED_USER ) {
-				$vals['userhidden'] = '';
+				$vals['userhidden'] = true;
 				$anyHidden = true;
 			}
 			if ( Revision::userCanBitfield( $row->rc_deleted, Revision::DELETED_USER, $user ) ) {
@@ -342,22 +342,16 @@ class ApiQueryWatchlist extends ApiQueryGeneratorBase {
 				}
 
 				if ( !$row->rc_user ) {
-					$vals['anon'] = '';
+					$vals['anon'] = true;
 				}
 			}
 		}
 
 		/* Add flags, such as new, minor, bot. */
 		if ( $this->fld_flags ) {
-			if ( $row->rc_bot ) {
-				$vals['bot'] = '';
-			}
-			if ( $row->rc_type == RC_NEW ) {
-				$vals['new'] = '';
-			}
-			if ( $row->rc_minor ) {
-				$vals['minor'] = '';
-			}
+			$vals['bot'] = (bool)$row->rc_bot;
+			$vals['new'] = $row->rc_type == RC_NEW;
+			$vals['minor'] = (bool)$row->rc_minor;
 		}
 
 		/* Add sizes of each revision. (Only available on 1.10+) */
@@ -380,7 +374,7 @@ class ApiQueryWatchlist extends ApiQueryGeneratorBase {
 		/* Add edit summary / log summary. */
 		if ( $this->fld_comment || $this->fld_parsedcomment ) {
 			if ( $row->rc_deleted & Revision::DELETED_COMMENT ) {
-				$vals['commenthidden'] = '';
+				$vals['commenthidden'] = true;
 				$anyHidden = true;
 			}
 			if ( Revision::userCanBitfield( $row->rc_deleted, Revision::DELETED_COMMENT, $user ) ) {
@@ -395,17 +389,14 @@ class ApiQueryWatchlist extends ApiQueryGeneratorBase {
 		}
 
 		/* Add the patrolled flag */
-		if ( $this->fld_patrol && $row->rc_patrolled == 1 ) {
-			$vals['patrolled'] = '';
-		}
-
-		if ( $this->fld_patrol && ChangesList::isUnpatrolled( $row, $user ) ) {
-			$vals['unpatrolled'] = '';
+		if ( $this->fld_patrol ) {
+			$vals['patrolled'] = $row->rc_patrolled == 1;
+			$vals['unpatrolled'] = ChangesList::isUnpatrolled( $row, $user );
 		}
 
 		if ( $this->fld_loginfo && $row->rc_type == RC_LOG ) {
 			if ( $row->rc_deleted & LogPage::DELETED_ACTION ) {
-				$vals['actionhidden'] = '';
+				$vals['actionhidden'] = true;
 				$anyHidden = true;
 			}
 			if ( LogEventsList::userCanBitfield( $row->rc_deleted, LogPage::DELETED_ACTION, $user ) ) {
@@ -417,7 +408,7 @@ class ApiQueryWatchlist extends ApiQueryGeneratorBase {
 		}
 
 		if ( $anyHidden && ( $row->rc_deleted & Revision::DELETED_RESTRICTED ) ) {
-			$vals['suppressed'] = '';
+			$vals['suppressed'] = true;
 		}
 
 		return $vals;
diff --git a/includes/api/ApiResult.php b/includes/api/ApiResult.php
index 490b8310dc..5db8ca71ad 100644
--- a/includes/api/ApiResult.php
+++ b/includes/api/ApiResult.php
@@ -180,7 +180,9 @@ class ApiResult implements ApiSerializable {
 	 * Clear the current result data.
 	 */
 	public function reset() {
-		$this->data = array();
+		$this->data = array(
+			self::META_TYPE => 'assoc', // Usually what's desired
+		);
 		$this->size = 0;
 	}
 
