Changeset 35717

Timestamp:

11/20/2015 06:15:34 AM (9 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 );