Hooks

Allow modules to interact with the Drupal core.

Drupal's module system is based on the concept of "hooks". A hook is a PHP function that is named foo_bar(), where "foo" is the name of the module (whose filename is thus foo.module) and "bar" is the name of the hook. Each hook has a defined set of parameters and a specified result type.

To extend Drupal, a module need simply implement a hook. When Drupal wishes to allow intervention from modules, it determines which modules implement a hook and call that hook in all enabled modules that implement it.

The available hooks to implement are explained here in the Hooks section of the developer documentation. The string "hook" is used as a placeholder for the module name is the hook definitions. For example, if the module file is called example.module, then hook_help() as implemented by that module would be defined as example_help().

File

includes/module.inc, line 103

API for loading and interacting with Drupal modules.

Functions

Name	Location	Description
module_invoke_all	includes/module.inc	Invoke a hook in all enabled modules that implement it.
module_invoke	includes/module.inc	Invoke a hook in a particular module.
module_implements	includes/module.inc	Determine which modules are implementing a hook.
module_hook	includes/module.inc	Determine whether a module implements a hook.
hook_xmlrpc	developer/hooks/core.php	Register XML-RPC callbacks.
hook_view	developer/hooks/node.php	Display a node.
hook_validate	developer/hooks/node.php	Verify a node editing form.
hook_user	developer/hooks/core.php	Act on user account actions.
hook_update_index	developer/hooks/core.php	Update Drupal's full-text index for this module.
hook_update	developer/hooks/node.php	Respond to node updating.
hook_textarea	developer/hooks/core.php	React to textarea additions.
hook_taxonomy	developer/hooks/core.php	Act on taxonomy changes.
hook_settings	developer/hooks/core.php	Declare administrative settings for a module.
hook_search_preprocess	developer/hooks/core.php	Preprocess text for the search index.
hook_search_item	developer/hooks/core.php	Format a search result.
hook_search	developer/hooks/core.php	Define a custom search routine.
hook_ping	developer/hooks/core.php	Ping another server.
hook_perm	developer/hooks/core.php	Define user permissions.
hook_onload	developer/hooks/core.php	Insert a JavaScript onload handler.
hook_node_types	developer/hooks/node.php	Define multiple node types.
hook_node_name	developer/hooks/node.php	Define the human-readable name of a node type.
hook_node_grants	developer/hooks/core.php	Grant access to nodes.
hook_nodeapi	developer/hooks/core.php	Act on nodes defined by other modules.
hook_menu	developer/hooks/core.php	Define menu items and page callbacks.
hook_load	developer/hooks/node.php	Load node-type-specific information.
hook_link	developer/hooks/core.php	Define internal Drupal links.
hook_insert	developer/hooks/node.php	Respond to node insertion.
hook_init	developer/hooks/core.php	Perform setup tasks.
hook_info	developer/hooks/authentication.php	Declare authentication scheme information.
hook_help	developer/hooks/core.php	Provide online user help.
hook_form	developer/hooks/node.php	Display a node editing form.
hook_footer	developer/hooks/core.php	Insert closing HTML.
hook_filter_tips	developer/hooks/core.php	Provide tips for using filters.
hook_filter	developer/hooks/core.php	Define content filters.
hook_exit	developer/hooks/core.php	Perform cleanup tasks.
hook_delete	developer/hooks/node.php	Respond to node deletion.
hook_db_rewrite_sql	developer/hooks/core.php	Add JOIN and WHERE statements to queries and decide whether the primary_field shall be made DISTINCT. For node objects, primary field is always called nid. For taxonomy terms, it is tid and for vocabularies it is vid. For comments, it is cid. Note…
hook_cron	developer/hooks/core.php	Perform periodic actions.
hook_comment	developer/hooks/core.php	Act on comment modification.
hook_block	developer/hooks/core.php	Declare a block or set of blocks.
hook_auth	developer/hooks/authentication.php	Verify authentication of a user.
hook_access	developer/hooks/node.php	Define access restrictions.