Drupal的组成部分 1.模块系统（Drupal钩子）

让模块与Drupal核心关联。

Drupal的模块系统基于“钩子” 。钩子是一个PHP函数，名为foo_bar （ ） ，其中“foo"是模块的模块（其文件名这样是foo.module ）同时“ bar ”是钩子的名字。每个钩子的定义参数设置和某一特定结果的类型。

为了扩大Drupal功能，一个模块只需实现一个简单钩子。当Drupal允许能够模块作用，表明哪些模块执行了一个钩子并且调用这个钩子来启用模块。实现现有的钩子宰这儿被解释开发者文档的钩子部分。字符串“hook”是作为模块名称的钩子定义的一个占位符。例如，如果模块文件名为example.module ，然后实现hook_help( )以该模块example_help( )来定义。

函数

名称	位置	描述
custom_url_rewrite_inbound	modules/system/system.api.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	modules/system/system.api.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	modules/node/node.api.php	Define access restrictions.
hook_actions_delete	modules/trigger/trigger.api.php	Execute code after an action is deleted.
hook_action_info	modules/trigger/trigger.api.php	Declare information about one or more Drupal actions.
hook_action_info_alter	modules/trigger/trigger.api.php	Alter the actions declared by another module.
hook_aggregator_fetch	modules/aggregator/aggregator.api.php	Implement this hook to create an alternative fetcher for aggregator module.
hook_aggregator_fetch_info	modules/aggregator/aggregator.api.php	Implement this hook to expose the title and a short description of your fetcher.
hook_aggregator_parse	modules/aggregator/aggregator.api.php	Implement this hook to create an alternative parser for aggregator module.
hook_aggregator_parse_info	modules/aggregator/aggregator.api.php	Implement this hook to expose the title and a short description of your parser.
hook_aggregator_process	modules/aggregator/aggregator.api.php	Implement this hook to create a processor for aggregator module.
hook_aggregator_process_info	modules/aggregator/aggregator.api.php	Implement this hook to expose the title and a short description of your processor.
hook_aggregator_remove	modules/aggregator/aggregator.api.php	Implement this hook to remove stored data if a feed is being deleted or a feed's items are being removed.
hook_block_configure	modules/block/block.api.php	Configuration form for the block.
hook_block_list	modules/block/block.api.php	List of all blocks defined by the module.
hook_block_save	modules/block/block.api.php	Save the configuration options.
hook_block_view	modules/block/block.api.php	Process the block when enabled in a region in order to view its contents.
hook_boot	modules/system/system.api.php	Perform setup tasks. See also, hook_init.
hook_comment_delete	modules/comment/comment.api.php	The comment is being deleted by the moderator.
hook_comment_insert	modules/comment/comment.api.php	The comment is being inserted.
hook_comment_publish	modules/comment/comment.api.php	The comment is being published by the moderator.
hook_comment_unpublish	modules/comment/comment.api.php	The comment is being unpublished by the moderator.
hook_comment_update	modules/comment/comment.api.php	The comment is being updated.
hook_comment_validate	modules/comment/comment.api.php	The user has just finished editing the comment and is trying to preview or submit it. This hook can be used to check or even modify the node. Errors should be set with form_set_error().
hook_comment_view	modules/comment/comment.api.php	The comment is being viewed. This hook can be used to add additional data to the comment before theming.
hook_cron	modules/system/system.api.php	Perform periodic actions.
hook_db_rewrite_sql	modules/system/system.api.php	Rewrite database queries, usually for access control.
hook_delete	modules/node/node.api.php	Respond to node deletion.
hook_disable	modules/system/system.api.php	Perform necessary actions before module is disabled.
hook_elements	modules/system/system.api.php	Allows modules to declare their own Forms API element types and specify their default values.
hook_enable	modules/system/system.api.php	Perform necessary actions after module is enabled.
hook_exit	modules/system/system.api.php	Perform cleanup tasks.
hook_file_copy	modules/system/system.api.php	Respond to a file that has been copied.
hook_file_delete	modules/system/system.api.php	Respond to a file being deleted.
hook_file_download	modules/system/system.api.php	Control access to private file downloads and specify HTTP headers.
hook_file_insert	modules/system/system.api.php	Respond to a file being added.
hook_file_load	modules/system/system.api.php	Load additional information into file objects.
hook_file_move	modules/system/system.api.php	Respond to a file that has been moved.
hook_file_references	modules/system/system.api.php	Report the number of times a file is referenced by a module.
