Retrieve data from firebase firestore using flutter

Question

I am trying to get data from the following path in Flutter from cloud Firestore and I have the following structure

followers/{currentuser}/userFollowers/{user_id}
users/user_id/user_details

I am trying to get details of all the followers for the current user. Can anyone help?

i was able to get the first part by

DocumentSnapshot snapshot =
        await followersRef.document(currentUser.id).get();

I do not know how to loop thru all the id's to fetch their data from users collections. I was trying the following code but no success.

snapshot.data.forEach((key, value) async {
      DocumentSnapshot snapshot2 =
          await usersRef.document(snapshot.documentID).get();
      print('List' + snapshot2.data);
    }

so i was able to get list of id for followers with 'DocumentSnapshot snapshot = await followersRef.document(currentUser.id).get();' snapshot.data.forEach((key, value) async { DocumentSnapshot snapshot2 = await usersRef.document(snapshot.documentID).get(); print('List' + snapshot2.data.length.toString()); }); — Harshal Gandhi
Can you share a snapshot with a sample of you data on both documents? so we can compare the expected data? — Rafael Lemos

Rafael Lemos Rafael Lemos · Accepted Answer · 2020-03-25T10:48:51

You could do something like this:

final db = Firestore.instance;
final uid = firebase.auth().currentUser.uid;

var userDetails = [];
var data = db.collection("followers").doc(uid).collection("userFollowers").get()
 .then(function(querySnapshot) {
    querySnapshot.forEach(function(doc) {
        userDetails.add(db.collection("users").doc(doc.user_id)
          .collection("user_details").get())
    });
});

NOTE: You could simplify this by adding all follower IDs to a followersID array on each current user document, this would increase performance and decrease both number of reads and amount of data managed by your app.

Retrieve data from firebase firestore using flutter

1 Answers