Trigger custom action when setting button pressed

1 comment

1. You need a second form with admin_url('admin-post.php') as form action. Then you can hook into admin_post_custom_action to execute your action.

   Sample code:

   add_action( 'admin_post_wpse_79898', 'wpse_79898_test' );
   
   function wpse_79898_test() {
       if ( isset ( $_GET['test'] ) )
           echo esc_html( $_GET['test'] );
   
       die( __FUNCTION__ );
   }
   

   In your settings page:

   <form action="<?php echo admin_url( 'admin-post.php' ); ?>">
   <input type="hidden" name="action" value="wpse_79898">
   <input type="text" name="test" value="">
   <?php submit_button( 'Send' ); ?>
   </form>
   

   ---

   Update

   Here is a rather extended example. It shows:

   • basic security actions (nonces, escaping),
   • how to register and to use the callback,
   • how to redirect back to the original page, this works even for network activated plugins,
   • how to show a custom message based on a white list of allowed values.

   The example I have used here – updating an option – should not be used for plugins activated for on site only. For network activated plugins though this is quite useful, because there is no options API for those.

   I should add comments, but I am too lazy. 🙂 I will write a blog post about this, and update the answer later with a link.

   <?php
   /* Plugin Name: admin-post demo */
   
   add_action( 'wp_loaded', array ( WPSE_79898_Admin_Post_Demo::get_instance(), 'register' ) );
   
   class WPSE_79898_Admin_Post_Demo
   {
       /**
        * Plugin instance.
        *
        * @see get_instance()
        * @type object
        */
       protected static $instance = NULL;
   
       protected $action     = 'wpse_79898';
       protected $option_name     = 'wpse_79898';
       protected $page_id = NULL;
   
       /**
        * Access this plugin’s working instance
        *
        * @wp-hook wp_loaded
        * @return  object of this class
        */
       public static function get_instance()
       {
           NULL === self::$instance and self::$instance = new self;
           return self::$instance;
       }
   
       public function register()
       {
           add_action( 'admin_menu', array ( $this, 'add_menu' ) );
           add_action( "admin_post_$this->action", array ( $this, 'admin_post' ) );
       }
   
       public function add_menu()
       {
           $page_id = add_options_page(
               'Admin Post Demo',
               'Admin Post Demo',
               'manage_options',
               'admin-post-demo',
               array ( $this, 'render_options_page' )
           );
   
           add_action( "load-$page_id", array ( $this, 'parse_message' ) );
       }
   
       public function parse_message()
       {
           if ( ! isset ( $_GET['msg'] ) )
               return;
   
           $text = FALSE;
   
           if ( 'updated' === $_GET['msg'] )
               $this->msg_text = 'Updated!';
   
           if ( 'deleted' === $_GET['msg'] )
               $this->msg_text = 'Deleted!';
   
           if ( $this->msg_text )
               add_action( 'admin_notices', array ( $this, 'render_msg' ) );
       }
   
       public function render_msg()
       {
           echo '<div class="' . esc_attr( $_GET['msg'] ) . '"><p>'
               . $this->msg_text . '</p></div>';
       }
   
       public function render_options_page()
       {
           $option = esc_attr( stripslashes( get_option( $this->option_name ) ) );
           $redirect = urlencode( remove_query_arg( 'msg', $_SERVER['REQUEST_URI'] ) );
           $redirect = urlencode( $_SERVER['REQUEST_URI'] );
   
           ?><h1><?php echo $GLOBALS['title']; ?></h1>
           <form action="<?php echo admin_url( 'admin-post.php' ); ?>" method="POST">
               <input type="hidden" name="action" value="<?php echo $this->action; ?>">
               <?php wp_nonce_field( $this->action, $this->option_name . '_nonce', FALSE ); ?>
               <input type="hidden" name="_wp_http_referer" value="<?php echo $redirect; ?>">
   
               <label for="<?php echo $this->option_name; ?>">Enter some text:</label>
               <input type="text" name="<?php echo $this->option_name;
                   ?>" id="<?php echo $this->option_name;
                   ?>" value="<?php echo $option; ?>">
               <?php submit_button( 'Send' ); ?>
           </form>
           <?php
       }
   
       public function admin_post()
       {
           if ( ! wp_verify_nonce( $_POST[ $this->option_name . '_nonce' ], $this->action ) )
               die( 'Invalid nonce.' . var_export( $_POST, true ) );
   
           if ( isset ( $_POST[ $this->option_name ] ) )
           {
               update_option( $this->option_name, $_POST[ $this->option_name ] );
               $msg = 'updated';
           }
           else
           {
               delete_option( $this->option_name );
               $msg = 'deleted';
           }
   
           if ( ! isset ( $_POST['_wp_http_referer'] ) )
               die( 'Missing target.' );
   
           $url = add_query_arg( 'msg', $msg, urldecode( $_POST['_wp_http_referer'] ) );
   
           wp_safe_redirect( $url );
           exit;
       }
   }
   

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