From cdc36570eadae18ef367be34a901f3c21b742557 Mon Sep 17 00:00:00 2001
From: "This, that and the other" <at.light@live.com.au>
Date: Sat, 10 Oct 2015 19:51:20 +1100
Subject: [PATCH] Improve error message for missing content model on import

I was initially going to refactor out the error message into Import.php,
but it quickly became apparent that WikiImporter's error handling needs a
LOT of work. In particular, to localise the error message into the user's
language is sadly non-trivial.

Although not used currently, the MWUnknownContentModelException subclass
will help with error handling improvements in the future.

Bug: T49270
Change-Id: I9f53c9d6a8a2ea842cb2ba94d4131e10a8b08f5d
---
 autoload.php                        |  1 +
 includes/content/ContentHandler.php | 31 +++++++++++++++++++++++++++--
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/autoload.php b/autoload.php
index a2f432f6fd..caad45f4a8 100644
--- a/autoload.php
+++ b/autoload.php
@@ -728,6 +728,7 @@ $wgAutoloadLocalClasses = array(
 	'MWSaltedPassword' => __DIR__ . '/includes/password/MWSaltedPassword.php',
 	'MWTidy' => __DIR__ . '/includes/parser/MWTidy.php',
 	'MWTimestamp' => __DIR__ . '/includes/MWTimestamp.php',
+	'MWUnknownContentModelException' => __DIR__ . '/includes/content/ContentHandler.php',
 	'MachineReadableRCFeedFormatter' => __DIR__ . '/includes/rcfeed/MachineReadableRCFeedFormatter.php',
 	'MagicWord' => __DIR__ . '/includes/MagicWord.php',
 	'MagicWordArray' => __DIR__ . '/includes/MagicWord.php',
diff --git a/includes/content/ContentHandler.php b/includes/content/ContentHandler.php
index 76f2a7b8d9..acaa288f43 100644
--- a/includes/content/ContentHandler.php
+++ b/includes/content/ContentHandler.php
@@ -33,6 +33,32 @@
 class MWContentSerializationException extends MWException {
 }
 
+/**
+ * Exception thrown when an unregistered content model is requested. This error
+ * can be triggered by user input, so a separate exception class is provided so
+ * callers can substitute a context-specific, internationalised error message.
+ *
+ * @ingroup Content
+ * @since 1.27
+ */
+class MWUnknownContentModelException extends MWException {
+	/** @var string The name of the unknown content model */
+	private $modelId;
+
+	/** @param string $modelId */
+	function __construct( $modelId ) {
+		parent::__construct( "The content model '$modelId' is not registered on this wiki.\n" .
+			'See https://www.mediawiki.org/wiki/Content_handlers to find out which extensions ' .
+			'handle this content model.' );
+		$this->modelId = $modelId;
+	}
+
+	/** @return string */
+	public function getModelId() {
+		return $modelId;
+	}
+}
+
 /**
  * A content handler knows how do deal with a specific type of content on a wiki
  * page. Content is stored in the database in a serialized form (using a
@@ -307,7 +333,8 @@ abstract class ContentHandler {
 	 * @param string $modelId The ID of the content model for which to get a
 	 *    handler. Use CONTENT_MODEL_XXX constants.
 	 *
-	 * @throws MWException If no handler is known for the model ID.
+	 * @throws MWException For internal errors and problems in the configuration.
+	 * @throws MWUnknownContentModelException If no handler is known for the model ID.
 	 * @return ContentHandler The ContentHandler singleton for handling the model given by the ID.
 	 */
 	public static function getForModelID( $modelId ) {
@@ -323,7 +350,7 @@ abstract class ContentHandler {
 			Hooks::run( 'ContentHandlerForModelID', array( $modelId, &$handler ) );
 
 			if ( $handler === null ) {
-				throw new MWException( "No handler for model '$modelId' registered in \$wgContentHandlers" );
+				throw new MWUnknownContentModelException( $modelId );
 			}
 
 			if ( !( $handler instanceof ContentHandler ) ) {
-- 
2.20.1