Function Reference/add action

来自WordPress中文文档
跳转至: 导航搜索

wordpress.org.cn

Description

Hooks a function on to a specific action.

See Plugin API/Action Reference for a list of action hooks. Actions are (usually) triggered when the WordPress core calls do_action().

Usage

%%%add_action( $tag, $function_to_add, $priority, $accepted_args );%%%

Parameters

tt$tag/tt
(string) (required) The name of the action to which $function_to_add is hooked. (See Plugin API/Action Reference for a list of action hooks). Can also be the name of an action inside a theme or plugin file, or the special tag "all", in which case the function will be called for all hooks.
Default: Nonenoinclude

div class=template-description style=padding: 0 1.5em; border: 1px solid #eeeeee; background-color: #f9f9f9

Notes

This template is for standardizing how parameters look in the Function Reference and in Template Tags. Here is an example of this template being called: prenowiki检查到模板循环:模板:Parameter/nowiki/pre 检查到模板循环:模板:Parameter

The usage of this template is below: prenowiki检查到模板循环:模板:Parameter/nowiki/pre Let's take a closer look at the parameters..

name
The name of the parameter.
datatype
The datatype that should be given for this parameter when called.
  • string
  • integer
  • boolean
  • mixed
description
A short description of the parameter.
importance
Set this parameter to optional if the parameter is optional. Otherwise, do not declare this parameter—it defaults to required.
  • required
  • optional
default
If this parameter is optional, ttdefault/tt is the value that will be used if the parameter is not declared.

wordpress.org.cn /div /noinclude

tt$function_to_add/tt
(callback) (required) The name of the function you wish to be hooked. Note: Only string-formatted syntaxes listed in the PHP documentation for the 'callback' type are valid.
Default: Nonenoinclude

div class=template-description style=padding: 0 1.5em; border: 1px solid #eeeeee; background-color: #f9f9f9

Notes

This template is for standardizing how parameters look in the Function Reference and in Template Tags. Here is an example of this template being called: prenowiki检查到模板循环:模板:Parameter/nowiki/pre 检查到模板循环:模板:Parameter

The usage of this template is below: prenowiki检查到模板循环:模板:Parameter/nowiki/pre Let's take a closer look at the parameters..

name
The name of the parameter.
datatype
The datatype that should be given for this parameter when called.
  • string
  • integer
  • boolean
  • mixed
description
A short description of the parameter.
importance
Set this parameter to optional if the parameter is optional. Otherwise, do not declare this parameter—it defaults to required.
  • required
  • optional
default
If this parameter is optional, ttdefault/tt is the value that will be used if the parameter is not declared.

wordpress.org.cn /div /noinclude

tt$priority/tt
(int) (optional) Used to specify the order in which the functions associated with a particular action are executed. Lower numbers correspond with earlier execution, and functions with the same priority are executed in the order in which they were added to the action.
Default: 10noinclude

div class=template-description style=padding: 0 1.5em; border: 1px solid #eeeeee; background-color: #f9f9f9

Notes

This template is for standardizing how parameters look in the Function Reference and in Template Tags. Here is an example of this template being called: prenowiki检查到模板循环:模板:Parameter/nowiki/pre 检查到模板循环:模板:Parameter

The usage of this template is below: prenowiki检查到模板循环:模板:Parameter/nowiki/pre Let's take a closer look at the parameters..

name
The name of the parameter.
datatype
The datatype that should be given for this parameter when called.
  • string
  • integer
  • boolean
  • mixed
description
A short description of the parameter.
importance
Set this parameter to optional if the parameter is optional. Otherwise, do not declare this parameter—it defaults to required.
  • required
  • optional
default
If this parameter is optional, ttdefault/tt is the value that will be used if the parameter is not declared.

wordpress.org.cn /div /noinclude

tt$accepted_args/tt
(int) (optional) The number of arguments the hooked function accepts. In WordPress 1.5.1+, hooked functions can take extra arguments that are set when the matching do_action() or apply_filters() call is run. For example, the action comment_id_not_found will pass any functions that hook onto it the ID of the requested comment.
Default: 1noinclude

div class=template-description style=padding: 0 1.5em; border: 1px solid #eeeeee; background-color: #f9f9f9

