Inside TYPO3

3.5.1. Backend Module API

$TBE_MODULES

In TYPO3 all modules are configured in the global variable, $TBE_MODULES (see t3lib/stddb/tables.php). $TBE_MODULES contains the structure of the backend modules as they are arranged in main- and sub-modules. Every entry in this array represents a menu item on either first level (array key) or second level (value from list) in the left menu in the TYPO3 backend.

 

  $TBE_MODULES = Array (

      'web' => 'list,info,perm,func',

      'file' => 'list',

      'doc' => '',    // This should always be empty!

      'user' => '',

      'tools' => 'em',

      'help' => 'about,cshmanual'

  );

The syntax is:

  $TBE_MODULES[ module ] => "submodule_1,submodule_2,submodule_3,submodule_4"

 

There are two special keys in the $TBE_MODULES array to be aware of:

1. $TBE_MODULES['_PATHS'] is an array used by extensions to register module file locations (for backend modules located in extensions). Obviously, this is not representing a main module.

2. $TBE_MODULES['doc'] is a main module which cannot have any sub modules.

 

Module file locations

Modules can be located in the file system after three different principles:

1. Core modules
   The file location of the core modules is "typo3/mod/". Here you will find a number of folders (main modules) and sub-folders (sub modules) with "conf.php" files and icons in. It's unlikely that new core modules are added since extensions should provide all future modules. You should never add core modules by yourself.
   Core modules are arranged in folders after the schemes "typo3/mod/[module]" and "typo3/mod/[module]/[submodule]".

2. User defined modules (OBSOLETE)
   Modules located in "../typo3conf/" directory after the same principles as core modules (typo3conf/[module key]/[sub-module key]). If a module or sub-module key in $TBE_MODULES is not found in "typo3/mod/" then it is looked for in "../typo3conf/". Module/Sub-module keys of user defined modules should be prefixed with a lowercase "u", eg. "web_uEtest" (located in "typo3conf/web/uEtest/" or "uMaintest" (located in "typo3conf/uMaintest")
   (Deprecated concept; Do not create user defined modules any more! Create modules in extensions instead.)

3. Modules from extensions
   Custom modules supplied from extensions are located somewhere inside the extension file space. The extension adds the module to the system by an API call in the "ext_tables.php" file. The API call will add the module key to the $TBE_MODULES array and set an entry in $TBE_MODULES['_PATH'] pointing to the absolute path for the module.

Parsing $TBE_MODULES

The backend determines if a module is a core/user or extension module by first looking for a path-entry in $TBE_MODULES['_PATHS'] using "[module]_[submodule]"  as key (this is also the "name" of the module). If an entry is found, this location is set as the path. Otherwise "t3lib_loadmodules" will look first for the module in the core location ("typo3/mod/") and if not found, then in "../typo3conf/".

In any case, a module is only detected if a "conf.php" file was found in its filepath! This file contains configuration of the module; The module name, script, access criteria, type etc.

When the backend needs to get a list of available modules for a backend user the class "t3lib_loadmodules" is used. This code snippet does the trick:

      // Backend Modules:

  $loadModules = t3lib_div::makeInstance('t3lib_loadModules');

  $loadModules->load($TBE_MODULES);

  foreach($loadModules->modules as $mainMod => $info)    {

     ...

  }

The array $loadModules->modules contains information about the modules that were accessible; their names, types, sub modules (if any) and the filepath to their scripts (relative to PATH_typo3).

Registering new modules

Adding new modules should be done by extensions. The API is easy; in the "ext_tables.php" file of the extension you simply need to add code like this:

 

For main modules:

  if (TYPO3_MODE=='BE')    {

      t3lib_extMgm::addModule('txtempM1','','',t3lib_extMgm::extPath($_EXTKEY).'mod1/');

  }

"txtempM1" is the module key of the main module created. It could appear like this in the menu:

 

For sub modules:

  if (TYPO3_MODE=='BE')    {

      t3lib_extMgm::addModule('web','txtempM2','',t3lib_extMgm::extPath($_EXTKEY).'mod2/');

  }

"web" is the name of the main module (the "Web>" module) and "txtempM2" is the sub-module key. In the menu this module could appear like this:

 

After such two modules has been added the $TBE_MODULES array could look like this:

 

Notice that "txtempM1" became a key in the array (main modules) and "txtempM2" was added to the list of modules in the "Web" main module (sub-modules are listed). Also notice that the "_PATHS" key contains an array of file locations of all the modules that are coming from extensions! The last two entries in the list defines the locations of the two modules from our example!