onKey method

Stream<K?> onKey(
  1. Database database
)

Find first record key (null if none) and listen for changes.

Returns a single subscriber stream that must be cancelled.

Implementation

Stream<K?> onKey(Database database) {
  if (sembastQueryRef.finder?.limit != 1) {
    return SembastQueryRef(
      sembastQueryRef.store,
      cloneFinderFindFirst(sembastQueryRef.finder),
    ).onKey(database);
  }

  /// We know the list is limited to 1 here
  return onKeys(database).map((list) => list.isNotEmpty ? list.first : null);
}