Back End Modules

A back end module in Contao is essentially a new back end navigation entry. So by default, Contao ships with a few back end modules pre-installed:

  • Content
    • Articles
    • Form generator
  • Layout
    • Themes
    • Site structure
  • […]

The first level (“Content” and “Layout” in that example) represent what we call “categories”. The second level are the back end modules.

Historically, back end modules have always existed in Contao so registering a new one is done by extending the $GLOBALS['BE_MOD'] array:

// contao/config/config.php
$GLOBALS['BE_MOD']['content']['my_module'] = [
    'tables' => ['tl_my_module'],
];

As you can see, we’re extending the content category by a new module called my_module. Adding the translation for your new my_module is as simple as having a modules.xlf file at Resources/contao/languages/<ISO-language-key>/modules.xlf:

<?xml version="1.0" encoding="UTF-8"?>
<xliff version="1.1">
  <file datatype="php" original="src/Resources/contao/languages/en/modules.php" source-language="en">
    <body>
      <trans-unit id="MOD.my_module.0">
        <source>My Module</source>
      </trans-unit>
      <trans-unit id="MOD.my_module.1">
        <source>Manage entries of my module</source>
      </trans-unit>
    </body>
  </file>
</xliff>

The $GLOBALS['BE_MOD'] array takes a few different keys. Here’s a list of all the supported keys in no particular order:

  • tables
  • stylesheet
  • javascript
  • callback
  • disablePermissionChecks
  • hideInNavigation
  • <custom-key>

The first key we’re going to learn more about and which is likely also the most important one, is the tables key. The back end of Contao is mainly designed to work on top of database tables although that’s not required. Basically, in our my_module example we’ve configured only one table called tl_my_module. So when the user clicks on our newly created back end navigation module My Module, Contao loads the DCA file of tl_my_module. Depending on the DCA you can determine what happens from then on. Checkout the DCA documentation and the DCA reference for more information.

The tables key takes an array because if that module manages multiple tables (so if your tl_my_module table e.g. had child table definitions), they all have to be listed here.

Both, the stylesheet and javascript keys allow you to load additional CSS and/or JavaScript files whenever the user works within the context of that back end module. Use them as follows:

// contao/config/config.php
$GLOBALS['BE_MOD']['content']['my_module'] = [
    'tables' => ['tl_my_module'],
    'javascript' => ['bundles/mymodule/scripts.js'],
    'stylesheet' => ['bundles/mymodule/styles.css'],
];

The callback key allows you to render whatever content you would like into the content window. It’s a simple class that expects to have a public function generate() that’s then called like so:

// contao/config/config.php
$GLOBALS['BE_MOD']['content']['my_module'] = [
    'callback' => 'MyVendor/MyModule/MyClass'
];

// src/MyClass.php
namespace MyVendor/MyModule;

class MyClass
{
    public function generate()
    {
        return 'string content';
    }
}

This is a very simple, old and thus not very flexible way of specifying your own output. If you would like to use Dependency Injection etc. you’re likely better off using Custom back end routes.

Both, the disablePermissionChecks and the hideInNavigation just take a boolean value. By default they are both set to false which means, permission checks are always executed and the module is always shown in the navigation. The permission check is referring to the user permission settings where you can restrict the access to certain modules for certain users or user groups. However, if you set disablePermissionChecks to true, that module cannot be selected in the permission settings and the checks are not executed. The Contao core uses this feature for example for the undo module as every user has access to their own undo view. The hideInNavigation may be useful if you want to develop a back end module but link to it from anywhere else but the main back end navigation.

The <custom-key> may be used for any custom callback you want to have executed when the user requests a certain action. Requesting a certain action is done by having &key=foobar in the query parameters. As an example you might want to checkout the theme export functionality the Contao core provides. Every single theme gets an export operation which is specified in the respective DCA file tl_theme as follows:

// contao/dca/tl_theme.php
$GLOBALS['TL_DCA']['tl_theme']['list']['operations']['exportTheme'] = [
    'href' => 'key=exportTheme',
    [...]
];

As you can see, we’re specifying key=exportTheme in the href section which will generate something like contao?do=themes&key=exportTheme&id=1... for the theme with database ID 1. When the user now clicks on that link, Contao searches for the key exportTheme in the back end module definition of themes and execute this callback. The corresponding back end module definition thus looks like this:

// contao/config/config.php
$GLOBALS['BE_MOD']['content']['themes'] = [
    'exportTheme' => ['Contao\Theme', 'exportTheme'],
];

You don’t have to specify a class name, you can also specify a service ID as the first array element.