How to use mu_plugin_loaded action in WordPress

mu_plugin_loaded action

Fires once a single must-use plugin has loaded.

To use mu_plugin_loaded action, first you have to register it using add_action. You can write this code into functions.php of your activated theme or in a custom WordPress Plugin.

We at WePlugins always prefer to create a custom WordPress Plugin while using hooks so nothing breaks when you update your WordPress Theme in the future.

In the below live example, we have defined a function weplugins_execute_on_mu_plugin_loaded_event which takes 1 parameter and we registered it using add_action. The first parameter mu_plugin_loaded is the name of the hook, the second parameter weplugins_execute_on_mu_plugin_loaded_event is the name of the function which needs to be called, the third parameter is the priority of calling the hook if the same hook is used multiple times, and the last parameter is the number of arguments (if any) to be passed in the registered function.

Sometimes, you have to remove a registered hook so you can use remove_action to remove mu_plugin_loaded action.

Parameters

Below the 1 parameter is required to use this hook.

• $mu_plugin : (string) Full path to the plugin’s main file.

Live Example 1: Adding the Action

Below is an example of how you can use this hook.

    function weplugins_execute_on_mu_plugin_loaded_event($mu_plugin){
       // You can write code here to be executed when this action occurs in WordPress.
       // Use the parameters received in the function arguments & implement the required additional custom functionality according to your website requirements.
    }
    // add the action
    add_action( "mu_plugin_loaded", "weplugins_execute_on_mu_plugin_loaded_event" , 10, 1);
    

Live Example 2: Removing the Action

To remove a hook callback, use the example below.

    remove_action( "mu_plugin_loaded", "weplugins_execute_on_mu_plugin_loaded_event", 10, 1 );
    

Please make sure to provide the same callback function name, priority, and number of arguments while removing the hook callback.

Live Example 3: Modifying the Action

You might want to modify what happens when the mu_plugin_loaded hook is fired. Below is how you can do that.

    function weplugins_execute_on_mu_plugin_loaded_event_modified($mu_plugin){
       // Modified code to be executed when this action occurs in WordPress.
    }
    // remove the old action
    remove_action( "mu_plugin_loaded", "weplugins_execute_on_mu_plugin_loaded_event", 10, 1 );
    // add the new action
    add_action( "mu_plugin_loaded", "weplugins_execute_on_mu_plugin_loaded_event_modified" , 10, 1);
    

Contact Us

If you’re having any trouble using this hook, please contact our WordPress Development Team and we’d be happy to assist you.