Callbacks are entry-points for custom code in the DCA. Using callbacks you can modify static Data Container Array during runtime.
Callback functions are based on the event dispatcher pattern. You can register one or more callbacks for a certain event and when the event is triggered, the callback functions are being executed.
Callbacks are very similar to Hooks, but always bound to a specific DCA table.
Since Contao 3.2.0, you can also use anonymous functions for DCA callbacks.
|onload_callback||Is executed when the DataContainer object is initialized. Allows you to e.g. check permissions or to modify the Data Container Array dynamically at runtime.|
|oncreate_callback||Is executed when a new record is created.|
|onsubmit_callback||Is executed when a back end form is submitted. Allows you to e.g. modify the form data before it is written to the database (used to calculate intervals in the calendar extension).|
|ondelete_callback||Is executed before a record is removed from the database.|
|oncut_callback||Is executed after a record has been moved to a new position.|
|oncopy_callback||Is executed after a record has been duplicated.|
|oncreate_version_callback||Is executed after the old version of the record has been added to
|onrestore_version_callback||Is executed after a record has been restored from an old version.|
|paste_button_callback||Allows for individual paste buttons and is e.g. used in the site structure to disable buttons depending on the user's permissions (requires an additional command check via load_callback).|
|child_record_callback||Defines how child elements are rendered in "parent view".|
|group_callback||Allows for individual group headers in the listing.|
|label_callback||Allows for individual labels in the listing and is e.g. used in the user module to add status icons.|
|header_callback||Allows for individual labels in header of "parent view".|
|button_callback||Allows for individual navigation icons and is e.g. used in the site structure to disable buttons depending on the user's permissions (requires an additional command check via load_callback).|
|options_callback||Allows you to define an individual function to load data into a drop-down menu or checkbox list. Useful e.g. for conditional foreinKey-relations.|
|input_field_callback||Allows for the creation of individual form fields and is e.g. used in the back end module "personal data" to generate the "purge data" widget. Attention: the field is not saved automatically!|
|load_callback||Is executed when a form field is initialized and can e.g. be used to load a default value.|
|save_callback||Is executed when a field is submitted and can e.g. be used to add an individual validation routine.|