How to use postmeta_form_keys filter in WordPress

postmeta_form_keys filter

Filters values for the meta key dropdown in the Custom Fields meta box.

apply_filters( 'postmeta_form_keys', array|null $keys, WP_Post $post )

Description

This is filter hook , its filter values for the meta key dropdown in the Custom Fields meta box..
Returning a non-null value will effectively short-circuit and avoid a potentially expensive query against postmeta.
Its consists of two parameters, one is $keys, second is $post object.
Its used by meta_form() which print the form in the Custom Fields meta box.

Parameters

• $keys : (array|null) Pre-defined meta keys to be used in place of a postmeta query. Default null.
• $post : (WP_Post) The current post object.

Live Example

To run the hook, copy the example below.

apply_filters( 'postmeta_form_keys', array|null $keys, WP_Post $post )

The following example is for adding a hook callback.

add_filter('postmeta_form_keys','meta_form_keys');

function meta_form_keys($keys, $post ) {
   
    return $keys;
}

To remove a hook callback, use the example below.

// remove the filter 
add_filter( 'postmeta_form_keys', 'meta_form_keys', 10, 1 );