I am trying to fetch data from firebase and add it to a list but the list always comes empty [closed]

Question

I created a function fetch tasks to access the collection timestamps and retrieve its documents and place them into a list but for some reason the list always comes out empty. To replicate the error you would need to create a firebase database of the format User --> (doc) --> Tasks --> (doc) --> Timestamp --> (date) --> StartStop --> (doc) --> (field called either start or stop with a time value). Here is the code of the function:

void _fetchTasks() async {
    try {
      final currentUser = FirebaseAuth.instance.currentUser;
      if (currentUser != null) {
        final querySnapshot = await FirebaseFirestore.instance
            .collection('Users')
            .doc(currentUser.uid)
            .collection('Tasks')
            .where('status', isEqualTo: 'active') // Filter by status 'active'
            .get();

        List<TaskData> data = [];

        for (var doc in querySnapshot.docs) {
          final taskData = doc.data();
          String taskName = taskData['name'] ?? 'Unknown';
          int color = taskData['color'] ?? Colors.grey.value;

          final timestampsSnapshot = await FirebaseFirestore.instance
              .collection('Users')
              .doc(currentUser.uid)
              .collection('Tasks')
              .doc(doc.id)
              .collection('Timestamps')
              .get();

          print('Timestamps snapshot for task: $taskName - ${timestampsSnapshot.docs.length} documents found');

          for (var timestampDoc in timestampsSnapshot.docs) {
            print('Processing timestamp document ID: ${timestampDoc.id}');
            CollectionReference startStopRef = FirebaseFirestore.instance
                .collection('Users')
                .doc(currentUser.uid)
                .collection('Tasks')
                .doc(doc.id)
                .collection('Timestamps')
                .doc(timestampDoc.id)
                .collection('StartStop');

            print('StartStop reference: $startStopRef');
            QuerySnapshot startStopSnapshot = await startStopRef.get();

            print('StartStop snapshot: ${startStopSnapshot.docs.length} documents found');

            List<DateTime> startStopTimes = [];

            for (var startStopDoc in startStopSnapshot.docs) {
              var startStopData = startStopDoc.data() as Map<String, dynamic>;

              print('Start/Stop data: $startStopData');

              if (startStopData.containsKey('start')) {
                startStopTimes.add(_parseTimeString(startStopData['start'], timestampDoc.id));
              } else if (startStopData.containsKey('stop')) {
                startStopTimes.add(_parseTimeString(startStopData['stop'], timestampDoc.id));
              }
            }

            startStopTimes.sort();
            print('Sorted startStopTimes: $startStopTimes');

            for (int i = 0; i < startStopTimes.length - 1; i += 2) {
              DateTime start = startStopTimes[i];
              DateTime stop = startStopTimes[i + 1];

              int duration = stop.difference(start).inMinutes;
              data.add(TaskData(taskName, color, duration, timestampDoc.id));
              print('TaskData added: $taskName, $duration minutes on ${timestampDoc.id}');
            }
          }
        }

        setState(() {
          _data = data;
          _generateData(_data);
        });

        print('Data fetched successfully. Data length: ${data.length}');
        if (_data.isNotEmpty) {
          print('Sample data: ${_data[0].name}, ${_data[0].duration} minutes on ${_data[0].day}');
        }
      } else {
        print('No user is currently signed in.');
      }
    } catch (error) {
      print('Error fetching tasks: $error');
    }
  }

  DateTime _parseTimeString(String timeString, String date) {
    try {
      final dateTimeString = '$date $timeString';
      return DateTime.parse(dateTimeString);
    } catch (e) {
      print('Error parsing time string: $timeString for date: $date. Error: $e');
      return DateTime.now();  // Return current time to avoid null issues
    }
  }

I tried modifying my firebase database structure but it is the same used in the function so I don't see what could be the problem.