How can I add the ability for a user to add/edit administrators?

Question

I created a new user role called "developer" and I gave it all of administrator's capabilities:

$admin_role = get_role( 'administrator' );
add_role( 'developer', __( 'Developer' ), $admin_role->capabilities );

This works great except I'd like Developers to be able to add/edit Administrator users. However, when I add a new user, "Administrator" isn't one of the options in the user role dropdown list.

I tried having the editable_roles filter return all of the roles in the system, so that the Developer can add/edit all roles:

add_filter( 'editable_roles', 'allow_developers_to_add_administrators' );
function allow_developers_to_add_administrators( $roles ){
  $user = wp_get_current_user();
  if( in_array( 'developer', $user->roles )){
    return array_keys( $GLOBALS['wp_roles']->roles );
  }
  return $roles;
}

But when I do that, the roles dropdown list only shows the 1st letter of each role (they have a custom set of roles and this is showing the first letter for each one):

I also tried simply appending 'administrator' to the $roles returned from the editable_roles filter, but it - predictably - just added an item with 'a' to the dropdown list.

Anyone know how I can make this work? (Note that I'm not on multisite so I don't think there's a super admin role I can hook into here)

Thanks!
Abby

Answer 1

Make sure you're adding and removing roles on plugin activation/deactivation.

add_role() only adds a role if it doesn't already exist. So if you already added the developer role without the capability to add administrators, calling add_role() again won't re-add the role. You have to remove the role first.

<?php
/**
 * Plugin Name: Stackexchange Sample
 */

//* Don't access this file directly
defined( 'ABSPATH' ) or die();

//* Add role for developer that has the same capabilities as administrators
register_activation_hook( __FILE__ , 'wpse_106269_activation' );
function wpse_106269_activation() {
  $admin_role = get_role( 'administrator' );
  add_role( 'developer', __( 'Developer' ), $admin_role->capabilities );
}

//* Remove developer role
register_deactivation_hook( __FILE__ , 'wpse_106269_deactivation' );
function wpse_106269_activation() {
  remove_role( 'developer' );
}

Deactivate and re-activate your plugin and the developer role should have the same capabilities as the administrator role.