{"id":450,"date":"2014-06-27T11:58:22","date_gmt":"2014-06-27T09:58:22","guid":{"rendered":"http:\/\/self.mestrona.net\/blog\/?p=450"},"modified":"2014-08-03T18:38:26","modified_gmt":"2014-08-03T16:38:26","slug":"rewrite-classes-in-contao","status":"publish","type":"post","link":"https:\/\/s3lf.de\/blog\/2014\/rewrite-classes-in-contao\/","title":{"rendered":"Rewrite Classes in Contao"},"content":{"rendered":"

The Contao Web CMS System<\/a>\u00a0provides the possibility to rewrite classes of the core or of 3rd party modules.<\/p>\n

In case you want to publish your extension, this is not a suggested way because this can create conflicts if two installed modules try to rewrite the same class. But for local modules this is a valid method.<\/p>\n

First of all you must ensure, that your module is loaded after the module you want to rewrite. You can assure this by giving your module a name which comes alphabetically after the name of the module to be rewritten. Or you can add a line<\/p>\n

requires<\/span>[] = \"dlh_googlemaps\"\r\n<\/span><\/pre>\n
to your autoload.ini. Digging into the code you find out that this require statement is\u00a0evaluated in\u00a0\\Contao\\ModuleLoader::scanAndResolve<\/code>.<\/p>\n
Now you simply have to add your class to the autoload.php<\/code>\u00a0with the same class name (without namespace prefix) as the class to be rewritten:<\/p>\n
ClassLoader::addClasses<\/span>(array\r\n<\/span>(\r\n\t'Mymodule\\Googlemap' <\/span>=> 'system\/modules\/mymodule\/classes\/Googlemap.php'<\/span>,\r\n));<\/pre>\n
The class loader uses the class_alias()\u00a0<\/em>PHP function to define an alias for\u00a0the class name without the namespace. So now the class can be instantiated using \\Googlemap<\/code>.<\/p>\n
Your Googlemap.php<\/code> would look like this<\/p>\n
namespace <\/span>Mymodule;\r\n\r\nclass <\/span>Googlemap extends <\/span>\\delahaye\\googlemaps\\Googlemap {\r\n    public static function <\/span>getMapData($intMap<\/span>, $strFormat<\/span>= ''<\/span>, $arrParams<\/span>=false<\/span>) {\r\n        parent<\/span>::getMapData<\/span>($intMap<\/span>, $strFormat<\/span>, $arrParams<\/span>);\r\n        \/\/ your code\r\n    }\r\n}<\/pre>\n
If you set<\/p>\n
$GLOBALS<\/span>['TL_CONFIG'<\/span>]['debugMode'<\/span>] = true<\/span>;\r\n<\/pre>\n
in your localconfig.php<\/code>, a debug area is displayed on the page’s bottom indicating\u00a0which classes are aliased:<\/p>\n
\u00a0\"Screenshot_Selection_006\"<\/p>\n
The method\u00a0\\Contao\\ClassLoader::findClass()<\/code>\u00a0is responsible for searching the registered namespaces for the class. The static field ClassLoader::$namespaces<\/code>\u00a0contains the registered namespaces in reverse order of the loading order of the modules so the first match is picked.<\/p>\n
There is one catch: if two or more of your modules use the same namespace, all of them have to be loaded before the module you want to overwrite (using the required-configuration mentioned above) . Otherwise the namespace will be listed in the wrong order as each namespace can be only registered once and the overwrite will not have an effect.<\/p>\n
References:<\/p>\n