hook_file_status	modules/system/system.api.php	Respond to a file that has changed status.
hook_file_update	modules/system/system.api.php	Respond to a file being updated.
hook_file_validate	modules/system/system.api.php	Check that files meet a given criteria.
hook_filter	modules/filter/filter.api.php	Define content filters.
hook_filter_tips	modules/filter/filter.api.php	Provide tips for using filters.
hook_flush_caches	modules/system/system.api.php	Add a list of cache tables to be cleared.
hook_footer	modules/system/system.api.php	Insert closing HTML.
hook_form	modules/node/node.api.php	Display a node editing form.
hook_forms	modules/system/system.api.php	Map form_ids to builder functions.
hook_form_alter	modules/system/system.api.php	Perform alterations before a form is rendered.
hook_form_FORM_ID_alter	modules/system/system.api.php	Provide a form-specific alteration instead of the global hook_form_alter().
hook_help	modules/help/help.api.php	Provide online user help.
hook_hook_info	modules/trigger/trigger.api.php	Expose a list of triggers (events) that your module is allowing users to assign actions to.
hook_image_toolkits	modules/system/system.api.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	modules/system/system.api.php	Perform setup tasks. See also, hook_boot.
hook_insert	modules/node/node.api.php	Respond to node insertion.
hook_install	modules/system/system.api.php	Install the current version of the database schema, and any other setup tasks.
hook_js_alter	modules/system/system.api.php	Perform necessary alterations to the JavaScript before it is presented on the page.
hook_link	modules/system/system.api.php	Define internal Drupal links.
hook_link_alter	modules/system/system.api.php	Perform alterations before links on a comment are rendered. One popular use of this hook is to add/delete links from other modules.
hook_load	modules/node/node.api.php	Load node-type-specific information.
hook_locale	modules/locale/locale.api.php	Allows modules to define their own text groups that can be translated.
hook_mail	modules/system/system.api.php	Prepare a message based on parameters. @see drupal_mail for more.
hook_mail_alter	modules/system/system.api.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	modules/menu/menu.api.php	Define menu items and page callbacks.
hook_menu_alter	modules/menu/menu.api.php	Alter the data being saved to the {menu_router} table after hook_menu is invoked.
hook_menu_link_alter	modules/menu/menu.api.php	Alter the data being saved to the {menu_links} table bymenu_link_save().
hook_modules_disabled	modules/system/system.api.php	Perform necessary actions after modules are disabled.
hook_modules_enabled	modules/system/system.api.php	Perform necessary actions after modules are enabled.
hook_modules_installed	modules/system/system.api.php	Perform necessary actions after modules are installed.
hook_modules_uninstalled	modules/system/system.api.php	Perform necessary actions after modules are uninstalled.
hook_nodeapi_alter	modules/node/node.api.php	Fiter, substitute or otherwise alter the $node's raw text.
hook_nodeapi_delete	modules/node/node.api.php	Act on node deletion.
hook_nodeapi_delete_revision	modules/node/node.api.php	A revision of the node is deleted.
hook_nodeapi_insert	modules/node/node.api.php	The node being created (inserted in the database).
hook_nodeapi_load	modules/node/node.api.php	Act on node objects when loaded.
hook_nodeapi_prepare	modules/node/node.api.php	The node is about to be shown on the add/edit form.
hook_nodeapi_prepare_translation	modules/node/node.api.php	The node is being cloned for translation.
hook_nodeapi_presave	modules/node/node.api.php	The node passed validation and is about to be saved.
hook_nodeapi_rss_item	modules/node/node.api.php	An RSS feed is being generated.
hook_nodeapi_search_result	modules/node/node.api.php	The node is being displayed as a search result.
hook_nodeapi_update	modules/node/node.api.php	The node being updated.
hook_nodeapi_update_index	modules/node/node.api.php	The node is being indexed.
hook_nodeapi_validate	modules/node/node.api.php	The user has finished editing the node and is previewing or submitting it.
hook_nodeapi_view	modules/node/node.api.php	The node content is being assembled before rendering.
hook_node_access_records	modules/node/node.api.php	Set permissions for a node to be written to the database.
hook_node_grants	modules/node/node.api.php	Inform the node access system what permissions the user has.
hook_node_info	modules/node/node.api.php	Define module-provided node types.
