whereFilter method

Query<T> whereFilter(Filter filter)

Creates and returns a new Query with the additional filter that documents should satisfy the relation constraint(s) provided.

This function returns a new (immutable) instance of the Query (rather than modify the existing instance) to impose the filter.

• filter A unary or composite filter to apply to the Query.

final collectionRef = firestore.collection('col');

collectionRef.where(Filter.and(Filter.where('foo', WhereFilter.equal, 'bar'), Filter.where('foo', WhereFilter.notEqual, 'baz'))).get()
  .then((querySnapshot) {
    querySnapshot.forEach((documentSnapshot) {
      print('Found document at ${documentSnapshot.ref.path}');
    });
});

Implementation

Query<T> whereFilter(Filter filter) {
  if (_queryOptions.startAt != null || _queryOptions.endAt != null) {
    throw ArgumentError(
      'Cannot specify a where() filter after calling '
      'startAt(), startAfter(), endBefore() or endAt().',
    );
  }

  final parsedFilter = _parseFilter(filter);
  if (parsedFilter.filters.isEmpty) {
    // Return the existing query if not adding any more filters (e.g. an empty composite filter).
    return this;
  }

  final options = _queryOptions.copyWith(
    filters: [..._queryOptions.filters, parsedFilter],
  );
  return Query<T>._(
    firestore: firestore,
    queryOptions: options,
  );
}