api.drupal.org BETA

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().

Functions

Name	Location	Description
custom_url_rewrite_inbound	contributions/docs/developer/hooks/core.php	custom_url_rewrite_inbound is not a hook, it's a function you can add to settings.php to alter incoming requests so they map to a Drupal path. This function is called before modules are loaded and the menu system is initialized and it changes...
custom_url_rewrite_outbound	contributions/docs/developer/hooks/core.php	custom_url_rewrite_outbound is not a hook, it's a function you can add to settings.php to alter all links generated by Drupal. This function is called from url(). This function is called very frequently (100+ times per page) so performance...
hook_access	contributions/docs/developer/hooks/node.php	Define access restrictions.
hook_actions_delete	contributions/docs/developer/hooks/core.php	Execute code after an action is deleted.
hook_action_info	contributions/docs/developer/hooks/core.php	Declare information about one or more Drupal actions.
hook_action_info_alter	contributions/docs/developer/hooks/core.php	Alter the actions declared by another module.
hook_block	contributions/docs/developer/hooks/core.php	Declare a block or set of blocks.
hook_boot	contributions/docs/developer/hooks/core.php	Perform setup tasks. See also, hook_init.
hook_comment	contributions/docs/developer/hooks/core.php	Act on comments.
hook_cron	contributions/docs/developer/hooks/core.php	Perform periodic actions.
hook_db_rewrite_sql	contributions/docs/developer/hooks/core.php	Rewrite database queries, usually for access control.
hook_delete	contributions/docs/developer/hooks/node.php	Respond to node deletion.
hook_disable	contributions/docs/developer/hooks/install.php	Perform necessary actions before module is disabled.
hook_elements	contributions/docs/developer/hooks/core.php	Allows modules to declare their own Forms API element types and specify their default values.
hook_enable	contributions/docs/developer/hooks/install.php	Perform necessary actions after module is enabled.
hook_exit	contributions/docs/developer/hooks/core.php	Perform cleanup tasks.
hook_file_copy	contributions/docs/developer/hooks/file.php	Respond to a file that has been copied.
hook_file_delete	contributions/docs/developer/hooks/file.php	Respond to a file being deleted.
hook_file_download	contributions/docs/developer/hooks/file.php	Control access to private file downloads and specify HTTP headers.
hook_file_insert	contributions/docs/developer/hooks/file.php	Respond to a file being added.
hook_file_load	contributions/docs/developer/hooks/file.php	Load additional information into a file object.
hook_file_move	contributions/docs/developer/hooks/file.php	Respond to a file that has been moved.
hook_file_references	contributions/docs/developer/hooks/file.php	Report the number of times a file is referenced by a module.
hook_file_status	contributions/docs/developer/hooks/file.php	Respond to a file that has changed status.
hook_file_update	contributions/docs/developer/hooks/file.php	Respond to a file being updated.
hook_file_validate	contributions/docs/developer/hooks/file.php	Check that files meet a given criteria.
hook_filter	contributions/docs/developer/hooks/core.php	Define content filters.
hook_filter_tips	contributions/docs/developer/hooks/core.php	Provide tips for using filters.
hook_flush_caches	contributions/docs/developer/hooks/core.php	Add a list of cache tables to be cleared.
hook_footer	contributions/docs/developer/hooks/core.php	Insert closing HTML.
hook_form	contributions/docs/developer/hooks/node.php	Display a node editing form.
hook_forms	contributions/docs/developer/hooks/core.php	Map form_ids to builder functions.
hook_form_alter	contributions/docs/developer/hooks/core.php	Perform alterations before a form is rendered.
hook_form_FORM_ID_alter	contributions/docs/developer/hooks/core.php	Provide a form-specific alteration instead of the global hook_form_alter().
hook_help	contributions/docs/developer/hooks/core.php	Provide online user help.
hook_hook_info	contributions/docs/developer/hooks/core.php	Expose a list of triggers (events) that your module is allowing users to assign actions to.
hook_image_toolkits	contributions/docs/developer/hooks/core.php	Define image toolkits provided by this module. * The file which includes each toolkit's functions must be declared as part of the files array in the module .info file so that the registry will find and parse it. * *
hook_init	contributions/docs/developer/hooks/core.php	Perform setup tasks. See also, hook_boot.
hook_insert	contributions/docs/developer/hooks/node.php	Respond to node insertion.
hook_install	contributions/docs/developer/hooks/install.php	Install the current version of the database schema, and any other setup tasks.
hook_link	contributions/docs/developer/hooks/core.php	Define internal Drupal links.
hook_link_alter	contributions/docs/developer/hooks/core.php	Perform alterations before links on a node are rendered. One popular use of this hook is to add/delete links from other modules.
hook_load	contributions/docs/developer/hooks/node.php	Load node-type-specific information.
hook_locale	contributions/docs/developer/hooks/core.php	Allows modules to define their own text groups that can be translated.
hook_mail	contributions/docs/developer/hooks/core.php	Prepare a message based on parameters. @see drupal_mail for more.
hook_mail_alter	contributions/docs/developer/hooks/core.php	Alter any aspect of the emails sent by Drupal. You can use this hook to add a common site footer to all outgoing emails; add extra header fields and/or modify the mails sent out in any way. HTML-izing the outgoing mails is one possibility. See also...