hook_node_operations	modules/node/node.api.php	Add mass node operations.
hook_node_type	modules/node/node.api.php	Act on node type changes.
hook_perm	modules/system/system.api.php	Define user permissions.
hook_prepare	modules/node/node.api.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	modules/system/system.api.php	Perform alterations profile items before they are rendered. You may omit/add/re-sort/re-categorize, etc.
hook_query_alter	modules/system/system.api.php	Perform alterations to a structured query.
hook_query_TAG_alter	modules/system/system.api.php	Perform alterations to a structured query for a given tag. See alsohook_query_alter()
hook_requirements	modules/system/system.api.php	Check installation requirements and do status reporting.
hook_schema	modules/system/system.api.php	Define the current version of the database schema.
hook_schema_alter	modules/system/system.api.php	Perform alterations to existing database schemas.
hook_search	modules/search/search.api.php	Define a custom search routine.
hook_search_preprocess	modules/search/search.api.php	Preprocess text for the search index.
hook_system_info_alter	modules/system/system.api.php	Alter the information parsed from module and theme .info files
hook_taxonomy_term_delete	modules/taxonomy/taxonomy.api.php	Respond to the deletion of taxonomy terms.
hook_taxonomy_term_insert	modules/taxonomy/taxonomy.api.php	Act on taxonomy terms when inserted.
hook_taxonomy_term_load	modules/taxonomy/taxonomy.api.php	Act on taxonomy terms when loaded.
hook_taxonomy_term_update	modules/taxonomy/taxonomy.api.php	Act on taxonomy terms when updated.
hook_taxonomy_vocabulary_delete	modules/taxonomy/taxonomy.api.php	Respond to the deletion of taxonomy vocabularies.
hook_taxonomy_vocabulary_insert	modules/taxonomy/taxonomy.api.php	Act on taxonomy vocabularies when inserted.
hook_taxonomy_vocabulary_load	modules/taxonomy/taxonomy.api.php	Act on taxonomy vocabularies when loaded.
hook_taxonomy_vocabulary_update	modules/taxonomy/taxonomy.api.php	Act on taxonomy vocabularies when updated.
hook_theme	modules/system/system.api.php	Register a module (or theme's) theme implementations.
hook_theme_registry_alter	modules/system/system.api.php	Alter the theme registry information returned fromhook_theme().
hook_translated_menu_link_alter	modules/menu/menu.api.php	Alter a menu link after it's translated, but before it's rendered.
hook_translation_link_alter	modules/locale/locale.api.php	Perform alterations on translation links.
hook_uninstall	modules/system/system.api.php	Remove any information that the module sets.
hook_update	modules/node/node.api.php	Respond to node updating.
hook_update_index	modules/search/search.api.php	Update Drupal's full-text index for this module.
hook_update_N	modules/system/system.api.php	Perform a single update. For each patch which requires a database change add a newhook_update_N() which will be called by update.php.
hook_update_status_alter	modules/update/update.api.php	Alter the information about available updates for projects.
hook_user	modules/user/user.api.php	Act on user account actions.
hook_user_cancel	modules/user/user.api.php	Act on user account cancellations.
hook_user_cancel_methods_alter	modules/user/user.api.php	Modify account cancellation methods.
hook_user_operations	modules/user/user.api.php	Add mass user operations.
hook_validate	modules/node/node.api.php	Verify a node editing form.
hook_view	modules/node/node.api.php	Display a node.
hook_watchdog	modules/system/system.api.php	Log an event message
hook_xmlrpc	modules/system/system.api.php	Register XML-RPC callbacks.
module_hook	includes/module.inc	Determine whether a module implements a hook.
module_implements	includes/module.inc	Determine which modules are implementing a hook.
module_invoke	includes/module.inc	Invoke a hook in a particular module.
module_invoke_all	includes/module.inc	Invoke a hook in all enabled modules that implement it.
_module_implements_maintenance	includes/module.inc	This is the maintenance version of module_implements for internal use only.

补充：

钩子可以认为是Drupal的内部事件。他们也被称为回调，但是他们是通过函数命名约定构建的，而不是通过注册监听器，他们不是真正的回调。钩子允许模块“注入”到Drupal的执行进程中。

假设一个用户登录到你的Drupal网站。当用户登录时，Drupal的会触发hook_user_login（）钩子。这意味着任何按照“模块名称+钩子名称”约定命名的函数将被调用。例如：评论(comment)模块的comment_user_login ，本地化（locale ）模块的locale_user_login（），节点(node)模块的node_user_login（），以及其他任何类似名称的函数都将被调用。如果你要编写一个定制的模块，名为spammy.module和包含一个函数叫做spammy_user_login（），它发送了一封邮件给用户，将你的函数也会被调用。那么，倒霉的用户每次登录都将收到不请自来的电子邮件。

最常见的方式是，在模块中实现这些钩子以注入到Drupal的核心中。