如何从 Flutter 中的 Firestore 获取值

Question

I need to get the values inside my Firestore document which has a sub collection.

ADD DATA TO DB

In adding, what I try to accomplish is on the userPolls collection, I need to add a document with an Id based on the userId then create a collection of 'dailyPolls' that has a document with an Id of the current date but without the '/' and in it is where I put all my data like so:

final CollectionReference userPollCollection =
      Firestore.instance.collection('userPolls');
Future setPoll(UserPoll userPoll) async {
    var dt = userPoll.pollDate.replaceAll('/', '');
    return await userPollCollection
        .document(userId)
        .collection('daillyPolls')
        .document(dt)
        .setData({
      'uid': userId,
      'pollDate': userPoll.pollDate,
      'status': userPoll.status,
      'statusCode': userPoll.statusCode
    });
  }

QUERYING DATA FROM DB

In retrieving data, I need to get to the userPolls , then get the document with an Id which is the userId , then go to the collection of dailyPolls , then get the document with an Id which is based on the current date without the '/' then get the data which is inside it.

 Future getPoll() async {
    final DateTime now = DateTime.now();
    final DateFormat formatter = DateFormat('yyyy/MM/dd');
    final String formatted = formatter.format(now);
    var pollDate = formatted;
    var dt = pollDate.replaceAll('/', '');

    var docRef = userPollCollection
        .document(userId)
        .collection('dailyPolls')
        .document(dt);

    docRef.get().then((onValue) {
      print(onValue.data);
    });
  }

The red square is the path and the blue is what I need

I am very new to flat databases.

Answer 1

I'm not sure what the classes are you are trying to use, but here is the simplest way I can get a date in the right format:

final DateTime now = DateTime.now();
final DateFormat formatter = DateFormat('yyyy/MM/dd');
final String formatted = formatter.format(now);

print(formatted);

var docRef = userPollCollection
    .document(userId)
    .collection('dailyPolls')
    .document(formatted);

To then get the status field, you'd do:

docRef.get().then((onValue) {
  print(onValue.data().status);
});

If you're still having problem, check the output of the first print statement to see if its value matches what you see in the database.