Remove Menu Page Giving Error

Question

I have a snippet of code I've written in the functions.php file which is simply to remove menu pages if the user cannot activate plugins. It works as intended; however it is showing a PHP error in the admin area only if the logged in user is an administrator.

Here's the code snippet:

<?php
/************ Remove admin menu items from anyone who isn't an admin ************/

if (!current_user_can('activate_plugins') ) { 
    function my_remove_menu_pages() {
        remove_menu_page('link-manager.php');
        remove_menu_page('tools.php');
        remove_menu_page('edit-comments.php');
    }
};

add_action( 'admin_menu', 'my_remove_menu_pages' );
?>

Here's the error:

Warning: call_user_func_array() expects parameter 1 to be a valid callback, function 'my_remove_menu_pages' not found or invalid function name in /var/www/vhosts/mydomain.com/httpdocs/wp-includes/plugin.php on line 406

I've tried rewriting the snippet a couple different ways, and each time it basically does the same thing. Works as intended, removing admin menu pages for less than admins, but gives the same error in the WP backend when logged in as admin. Any suggestions or thoughts on this?

Answer 1

Put the add_action line inside the if (!current_user_can('activate_plugins') ) {:

<?php
/************ Remove admin menu items from anyone who isn't an admin ************/

if (!current_user_can('activate_plugins') ) { 
    function my_remove_menu_pages() {
        remove_menu_page('link-manager.php');
        remove_menu_page('tools.php');
        remove_menu_page('edit-comments.php');
    }

    add_action( 'admin_menu', 'my_remove_menu_pages' );
};
?>

Answer 2

You are only defining your function when a user cannot 'activate_plugins' but you are attempting to use the function all the time. You'd be better off doing what Mike Madern suggested in a comment:

if (!current_user_can('activate_plugins') ) { 
    function my_remove_menu_pages() {
        remove_menu_page('link-manager.php');
        remove_menu_page('tools.php');
        remove_menu_page('edit-comments.php');
    }

    add_action( 'admin_menu', 'my_remove_menu_pages' );
}

Or this:

function my_remove_menu_pages() {
    remove_menu_page('link-manager.php');
    remove_menu_page('tools.php');
    remove_menu_page('edit-comments.php');
}

if (!current_user_can('activate_plugins') ) { 
    add_action( 'admin_menu', 'my_remove_menu_pages' );
}

That should get rid of the Warning. I am still concerned about this though. You should be able to show and hide the various pages by manipulating user Roles and Capabilities. That is how I'd suggest you do this, rather than just brute force removing admin pages. You may cause yourself some trouble that way. You will need a plugin to do any detailed manipulation of user capabilities or write your own code for it.