Function and usage of map_meta_cap() in wordpress


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    The map_meta_cap() function in WordPress is a crucial component for understanding and managing user capabilities and permissions. Here's a detailed explanation of its function, parameters, and sample usage:


    • Name: map_meta_cap()
    • Purpose: Maps a meta capability to the primitive capabilities required for a user to satisfy the given capability.


    • The map_meta_cap() function is used to translate a meta capability into one or more primitive capabilities.
    • Meta capabilities are high-level capabilities like edit_post or edit_user that depend on the context, such as the specific post or user being edited.
    • Primitive capabilities are more straightforward, like edit_posts or edit_others_posts, and do not depend on specific objects.
    • When a meta capability is checked, map_meta_cap() determines which primitive capabilities are necessary for a user to have in order to satisfy the meta capability in the given context.
    • This function is particularly useful in scenarios where capabilities need to be checked in relation to specific objects, like a particular post or user.
    • It does not perform any actual permission checks; it simply maps one type of capability to another.


    1. $cap (string, required): The meta capability being checked. Example: 'edit_post'.
    2. $user_id (int, required): The ID of the user whose capabilities are being evaluated.
    3. $args (mixed, optional): Additional arguments, typically starting with an object ID related to the capability. This could be a post ID, a comment ID, etc., depending on the context.


    • Type: string[]
    • Description: An array of primitive capabilities required for the user to satisfy the meta capability.

    Example Usage:

    1. Checking 'edit_posts' Capability:

      map_meta_cap( 'edit_posts', $user->ID );

      This checks what primitive capabilities are required for a user to have the 'edit_posts' capability.

    2. Checking 'edit_post' for a Specific Post:

      map_meta_cap( 'edit_post', $user->ID, $post->ID );

      This checks the primitive capabilities needed for a user to edit a specific post.

    3. Checking 'edit_post_meta' for a Specific Post and Meta Key:

      map_meta_cap( 'edit_post_meta', $user->ID, $post->ID, $meta_key );

      This is used to determine what capabilities a user needs to edit the metadata of a specific post.

    In conclusion, map_meta_cap() is a function that helps developers understand the required primitive capabilities for performing certain actions in WordPress, especially when these actions are context-specific (like editing a particular post). It's a backend tool used for capability management and is essential for developing plugins and themes that interact with WordPress's permission system.

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