hook_menu	contributions/docs/developer/hooks/core.php	Define menu items and page callbacks.
hook_menu_alter	contributions/docs/developer/hooks/core.php	Alter the data being saved to the {menu_router} table after hook_menu is invoked.
hook_menu_link_alter	contributions/docs/developer/hooks/core.php	Alter the data being saved to the {menu_links} table by menu_link_save().
hook_modules_disabled	contributions/docs/developer/hooks/core.php	Perform necessary actions after modules are disabled.
hook_modules_enabled	contributions/docs/developer/hooks/core.php	Perform necessary actions after modules are enabled.
hook_modules_installed	contributions/docs/developer/hooks/core.php	Perform necessary actions after modules are installed.
hook_modules_uninstalled	contributions/docs/developer/hooks/core.php	Perform necessary actions after modules are uninstalled.
hook_nodeapi	contributions/docs/developer/hooks/core.php	Act on nodes defined by other modules.
hook_node_access_records	contributions/docs/developer/hooks/core.php	Set permissions for a node to be written to the database.
hook_node_grants	contributions/docs/developer/hooks/core.php	Inform the node access system what permissions the user has.
hook_node_info	contributions/docs/developer/hooks/node.php	Define module-provided node types.
hook_node_operations	contributions/docs/developer/hooks/core.php	Add mass node operations.
hook_node_type	contributions/docs/developer/hooks/node.php	Act on node type changes.
hook_perm	contributions/docs/developer/hooks/core.php	Define user permissions.
hook_ping	contributions/docs/developer/hooks/core.php	Ping another server.
hook_prepare	contributions/docs/developer/hooks/node.php	This is a hook used by node modules. It is called after load but before the node is shown on the add/edit form.
hook_profile_alter	contributions/docs/developer/hooks/core.php	Perform alterations profile items before they are rendered. You may omit/add/re-sort/re-categorize, etc.
hook_requirements	contributions/docs/developer/hooks/install.php	Check installation requirements and do status reporting.
hook_schema	contributions/docs/developer/hooks/install.php	Define the current version of the database schema.
hook_schema_alter	contributions/docs/developer/hooks/core.php	Perform alterations to existing database schemas.
hook_search	contributions/docs/developer/hooks/core.php	Define a custom search routine.
hook_search_preprocess	contributions/docs/developer/hooks/core.php	Preprocess text for the search index.
hook_system_info_alter	contributions/docs/developer/hooks/core.php	Alter the information parsed from module and theme .info files
hook_taxonomy_term_delete	contributions/docs/developer/hooks/core.php	Respond to the deletion of taxonomy terms.
hook_taxonomy_term_insert	contributions/docs/developer/hooks/core.php	Act on taxonomy terms when inserted.
hook_taxonomy_term_load	contributions/docs/developer/hooks/core.php	Act on taxonomy terms when loaded.
hook_taxonomy_term_update	contributions/docs/developer/hooks/core.php	Act on taxonomy terms when updated.
hook_taxonomy_vocabulary_delete	contributions/docs/developer/hooks/core.php	Respond to the deletion of taxonomy vocabularies.
hook_taxonomy_vocabulary_insert	contributions/docs/developer/hooks/core.php	Act on taxonomy vocabularies when inserted.
hook_taxonomy_vocabulary_load	contributions/docs/developer/hooks/core.php	Act on taxonomy vocabularies when loaded.
hook_term_path	contributions/docs/developer/hooks/core.php	Allows modules to provide an alternative path for the terms it manages.
hook_theme	contributions/docs/developer/hooks/core.php	Register a module (or theme's) theme implementations.
hook_theme_registry_alter	contributions/docs/developer/hooks/core.php	Alter the theme registry information returned from hook_theme().
hook_translated_menu_link_alter	contributions/docs/developer/hooks/core.php	Alter a menu link after it's translated, but before it's rendered.
hook_uninstall	contributions/docs/developer/hooks/install.php	Remove any information that the module sets.
hook_update	contributions/docs/developer/hooks/node.php	Respond to node updating.
hook_update_index	contributions/docs/developer/hooks/core.php	Update Drupal's full-text index for this module.
hook_update_N	contributions/docs/developer/hooks/install.php	Perform a single update. For each patch which requires a database change add a new hook_update_N() which will be called by update.php.
hook_update_status_alter	contributions/docs/developer/hooks/core.php	Alter the information about available updates for projects.
hook_user	contributions/docs/developer/hooks/core.php	Act on user account actions.
hook_user_operations	contributions/docs/developer/hooks/core.php	Add mass user operations.
hook_validate	contributions/docs/developer/hooks/node.php	Verify a node editing form.
hook_view	contributions/docs/developer/hooks/node.php	Display a node.
hook_watchdog	contributions/docs/developer/hooks/core.php	Log an event message
hook_xmlrpc	contributions/docs/developer/hooks/core.php	Register XML-RPC callbacks.
module_hook	drupal/includes/module.inc	Determine whether a module implements a hook.
module_implements	drupal/includes/module.inc	Determine which modules are implementing a hook.
module_invoke	drupal/includes/module.inc	Invoke a hook in a particular module.
module_invoke_all	drupal/includes/module.inc	Invoke a hook in all enabled modules that implement it.
_module_implements_maintenance	drupal/includes/module.inc	This is the maintenance version of module_implements for internal use only.