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Introduction to TYPOlight

If we simplify things, TYPOlight is basically structured as follows:

Config File Config file that specifies the hierarchy of data structure and thereby which datacontainer to load for which view, e.g. tl_mytable e.g. system/modules/_<mymodule>_/config/config.php
Data Container Array (DCA) An array structure that defines to TL's Backend Class, how to display the data obtained from the DataContainer library (see below) to the user. The DCA has parameters to control the config, listing, operations, edit palettes (and sub-palettes), fields and their evaluation and formatting e.g. system/modules/_<mymodule>_/dca/tl_mytable.php
Data Container A library that provides an interface (edit, list, cut, copy, paste, etc.) with a specific type of stored data, e.g. filesystem, database or other custom data e.g. /system/drivers/DC_Table.php
Front-end Modules A set of classes that retrieve data directly from the database and may then load the DCA dynamically to know how to format the data for the front-end to match that of the back-end, although this is optional e.g. system/modules/_<mymodule>_/ModuleMyModule.php

Its therefore important to understand the difference between the Data Container (e.g. DC_Table.php) and the Data Container Array (DCA, e.g. dca/tl_news.php). This understanding will greatly improve your ability to develop for TYPOlight.

Config files and Data Container Array (DCA) files

In order to practise your understanding of the config files, the DCA (Data Container Array) and its implementation to create a Back-End Module and Front-End Module, you can follow the Tutorial example of a CD Catalog:

  • Extension Tutorial - will show you how to develop your own custom CD catalog application

Also, to understand the various parts of the DCA, you can read through its documentation:

The Data Container

The data container is used almost everywhere in the TYPOlight backend. There are three data containers included with TYPOlight, although you are of course free to create/write your own Data Containers and provide them as the dataContainer of your Data Container Array (DCA).

As above, Data Containers are located in system/drivers/ directory, and must start with a name DC_. Most commonly used one is of course the DC_Table, which provides a very elegant mechanism to list, edit and save database table information. Here's a short description of the data containers included in TYPOlight core:

Table Default data container, provides access to a database system.
File This is the data container for localconfig.php, where the system settings are stored.
Folder Data container "Folder" provides directory access like the file manager

Callbacks and the Data Container

The data container is often passed to a callback in backend, e.g.

  • onload_callback, ondelete_callback
  • options_callback, input_field_callback, load_callback, save_callback

Here are the variables you have access to from the passed DataContainer $dc variable in your callback function, where $dc would be your Data Container object. Please note that this is only related/tested with DC_Table.

$dc->id int The id of the affected table row.
$dc->table string The table this data container is working on. This could be tl_settings for a File data container, it does not have to be a database table!
$dc->value mixed Value of the current field
$dc->field string Name of the current field
$dc->inputName string Name attribute of the current input field
$dc->palette string Name of the current palette
$dc->parentTable string Name of the parent table Applies to DC_Table only.
$dc->childTabe array Names of one or more child tables Applies to DC_Table only.
$dc->rootIds mixed IDs of all root records Can be an array or single value (string). Applies to DC_Table only.

Examples of Callbacks

Here is an example of a config onload_callback using the Data Container to retrieve data based on the current ID, $dc->id:

 1 <?php
 2 
 3 /**
 4 * Update the RSS feed
 5 * @param object
 6  */
 7 public function generateFeed(DataContainer $dc)
 8 {
 9     if (!$dc->id)
10     {
11         return;
12     }
13 
14     $this->import('Calendar');
15     $this->Calendar->generateFeed($dc->id);
16 }
17 
18 ?>

Here is an example of a field save_callback passing the variable value of the current field, and the Data Container. It then processes the variable value and returns the new value to be saved in the database.

 1 <?php
 2 
 3 /**
 4 * Deserialize and store the tags
 5 * @param object
 6 * @param object
 7  */
 8 public function saveTags($varValue, DataContainer $dc)
 9 {
10     $options = deserialize($varValue, true);
11     if (!is_array($options))
12     {
13         return _;
14     }
15 
16     return join(',', $options);
17 
18 }
19 ?>

Debugging the Data Container

While developing applications it may be beneficial to place the following in your code where you need to check the contents of your Data Container:

1 <?php
2 
3 print_r($dc);
4 
5 ?>

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