How to use register_meta_args filter in WordPress

Welcome to the in-depth guide on the register_meta_args filter hook! This hook filters the registration arguments when registering meta in WordPress. As a fellow developer, I’m here to walk you through how to use this hook effectively.

To use the register_meta_args filter, you need to register it using add_filter. You can write this code in the functions.php of your activated theme or in a custom WordPress plugin. At WePlugins, we always prefer to create a custom WordPress plugin to ensure nothing breaks when you update your WordPress theme in the future.

In the examples below, we define a function weplugins_modify_register_meta_args_defaults which takes four parameters and registers it using add_filter. The first parameter, register_meta_args, is the name of the hook. The second parameter, weplugins_modify_register_meta_args_defaults, is the name of the function 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 to the registered function.

Sometimes, you might need to remove a registered hook, and you can use remove_filter to remove the register_meta_args filter.

Parameters

Below are the 4 parameters required to use this hook:

• $args: (array) Array of meta registration arguments.
• $defaults: (array) Array of default arguments.
• $object_type: (string) Type of object metadata is for. Accepts ‘post’, ‘comment’, ‘term’, ‘user’, or any other object type with an associated meta table.
• $meta_key: (string) Meta key.

Live Example 1: Basic Usage

Here’s a simple example of how you can use this hook to modify the registration arguments:

function weplugins_modify_register_meta_args_defaults($args, $defaults, $object_type, $meta_key) { 
    // Update the $args variable according to your website requirements and return this variable. You can modify the $args variable conditionally too if you want.
    return $args; 
}
// Add the filter
add_filter( "register_meta_args", "weplugins_modify_register_meta_args_defaults", 10, 4 );

Live Example 2: Removing a Hook Callback

To remove a hook callback, use the example below:

remove_filter( "register_meta_args", "weplugins_modify_register_meta_args_defaults", 10, 4 );

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

Live Example 3: Conditional Modification

In this example, we conditionally modify the $args variable based on the $object_type:

function weplugins_modify_register_meta_args_defaults($args, $defaults, $object_type, $meta_key) { 
    if ($object_type === 'post') {
        // Modify the $args array for posts
        $args['single'] = true;
    }
    return $args; 
}
// Add the filter
add_filter( "register_meta_args", "weplugins_modify_register_meta_args_defaults", 10, 4 );

If you need any customization or encounter issues using this hook, feel free to Contact Us for assistance.