Changeset 35717 for trunk/src/wp-admin/includes/template-functions.php

Timestamp:

11/20/2015 06:15:34 AM (11 years ago)

Author:

helen

Message:

Custom fields: Allow for short-circuiting the meta key dropdown.

Adds the postmeta_form_keys filter which allows for a potentially expensive query against postmeta to be avoided.

props ericmann, tollmanz, nacin.
see #33885.

File:

• trunk/src/wp-admin/includes/template-functions.php (modified) (1 diff)

trunk/src/wp-admin/includes/template-functions.php

@@ -578 +578 @@
 
         /**
-         * Filter the number of custom fields to retrieve for the drop-down
-         * in the Custom Fields meta box.
+         * Filter values for the meta key dropdown in the Custom Fields meta box.
          *
-         * @since 2.1.0
+         * Returning a non-null value will effectively short-circuit and avoid a
+         * potentially expensive query against postmeta.
          *
-         * @param int $limit Number of custom fields to retrieve. Default 30.
+         * @since 4.4.0
+         *
+         * @param array|null $keys Pre-defined meta keys to be used in place of a postmeta query. Default null.
          */
-        $limit = apply_filters( 'postmeta_form_limit', 30 );
-        $sql = "SELECT DISTINCT meta_key
-                FROM $wpdb->postmeta
-                WHERE meta_key NOT BETWEEN '_' AND '_z'
-                HAVING meta_key NOT LIKE %s
-                ORDER BY meta_key
-                LIMIT %d";
-        $keys = $wpdb->get_col( $wpdb->prepare( $sql, $wpdb->esc_like( '_' ) . '%', $limit ) );
+        $keys = apply_filters( 'postmeta_form_keys', null );
+
+        if ( null === $keys ) {
+                /**
+                 * Filter the number of custom fields to retrieve for the drop-down
+                 * in the Custom Fields meta box.
+                 *
+                 * @since 2.1.0
+                 *
+                 * @param int $limit Number of custom fields to retrieve. Default 30.
+                 */
+                $limit = apply_filters( 'postmeta_form_limit', 30 );
+                $sql = "SELECT DISTINCT meta_key
+                        FROM $wpdb->postmeta
+                        WHERE meta_key NOT BETWEEN '_' AND '_z'
+                        HAVING meta_key NOT LIKE %s
+                        ORDER BY meta_key
+                        LIMIT %d";
+                $keys = $wpdb->get_col( $wpdb->prepare( $sql, $wpdb->esc_like( '_' ) . '%', $limit ) );
+        }
+
         if ( $keys ) {
                 natcasesort( $keys );