@@ -1242,7 +1244,7 @@ class ApiResult implements ApiSerializable {
 	}
 
 	/**
-	 * Alias for self::defineIndexedTagName()
+	 * Alias for self::addIndexedTagName()
 	 * @deprecated since 1.25, use $this->addIndexedTagName() instead
 	 * @param array $path Path to the array, like addValue()'s $path
 	 * @param string $tag
diff --git a/includes/api/ApiSetNotificationTimestamp.php b/includes/api/ApiSetNotificationTimestamp.php
index e41ee070a8..86a3f6aa04 100644
--- a/includes/api/ApiSetNotificationTimestamp.php
+++ b/includes/api/ApiSetNotificationTimestamp.php
@@ -115,21 +115,21 @@ class ApiSetNotificationTimestamp extends ApiBase {
 			foreach ( $pageSet->getInvalidTitles() as $title ) {
 				$r = array();
 				$r['title'] = $title;
-				$r['invalid'] = '';
+				$r['invalid'] = true;
 				$result[] = $r;
 			}
 			foreach ( $pageSet->getMissingPageIDs() as $p ) {
 				$page = array();
 				$page['pageid'] = $p;
-				$page['missing'] = '';
-				$page['notwatched'] = '';
+				$page['missing'] = true;
+				$page['notwatched'] = true;
 				$result[] = $page;
 			}
 			foreach ( $pageSet->getMissingRevisionIDs() as $r ) {
 				$rev = array();
 				$rev['revid'] = $r;
-				$rev['missing'] = '';
-				$rev['notwatched'] = '';
+				$rev['missing'] = true;
+				$rev['notwatched'] = true;
 				$result[] = $rev;
 			}
 
@@ -163,7 +163,7 @@ class ApiSetNotificationTimestamp extends ApiBase {
 						'title' => $title->getPrefixedText(),
 					);
 					if ( !$title->exists() ) {
-						$r['missing'] = '';
+						$r['missing'] = true;
 					}
 					if ( isset( $timestamps[$ns] ) && array_key_exists( $dbkey, $timestamps[$ns] ) ) {
 						$r['notificationtimestamp'] = '';
@@ -171,7 +171,7 @@ class ApiSetNotificationTimestamp extends ApiBase {
 							$r['notificationtimestamp'] = wfTimestamp( TS_ISO_8601, $timestamps[$ns][$dbkey] );
 						}
 					} else {
-						$r['notwatched'] = '';
+						$r['notwatched'] = true;
 					}
 					$result[] = $r;
 				}
diff --git a/includes/api/ApiTokens.php b/includes/api/ApiTokens.php
index 9eb40209e6..4d7fc5a087 100644
--- a/includes/api/ApiTokens.php
+++ b/includes/api/ApiTokens.php
@@ -37,7 +37,9 @@ class ApiTokens extends ApiBase {
 		$this->logFeatureUsage( "action=tokens" );
 
 		$params = $this->extractRequestParams();
-		$res = array();
+		$res = array(
+			ApiResult::META_TYPE => 'assoc',
+		);
 
 		$types = $this->getTokenTypes();
 		foreach ( $params['type'] as $type ) {
diff --git a/includes/api/ApiWatch.php b/includes/api/ApiWatch.php
index 6a585d4f17..85d051def5 100644
--- a/includes/api/ApiWatch.php
+++ b/includes/api/ApiWatch.php
@@ -109,15 +109,15 @@ class ApiWatch extends ApiBase {
 
 		if ( $params['unwatch'] ) {
 			$status = UnwatchAction::doUnwatch( $title, $user );
+			$res['unwatched'] = $status->isOK();
 			if ( $status->isOK() ) {
-				$res['unwatched'] = '';
 				$res['message'] = $this->msg( 'removedwatchtext', $title->getPrefixedText() )
 					->title( $title )->parseAsBlock();
 			}
 		} else {
 			$status = WatchAction::doWatch( $title, $user );
+			$res['watched'] = $status->isOK();
 			if ( $status->isOK() ) {
-				$res['watched'] = '';
 				$res['message'] = $this->msg( 'addedwatchtext', $title->getPrefixedText() )
 					->title( $title )->parseAsBlock();
 			}
diff --git a/tests/phpunit/includes/api/ApiContinuationManagerTest.php b/tests/phpunit/includes/api/ApiContinuationManagerTest.php
index ea08c02847..2edf0c6fb1 100644
--- a/tests/phpunit/includes/api/ApiContinuationManagerTest.php
+++ b/tests/phpunit/includes/api/ApiContinuationManagerTest.php
@@ -84,7 +84,7 @@ class ApiContinuationManagerTest extends MediaWikiTestCase {
 			'gcontinue' => 3,
 			'continue' => 'gcontinue||',
 		), $result->getResultData( 'continue' ) );
-		$this->assertSame( '', $result->getResultData( 'batchcomplete' ) );
+		$this->assertSame( true, $result->getResultData( 'batchcomplete' ) );
 
