Ticket #40012: 40012.diff

src/wp-includes/meta.php

@@ -21 +21 @@
  * @param int    $object_id  ID of the object metadata is for
  * @param string $meta_key   Metadata key
  * @param mixed  $meta_value Metadata value. Must be serializable if non-scalar.
- * @param bool   $unique     Optional, default is false.
+ * @param mixed  $unique     Optional, default is false.
  *                           Whether the specified metadata key should be unique for the object.
  *                           If true, and the object already has a value for the specified metadata key,
  *                           no change will be made.
+ *                           If 'value', and the object already has the same metadata value being added
+ *                           for the specified metadata key, no change will be made.
  * @return int|false The meta ID on success, false on failure.
  */
 function add_metadata($meta_type, $object_id, $meta_key, $meta_value, $unique = false) {
@@ -64 +66 @@
          * @param int       $object_id  Object ID.
          * @param string    $meta_key   Meta key.
          * @param mixed     $meta_value Meta value. Must be serializable if non-scalar.
-         * @param bool      $unique     Whether the specified meta key should be unique
+         * @param mixed     $unique     Whether the specified meta key should be unique
          *                              for the object. Optional. Default false.
          */
         $check = apply_filters( "add_{$meta_type}_metadata", null, $object_id, $meta_key, $meta_value, $unique );
         if ( null !== $check )
                 return $check;
 
-        if ( $unique && $wpdb->get_var( $wpdb->prepare(
-                "SELECT COUNT(*) FROM $table WHERE meta_key = %s AND $column = %d",
-                $meta_key, $object_id ) ) )
-                return false;
+        if ( false !== $unique ) {
+                if ( 'value' === $unique ) {
+                        $sql = $wpdb->prepare( "SELECT COUNT(*) FROM {$table} WHERE meta_key = %s AND meta_value = %s AND {$column} = %d", $meta_key, $meta_value, $object_id );
+                } else {
+                        $sql = $wpdb->prepare( "SELECT COUNT(*) FROM {$table} WHERE meta_key = %s AND {$column} = %d", $meta_key, $meta_value, $object_id );
+                }
 
+                if ( $wpdb->get_var( $sql ) ) {
+                        return false;
+                }
+        }
+
         $_meta_value = $meta_value;
         $meta_value = maybe_serialize( $meta_value );