StreamBuilder always returning false in print(snapshot.hasData) in flutter

Question

i will showing message from firebase firestore in flutter , but when i make conditional in snapshot always returning false this is my code

Service

Stream<List<MessageModel>> getMessagesByUserid({int userId}) {
    try {
      return firestore
          .collection('messages')
          .where('userId', isEqualTo: userId)
          .snapshots()
          .map((QuerySnapshot list) {
        var result = list.docs.map<MessageModel>((DocumentSnapshot message) {
          print('from service : ' + message.data().toString());
          return MessageModel.fromJson(message.data());
        }).toList();

        result.sort(
          (MessageModel a, MessageModel b) =>
              a.createdAt.compareTo(b.createdAt),
        );
        return result;
      });
    } catch (e) {
      throw Exception(e);
    }
  }

and call with this

 Widget content() {
      return StreamBuilder<List<MessageModel>>(
          stream: MessageService()
              .getMessagesByUserid(userId: authprovider.user.id),
          builder: (context, snapshot) {
            print(snapshot.hasData);
            if (snapshot.hasData) {
              return ListView(
                padding: EdgeInsets.symmetric(
                  horizontal: defaultMargin,
                ),
                children: snapshot.data
                    .map(
                      (MessageModel message) => ChatBubble(
                        isSender: message.isFromUser,
                        text: message.message,
                        product: message.product,
                      ),
                    )
                    .toList(),
              );
            } else {
              return Center(
                child: CircularProgressIndicator(),
              );
            }
          });
    }

when i print in service , i get

I/flutter (29881): from service : {createdAt: 2021-06-28 16:29:25.106709, product: {}, userImage: https://ui-avatars.com/api/?name=eka&color=7F9CF5&background=EBF4FF, isFromUser: true, message: tanpa, userName: eka, userId: 2, updatedAt: 2021-06-28 16:29:25.106811}

but when i print(snapshot.hasData) always returning false

I/flutter (29881): false

Answer 1

If you require more granularity when using StreamBuilder then test snapshot.connectionState rather than snapshot.hasData.

snapshot.hasData can still be false if the Stream is returning null