 		$manager = self::getManager( '', $allModules, array( 'mock1', 'mock2' ) );
 		$this->assertSame( false, $manager->isGeneratorDone() );
diff --git a/tests/phpunit/includes/api/ApiErrorFormatterTest.php b/tests/phpunit/includes/api/ApiErrorFormatterTest.php
index 344af62fdd..8ebdf60f5f 100644
--- a/tests/phpunit/includes/api/ApiErrorFormatterTest.php
+++ b/tests/phpunit/includes/api/ApiErrorFormatterTest.php
@@ -15,6 +15,11 @@ class ApiErrorFormatterTest extends MediaWikiTestCase {
 		$result = new ApiResult( 8388608 );
 		$formatter = new ApiErrorFormatter( $result, Language::factory( $lang ), $format, $useDB );
 
+		// Add default type
+		$expect1[ApiResult::META_TYPE] = 'assoc';
+		$expect2[ApiResult::META_TYPE] = 'assoc';
+		$expect3[ApiResult::META_TYPE] = 'assoc';
+
 		$formatter->addWarning( 'string', 'mainpage' );
 		$formatter->addError( 'err', 'mainpage' );
 		$this->assertSame( $expect1, $result->getResultData(), 'Simple test' );
@@ -262,6 +267,7 @@ class ApiErrorFormatterTest extends MediaWikiTestCase {
 					ApiResult::META_CONTENT => 'warnings',
 				),
 			),
+			ApiResult::META_TYPE => 'assoc',
 		), $result->getResultData(), 'Simple test' );
 
 		$result->reset();
@@ -293,6 +299,7 @@ class ApiErrorFormatterTest extends MediaWikiTestCase {
 					ApiResult::META_CONTENT => 'warnings',
 				),
 			),
+			ApiResult::META_TYPE => 'assoc',
 		), $result->getResultData(), 'Complex test' );
 
 		$result->reset();
@@ -315,6 +322,7 @@ class ApiErrorFormatterTest extends MediaWikiTestCase {
 					ApiResult::META_CONTENT => 'warnings',
 				),
 			),
+			ApiResult::META_TYPE => 'assoc',
 		), $result->getResultData(), 'Status test' );
 
 		$I = ApiResult::META_INDEXED_TAG_NAME;
diff --git a/tests/phpunit/includes/api/ApiResultTest.php b/tests/phpunit/includes/api/ApiResultTest.php
index 7e43a240a7..03d058a7cf 100644
--- a/tests/phpunit/includes/api/ApiResultTest.php
+++ b/tests/phpunit/includes/api/ApiResultTest.php
@@ -144,7 +144,12 @@ class ApiResultTest extends MediaWikiTestCase {
 		$result2 = new ApiResult( 8388608 );
 		$result2->addValue( null, 'foo', 'bar' );
 		ApiResult::setValue( $arr, 'baz', $result2 );
-		$this->assertSame( array( 'baz' => array( 'foo' => 'bar' ) ), $arr );
+		$this->assertSame( array(
+			'baz' => array(
+				ApiResult::META_TYPE => 'assoc',
+				'foo' => 'bar',
+			)
+		), $arr );
 
 		$arr = array();
 		ApiResult::setValue( $arr, 'foo', "foo\x80bar" );
@@ -182,6 +187,7 @@ class ApiResultTest extends MediaWikiTestCase {
 			'unnamed 2',
 			'a' => array( 'b' => array() ),
 			'setContentValue' => '3',
+			ApiResult::META_TYPE => 'assoc',
 			ApiResult::META_CONTENT => 'setContentValue',
 		), $result->getResultData() );
 		$this->assertSame( 20, $result->getSize() );
@@ -217,7 +223,9 @@ class ApiResultTest extends MediaWikiTestCase {
 			$result->getResultData( array( ApiResult::META_CONTENT ) ) );
 
 		$result->reset();
-		$this->assertSame( array(), $result->getResultData() );
+		$this->assertSame( array(
+			ApiResult::META_TYPE => 'assoc',
+		), $result->getResultData() );
 		$this->assertSame( 0, $result->getSize() );
 
 		$result->addValue( null, 'foo', 1 );
@@ -227,7 +235,7 @@ class ApiResultTest extends MediaWikiTestCase {
 		$result->addValue( null, 'bottom', '2' );
 		$result->addValue( null, 'foo', '2', ApiResult::OVERRIDE );
 		$result->addValue( null, 'bar', '2', ApiResult::OVERRIDE | ApiResult::ADD_ON_TOP );
-		$this->assertSame( array( 0, 'top', 'foo', 'bar', 'bottom' ),
+		$this->assertSame( array( 0, 'top', 'foo', 'bar', 'bottom', ApiResult::META_TYPE ),
 			array_keys( $result->getResultData() ) );
 
