CODEWITHSUNDEEP
firebasefluttergoogle-cloud-firestore
Milly Alfaro
Milly Alfaro

Reputation: 309

How to properly access a collection's data to be used for a list in flutter with Firestore

So I need to get access to a piece of data called groupId which will be used as a doc path for a collection called Members that I will be used to retrieve data from and put in a list. The problem is that it requires an async which I don't know where to put as I get errors. Here's the code:

@override
  Widget build(BuildContext context) {
    final CollectionReference users = firestore.collection('UserNames');

    final String uid = auth.currentUser.uid;

    final result = await users.doc(uid).get(); //This await requires an async but I don't how to do that

    final groupId = result.data()['groupId'];
    // <1> Use FutureBuilder
    return FutureBuilder<QuerySnapshot>(
        // <2> Pass `Future<QuerySnapshot>` to future
        future: FirebaseFirestore.instance.collection('Groups').doc(groupId).collection('Members').get(), //Once the async problem is solved i will be able to save the groupId as. variable to be used in my doc path to access this collection.  How do I do this?
        builder: (context, snapshot) {
          if (snapshot.hasData) {
            // <3> Retrieve `List<DocumentSnapshot>` from snapshot
            final List<DocumentSnapshot> documents = snapshot.data.docs;
            return ListView(
                children: documents
                    .map((doc) => Card(
                          child: ListTile(
                            title: Text(doc['displayName']),
                            subtitle: Text(doc['plastics'].toString()),
                          ),
                        ))
                    .toList());
          } else if (snapshot.hasError) {
            return Text('Its Error!');
          }
        });
  }

Upvotes: 0

Views: 175

Answers (1)

Glen
Glen

Reputation: 619

Wrap your FutureBuilder in another FutureBuilder.

users.doc(uid).get() returns a Future. If you are using it in a widget, you use FutureBuilder.

await and futureBuilder do the similar things


    @override
  Widget build(BuildContext context) {
    final CollectionReference users = firestore.collection('UserNames');

    final String uid = auth.currentUser.uid;

    return FutureBuilder(
        future: users.doc(uid).get(),
        builder: (context, snapshot) {
          if (snapshot.hasData) {
            final result = snapshot.data;
            final groupId = result.data()['groupId'];
            return FutureBuilder<QuerySnapshot>(
                // <2> Pass `Future<QuerySnapshot>` to future
                future: FirebaseFirestore.instance
                    .collection('Groups')
                    .doc(groupId)
                    .collection('Members')
                    .get(), //Once the async problem is solved i will be able to save the groupId as. variable to be used in my doc path to access this collection.  How do I do this?
                builder: (context, snapshot) {
                  if (snapshot.hasData) {
                    // <3> Retrieve `List<DocumentSnapshot>` from snapshot
                    final List<DocumentSnapshot> documents = snapshot.data.docs;
                    return ListView(
                        children: documents
                            .map((doc) => Card(
                                  child: ListTile(
                                    title: Text(doc['displayName']),
                                    subtitle: Text(doc['plastics'].toString()),
                                  ),
                                ))
                            .toList());
                  } else if (snapshot.hasError) {
                    return Text('Its Error!');
                  }
                });
          }
        });
  }

Upvotes: 1

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