Notes

This template is for standardizing how parameters look in the Function Reference and in Template Tags. Here is an example of this template being called: prenowiki检查到模板循环:模板:Parameter/nowiki/pre 检查到模板循环:模板:Parameter

The usage of this template is below: prenowiki检查到模板循环:模板:Parameter/nowiki/pre Let's take a closer look at the parameters..

name
The name of the parameter.
datatype
The datatype that should be given for this parameter when called.
  • string
  • integer
  • boolean
  • mixed
description
A short description of the parameter.
importance
Set this parameter to optional if the parameter is optional. Otherwise, do not declare this parameter—it defaults to required.
  • required
  • optional
default
If this parameter is optional, ttdefault/tt is the value that will be used if the parameter is not declared.

wordpress.org.cn /div /noinclude

Return Values

(boolean) 
Always True.

Examples

Simple Hook

To email some friends whenever an entry is posted on your blog:

function email_friends( $post_ID )  
{
   $friends = 'bob@example.org, susie@example.org';
   wp_mail( $friends, "sally's blog updated", 'I just put something on my blog: http://blog.example.com' );

   return $post_ID;
}
add_action( 'publish_post', 'email_friends' );

Accepted Arguments

A hooked function can optionally accept arguments from the action call, if any are set to be passed. In this simplistic example, the echo_comment_id function takes the $comment_id argument, which is automatically passed to when the do_action() call using the comment_id_not_found filter hook is run.

function echo_comment_id( $comment_id ) 
{
   echo 'Comment ID ' . $comment_id . ' could not be found';
}
add_action( 'comment_id_not_found', 'echo_comment_id', 10, 1 );

Notes

To find out the number and name of arguments for an action, simply search the code base for the matching do_action() call. For example, if you are hooking into 'save_post', you would find it in post.php: %%% <?php do_action( 'save_post', $post_ID, $post ); ?> %%%

Your add_action call would look like: %%% <?php add_action( 'save_post', 'my_save_post', 10, 2 ); ?> %%%

And your function would be:

function my_save_post( $post_ID, $post )
{
   // do stuff here
}

Using add_action with a class

To use the add_action hook when your plugin or theme is built up using classes, add $this to your add_action call together with the function name within that class, like so:

class MyPluginClass
{
    public function __construct()
    {
         //add your actions to the constructor!
         add_action( 'save_post', array( $this, 'myplugin_save_posts' ) );
    }
    
    public function myplugin_save_posts()
    {
         //do stuff here...
    }
}

Change Log

Since 1.2.0

Source File

add_action() is located in onlyincludecodewp-includes/plugin.php/code/onlyinclude

div class=template-description style=padding: 0 1.5em; border: 1px solid #eeeeee; background-color: #f9f9f9

Template Description

Link to the source code on http://core.trac.wordpress.org/browser/.

Parameters

  1. filename
  2. (option) path to codetag/code (version) or codetrunk/code. This option is only used for a new function.br /Default: codetrunk/code -- trunk is the latest bleeding edge development version of WordPress.

Usage

Link to the stable version: pre检查到模板循环:模板:Trac/pre

Link to trunk: pre检查到模板循环:模板:Trac/pre

/div

wordpress.org.cn.

Related

Actions: has_action, add_action, do_action, do_action_ref_array, did_action, remove_action, remove_all_actions

includeonlydiv style=clear:both; background-color:#F7F7F7; border:1px solid #CCCCCC; color:#000000; padding:7px; margin:0.5em auto 0.5em auto; vertical-align:middle;See also index of Function Reference and index of Template Tags./div/includeonlynoinclude

Description

This Template is used by Codex:Template Messages.

Usage

pre 检查到模板循环:模板:Message /pre

Result

检查到模板循环:模板:Message

/noinclude

includeonlydiv style=clear:both; background-color:#EEEEFF; border:1px solid #CCCCCC; color:#000000; padding:7px; margin:0.5em auto 0.5em auto; vertical-align:middle;This article is marked as in need of editing. You can help Codex by editing it./div/includeonlynoinclude

Description

This Template is used by Codex:Template Messages.

Usage

pre 检查到模板循环:模板:Message /pre

Result

检查到模板循环:模板:Message

/noinclude