 		$result->reset();
@@ -240,8 +248,10 @@ class ApiResultTest extends MediaWikiTestCase {
 		$result->reset();
 		$result->addValue( null, 'sub', array( 'foo' => 1 ) );
 		$result->addValue( null, 'sub', array( 'bar' => 1 ) );
-		$this->assertSame( array( 'sub' => array( 'foo' => 1, 'bar' => 1 ) ),
-			$result->getResultData() );
+		$this->assertSame( array(
+			'sub' => array( 'foo' => 1, 'bar' => 1 ),
+			ApiResult::META_TYPE => 'assoc',
+		), $result->getResultData() );
 
 		try {
 			$result->addValue( null, 'sub', array( 'foo' => 2, 'baz' => 2 ) );
@@ -264,6 +274,7 @@ class ApiResultTest extends MediaWikiTestCase {
 		$this->assertSame( array(
 			'title' => (string)$title,
 			'obj' => array( 'foo' => 1, 'bar' => 2, ApiResult::META_TYPE => 'assoc' ),
+			ApiResult::META_TYPE => 'assoc',
 		), $result->getResultData() );
 
 		$fh = tmpfile();
@@ -313,9 +324,15 @@ class ApiResultTest extends MediaWikiTestCase {
 
 		$result->reset();
 		$result->addParsedLimit( 'foo', 12 );
-		$this->assertSame( array( 'limits' => array( 'foo' => 12 ) ), $result->getResultData() );
+		$this->assertSame( array(
+			'limits' => array( 'foo' => 12 ),
+			ApiResult::META_TYPE => 'assoc',
+		), $result->getResultData() );
 		$result->addParsedLimit( 'foo', 13 );
-		$this->assertSame( array( 'limits' => array( 'foo' => 13 ) ), $result->getResultData() );
+		$this->assertSame( array(
+			'limits' => array( 'foo' => 13 ),
+			ApiResult::META_TYPE => 'assoc',
+		), $result->getResultData() );
 		$this->assertSame( null, $result->getResultData( array( 'foo', 'bar', 'baz' ) ) );
 		$this->assertSame( 13, $result->getResultData( array( 'limits', 'foo' ) ) );
 		try {
@@ -345,7 +362,13 @@ class ApiResultTest extends MediaWikiTestCase {
 		$result2 = new ApiResult( 8388608 );
 		$result2->addValue( null, 'foo', 'bar' );
 		$result->addValue( null, 'baz', $result2 );
-		$this->assertSame( array( 'baz' => array( 'foo' => 'bar' ) ), $result->getResultData() );
+		$this->assertSame( array(
+			'baz' => array(
+				'foo' => 'bar',
+				ApiResult::META_TYPE => 'assoc',
+			),
+			ApiResult::META_TYPE => 'assoc',
+		), $result->getResultData() );
 
 		$result = new ApiResult( 8388608 );
 		$result->addValue( null, 'foo', "foo\x80bar" );
@@ -355,6 +378,7 @@ class ApiResultTest extends MediaWikiTestCase {
 			'foo' => "foo\xef\xbf\xbdbar",
 			'bar' => "\xc3\xa1",
 			'baz' => 74,
+			ApiResult::META_TYPE => 'assoc',
 		), $result->getResultData() );
 	}
 
@@ -403,7 +427,7 @@ class ApiResultTest extends MediaWikiTestCase {
 		$result->removePreserveKeysList( null, 'baz' );
 		$result->addArrayTypeRecursive( null, 'default' );
 		$result->addArrayType( null, 'array' );
-		$this->assertSame( $expect, $result->getResultData() );
+		$this->assertEquals( $expect, $result->getResultData() );
 
