Restrict Media Library by User Role

restrict-media-library.php

<?php
/**
 * Restrict Media Library by User Role
 * 
 * @package     Restrict_Media_Library
 * @since       1.0.0
 * @author      hellofromTonya
 */

/**
 * Hook into the Posts WHere filter to restrict the Media Library
 * if the current user is not the admin.
 *
 * @since 1.0.0
 *
 * @return null
 */
add_action( 'admin_init', function() {

	if ( ! current_user_can( 'manage_options' ) ) {
		add_filter( 'posts_where', 'build_media_library_where_sql_based_on_user_role' );
	}
} );

/**
 * Build the WHERE SQL for the Media Library based on user role
 *
 * @since 1.0.0
 *
 * @param string $where_sql
 * @return string
 */
function build_media_library_where_sql_based_on_user_role( $where_sql ) {

	if ( ! isset( $_POST['action'] ) || 'query-attachments' != $_POST['action'] ) {
		return $where_sql;
	}

	// Get all the user IDs for this current user's role
	$user_ids = get_user_ids_based_on_current_user_role();
	if ( false === $user_ids ) {
		return $where_sql;
	}

	// Sanitize the IDs
	sanitize_user_ids( $user_ids );

	// Modify the WHERE SQL statement and return
	return sprintf( '%s AND post_author IN ( %s )', $where_sql, implode( ',', $user_ids ) );
}

/**
 * Get all of the user IDs based on the current user's role
 *
 * @since 1.0.0
 *
 * @return array|bool
 */
function get_user_ids_based_on_current_user_role() {

	global $current_user;

	$user_ids = get_users( array(
		'role'      => $current_user->roles[0],
		'orderby'   => 'ID',
		'fields'    => 'ID',
	) );

	return is_array( $user_ids ) && ! empty( $user_ids ) ? $user_ids : false;
}

/**
 * Sanitize the user IDs
 *
 * @since 1.0.0
 *
 * @param array     $user_ids   Passed by reference
 */
function sanitize_user_ids( array &$user_ids ) {

	global $wpdb;

	foreach ( $user_ids as $key => $id ) {
		$user_ids[ $key ] = $wpdb->prepare( '%d', $id );
	}
}