WordPress add a function

add_action( 'save_post', 'wpdocs_my_save_post', 10, 3 );

The name of the action to add the callback to.

add_action( 'save_post', 'wpdocs_my_save_post', 10, 3 );

The callback to be run when the action is called.

add_action( 'save_post', 'wpdocs_my_save_post', 10, 3 );

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:

add_action( 'save_post', 'wpdocs_my_save_post', 10, 3 );

add_action( 'save_post', 'wpdocs_my_save_post', 10, 3 );

The number of arguments the function accepts.

Default:

add_action( 'save_post', 'wpdocs_my_save_post', 10, 3 );

true Always returns true.

add_action( $hook, $function_to_add, $priority, $accepted_args );

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:

do_action( 'save_post', $post_ID, $post, $update );

Your add_action call would look like:

add_action( 'save_post', 'wpdocs_my_save_post', 10, 3 );

And your function would be:

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

File:

add_action( 'save_post', 'wpdocs_my_save_post', 10, 3 );

function add_action( $hook_name, $callback, $priority = 10, $accepted_args = 1 ) {
	return add_filter( $hook_name, $callback, $priority, $accepted_args );
}

1. You must log in to vote on the helpfulness of this noteVote results for this note: 45You must log in to vote on the helpfulness of this note

   Contributed by Codex —

   Using with a Class
   To use

   add_action( 'save_post', 'wpdocs_my_save_post', 10, 3 );

   8 when your plugin or theme is built using classes, you need to use the array callable syntax. You would pass the function to

   add_action( 'save_post', 'wpdocs_my_save_post', 10, 3 );

   8 as an array, with

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

   0 as the first element, then the name of the class method, like so:

   /**
    * Class WP_Docs_Class.
    */
   class WP_Docs_Class {
   
   	/**
   	 * Constructor
   	 */
   	public function __construct() {
   		add_action( 'save_post', array( $this, 'wpdocs_save_posts' ) );
   	}
   
   	/**
   	 * Handle saving post data.
   	 */
   	public function wpdocs_save_posts() {
   		// do stuff here...
   	}
   }
   
   $wpdocsclass = new WP_Docs_Class();

   • Don’t use this in themes you want to distribute. It won’t be possible to remove the action as $this would be a different value; — By theking2 —

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   Contributed by Codex —

   Using with static functions in a class
   If the class is called staticly the approach has to be like below as

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

   0 is not available. This also works if class is extended. Use the following:

   /**
    * Class WP_Docs_Static_Class.
    */
   class WP_Docs_Static_Class {
   
   	/**
   	 * Initializer for setting up action handler
   	 */
   	public static function init() {
   		add_action( 'save_post', array( get_called_class(), 'wpdocs_save_posts' ) );
   	}
   
   	/**
   	 * Handler for saving post data.
   	 */
   	public static function wpdocs_save_posts() {
   		// do stuff here...
   	}
   }
   
   WP_Docs_Static_Class::init();

   • If we have callback function which is static in another class, we can use the following:

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

     2 — By sumeetboga95 —

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   Contributed by Codex —

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

   /**
    * Send email to my friends.
    *
    * @param int $post_id Post ID.
    * @return int Post ID.
    */
   function wpdocs_email_friends( $post_id ) {
   	$friends = '[email protected], [email protected]';
   	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', 'wpdocs_email_friends' );

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   Contributed by mkormendy —

   To pass a variable to the called function of the action, you can use closures (since PHP 5.3+) when the argument is not available in the original coded do_action. For example:

   add_action('wp_footer', function($arguments) use ($myvar) { 
       echo $myvar;
   }, $priority_integer, $accepted_arguments_integer);

   • Don’t use anonymous closures on themes you want to distribute. It would be impossible to remove the action. Instead use closure variables:

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

     3 which can be removed with:

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

     4 with the advantage that typos in the closure name will yeild a helpfull Undfined variable error on typos. — By theking2 —

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   Contributed by Anthony Hortin —

   Related:

   do_action()
   remove_action()

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   Contributed by Lucas Bustamante —

   Passing parameters while using in a Class
   To pass parameters to your method in a Class while calling it with add_action, you can do as following:

   public function __construct() {
       // Actions
       add_action('init', array($this, 'call_somefunction'));
   }
   
   /**
    *    Intermediate function to call add_action with parameters
    */
   public function call_somefunction() {
       $this->somefunction('Hello World');
   }
   
   /**
    *    Actual function that does something
    */
   public function somefunction($text) {
       echo $text;
   }

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   Contributed by Christian Saborio —

   How to add an action that calls a function (with parameters) from an instantiated class:

   do_action( 'save_post', $post_ID, $post, $update );

   0

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   Contributed by Codex —

   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

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

   5 function takes the

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

   6 argument, which is automatically passed to when the

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

   7 call using the

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

   8 filter hook is run.

   do_action( 'save_post', $post_ID, $post, $update );

   1

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   Contributed by theking2 —

   To prevent runtime errors due to easy typo errors (defensive programming) and prevent pollution of the global namespace use closures instead of function names. The sample code adjusted:

   do_action( 'save_post', $post_ID, $post, $update );

   2

   • Do not do this in themes or plugins you intend to distribute, as it will prevent others from removing your callables if desired. — By crstauf —

     How do I add a function to a specific page in WordPress?

     You can use the is_page() conditional tag to target a specific WordPress page to make your changes. You can also use the is_single() tag to target an individual post in the exact same way. You'll do a conditional check for this page (or post if using is_single() instead) by targeting the page ID, title, or slug.

     How to add custom function to functions php in WordPress?

     To add your code to functions. php go to Appearance > Editor then select Theme Functions file and paste your code in the end of editor and click Update File: If there is a syntax error on that code, your site will stop working! Before making changes backup your functions.

     How do I call a custom function in WordPress?

     So effectively:.

     Rename your function to something a bit more unique, like naser_send_notitification().

     Put this code in /wp-content/mu-plugins/custom-funtions.php..

     How do I trigger a function in WordPress?

     You have three options for this:.

     Code the function directly into your theme template file (or another plugin file)..

     Attach it to an action hook..

     Attach it to a filter hook..