 		$arr = array( 'foo' => array( 'bar' => array() ) );
 		$expect = array(
@@ -1211,7 +1235,7 @@ class ApiResultTest extends MediaWikiTestCase {
 			'gcontinue' => 3,
 			'continue' => 'gcontinue||',
 		), $result->getResultData( 'continue' ) );
-		$this->assertSame( '', $result->getResultData( 'batchcomplete' ) );
+		$this->assertSame( true, $result->getResultData( 'batchcomplete' ) );
 		$this->assertSame( array(
 			'mocklist' => array( 'mlcontinue' => 2 ),
 			'generator' => array( 'gcontinue' => 3 ),
@@ -1229,7 +1253,7 @@ class ApiResultTest extends MediaWikiTestCase {
 			'gcontinue' => 3,
 			'continue' => 'gcontinue||mocklist',
 		), $result->getResultData( 'continue' ) );
-		$this->assertSame( '', $result->getResultData( 'batchcomplete' ) );
+		$this->assertSame( true, $result->getResultData( 'batchcomplete' ) );
 		$this->assertSame( array(
 			'generator' => array( 'gcontinue' => 3 ),
 		), $result->getResultData( 'query-continue' ) );
@@ -1283,7 +1307,7 @@ class ApiResultTest extends MediaWikiTestCase {
 			'mlcontinue' => 2,
 			'continue' => '-||mock1|mock2',
 		), $result->getResultData( 'continue' ) );
-		$this->assertSame( '', $result->getResultData( 'batchcomplete' ) );
+		$this->assertSame( true, $result->getResultData( 'batchcomplete' ) );
 		$this->assertSame( array(
 			'mocklist' => array( 'mlcontinue' => 2 ),
 		), $result->getResultData( 'query-continue' ) );
@@ -1296,7 +1320,7 @@ class ApiResultTest extends MediaWikiTestCase {
 		$result->endContinuation( 'raw' );
 		$result->endContinuation( 'standard' );
 		$this->assertSame( null, $result->getResultData( 'continue' ) );
-		$this->assertSame( '', $result->getResultData( 'batchcomplete' ) );
+		$this->assertSame( true, $result->getResultData( 'batchcomplete' ) );
 		$this->assertSame( null, $result->getResultData( 'query-continue' ) );
 		$main->setContinuationManager( null );
 
diff --git a/tests/phpunit/includes/api/format/ApiFormatTestBase.php b/tests/phpunit/includes/api/format/ApiFormatTestBase.php
index 67949ab9f2..cabf62b18a 100644
--- a/tests/phpunit/includes/api/format/ApiFormatTestBase.php
+++ b/tests/phpunit/includes/api/format/ApiFormatTestBase.php
@@ -33,6 +33,7 @@ abstract class ApiFormatTestBase extends MediaWikiTestCase {
 			$main->getModuleManager()->addModule( $this->printerName, 'format', $class );
 		}
 		$result = $main->getResult();
+		$result->addArrayType( null, 'default' );
 		foreach ( $data as $k => $v ) {
 			$result->addValue( null, $k, $v );
 		}
diff --git a/tests/phpunit/includes/api/query/ApiQueryContinue2Test.php b/tests/phpunit/includes/api/query/ApiQueryContinue2Test.php
index 243176139a..cd735223c2 100644
--- a/tests/phpunit/includes/api/query/ApiQueryContinue2Test.php
+++ b/tests/phpunit/includes/api/query/ApiQueryContinue2Test.php
@@ -61,7 +61,7 @@ class ApiQueryContinue2Test extends ApiQueryContinueTestBase {
 		};
 		// generator + 1 prop + 1 list
 		$data = $this->query( $mk( 99, 99, true ), 1, 'g1p', false ) +
-			array( 'batchcomplete' => '' );
+			array( 'batchcomplete' => true );
 		$this->checkC( $data, $mk( 1, 1, true ), 6, 'g1p-11t' );
 		$this->checkC( $data, $mk( 2, 2, true ), 3, 'g1p-22t' );
 		$this->checkC( $data, $mk( 1, 1, false ), 6, 'g1p-11f' );
diff --git a/tests/phpunit/includes/api/query/ApiQueryContinueTest.php b/tests/phpunit/includes/api/query/ApiQueryContinueTest.php
index de9965b6e9..d441f4c406 100644
--- a/tests/phpunit/includes/api/query/ApiQueryContinueTest.php
+++ b/tests/phpunit/includes/api/query/ApiQueryContinueTest.php
@@ -67,7 +67,7 @@ class ApiQueryContinueTest extends ApiQueryContinueTestBase {
 			);
 		};
 		$data = $this->query( $mk( 99 ), 1, '1L', false ) +
-			array( 'batchcomplete' => '' );
+			array( 'batchcomplete' => true );
 
 		// 1 list
 		$this->checkC( $data, $mk( 1 ), 5, '1L-1' );
@@ -95,7 +95,7 @@ class ApiQueryContinueTest extends ApiQueryContinueTestBase {
 		};
 		// 2 lists
 		$data = $this->query( $mk( 99, 99 ), 1, '2L', false ) +
-			array( 'batchcomplete' => '' );
+			array( 'batchcomplete' => true );
 		$this->checkC( $data, $mk( 1, 1 ), 5, '2L-11' );
 		$this->checkC( $data, $mk( 2, 2 ), 3, '2L-22' );
 		$this->checkC( $data, $mk( 3, 3 ), 2, '2L-33' );
@@ -120,7 +120,7 @@ class ApiQueryContinueTest extends ApiQueryContinueTestBase {
 		};
 		// generator + 1 prop
 		$data = $this->query( $mk( 99, 99 ), 1, 'G1P', false ) +
-			array( 'batchcomplete' => '' );
+			array( 'batchcomplete' => true );
 		$this->checkC( $data, $mk( 1, 1 ), 11, 'G1P-11' );
 		$this->checkC( $data, $mk( 2, 2 ), 6, 'G1P-22' );
 		$this->checkC( $data, $mk( 3, 3 ), 4, 'G1P-33' );
@@ -146,7 +146,7 @@ class ApiQueryContinueTest extends ApiQueryContinueTestBase {
 		};
 		// generator + 2 props
 		$data = $this->query( $mk( 99, 99, 99 ), 1, 'G2P', false ) +
-			array( 'batchcomplete' => '' );
+			array( 'batchcomplete' => true );
 		$this->checkC( $data, $mk( 1, 1, 1 ), 16, 'G2P-111' );
 		$this->checkC( $data, $mk( 2, 2, 2 ), 9, 'G2P-222' );
 		$this->checkC( $data, $mk( 3, 3, 3 ), 6, 'G2P-333' );
@@ -180,7 +180,7 @@ class ApiQueryContinueTest extends ApiQueryContinueTestBase {
 		};
 		// generator + 1 prop + 1 list
 		$data = $this->query( $mk( 99, 99, 99 ), 1, 'G1P1L', false ) +
-			array( 'batchcomplete' => '' );
+			array( 'batchcomplete' => true );
 		$this->checkC( $data, $mk( 1, 1, 1 ), 11, 'G1P1L-111' );
 		$this->checkC( $data, $mk( 2, 2, 2 ), 6, 'G1P1L-222' );
 		$this->checkC( $data, $mk( 3, 3, 3 ), 4, 'G1P1L-333' );
@@ -218,7 +218,7 @@ class ApiQueryContinueTest extends ApiQueryContinueTestBase {
 		};
 		// generator + 1 prop + 1 list
 		$data = $this->query( $mk( 99, 99, 99, 99, 99 ), 1, 'G2P2L1M', false ) +
-			array( 'batchcomplete' => '' );
+			array( 'batchcomplete' => true );
 		$this->checkC( $data, $mk( 1, 1, 1, 1, 1 ), 16, 'G2P2L1M-11111' );
 		$this->checkC( $data, $mk( 2, 2, 2, 2, 2 ), 9, 'G2P2L1M-22222' );
 		$this->checkC( $data, $mk( 3, 3, 3, 3, 3 ), 6, 'G2P2L1M-33333' );
@@ -249,7 +249,7 @@ class ApiQueryContinueTest extends ApiQueryContinueTestBase {
 		};
 		// generator + 1 prop
 		$data = $this->query( $mk( 99, true, 99, true ), 1, 'G=P', false ) +
-			array( 'batchcomplete' => '' );
+			array( 'batchcomplete' => true );
 
 		$this->checkC( $data, $mk( 1, true, 1, true ), 4, 'G=P-1t1t' );
 		$this->checkC( $data, $mk( 2, true, 2, true ), 2, 'G=P-2t2t' );
@@ -296,7 +296,7 @@ class ApiQueryContinueTest extends ApiQueryContinueTestBase {
 		};
 		// generator + 1 list
 		$data = $this->query( $mk( 99, true, 99, true ), 1, 'G=L', false ) +
-			array( 'batchcomplete' => '' );
+			array( 'batchcomplete' => true );
 
 		$this->checkC( $data, $mk( 1, true, 1, true ), 5, 'G=L-1t1t' );
 		$this->checkC( $data, $mk( 2, true, 2, true ), 3, 'G=L-2t2t' );
-- 
2.20.1