flutter firebase get string from database using future - firebase

Question

I want to get a string from my DB in Firebase, I'm very confused and I don't know how to do that!
I made a big search in the few past days about this idea but unf I don't get any useful result
what do I want? I want to make a Method that returns the 'Question' string.
DB:Collection / History/question
thank you for your time
the incorrect code :
Future loadData() async {
await Firebase.initializeApp();
if (snapshot.hasError) {
return Scaffold(
body: Center(
child: Text("Error: ${snapshot.error}"),
),
);
}
// Collection Data ready to display
if (snapshot.connectionState == ConnectionState.done) {
// Display the data inside a list view
return snapshot.data.docs.map(
(document) {
return method(
document.data()['question'].toString().toString(),
); //Center(
},
);
}
}

Answer 1

Here is the official documentation from Flutter Fire - https://firebase.flutter.dev/docs/firestore/usage/
Read data from Cloud firestore
Cloud Firestore gives you the ability to read the value of a collection or a document. This can be a one-time read or provided by real-time updates when the data within a query changes.
One-time Read
To read a collection or document once, call the Query.get or DocumentReference.get methods. In the below example a FutureBuilder is used to help manage the state of the request:
class GetUserName extends StatelessWidget {
final String documentId;
GetUserName(this.documentId);
#override
Widget build(BuildContext context) {
CollectionReference users = FirebaseFirestore.instance.collection('users');
return FutureBuilder<DocumentSnapshot>(
future: users.doc(documentId).get(),
builder:
(BuildContext context, AsyncSnapshot<DocumentSnapshot> snapshot) {
if (snapshot.hasError) {
return Text("Something went wrong");
}
if (snapshot.hasData && !snapshot.data.exists) {
return Text("Document does not exist");
}
if (snapshot.connectionState == ConnectionState.done) {
Map<String, dynamic> data = snapshot.data.data();
return Text("Full Name: ${data['full_name']} ${data['last_name']}");
}
return Text("loading");
},
);
}
}
To learn more about reading data whilst offline, view the Access Data Offline documentation.
Realtime changes
FlutterFire provides support for dealing with real-time changes to collections and documents. A new event is provided on the initial request, and any subsequent changes to collection/document whenever a change occurs (modification, deleted, or added).
Both the CollectionReference & DocumentReference provide a snapshots() method which returns a Stream:
Stream collectionStream = FirebaseFirestore.instance.collection('users').snapshots();
Stream documentStream = FirebaseFirestore.instance.collection('users').doc('ABC123').snapshots();
Once returned, you can subscribe to updates via the listen() method. The below example uses a StreamBuilder which helps automatically manage the streams state and disposal of the stream when it's no longer used within your app:
class UserInformation extends StatefulWidget {
#override
_UserInformationState createState() => _UserInformationState();
}
class _UserInformationState extends State<UserInformation> {
final Stream<QuerySnapshot> _usersStream = FirebaseFirestore.instance.collection('users').snapshots();
#override
Widget build(BuildContext context) {
return StreamBuilder<QuerySnapshot>(
stream: _usersStream,
builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
if (snapshot.hasError) {
return Text('Something went wrong');
}
if (snapshot.connectionState == ConnectionState.waiting) {
return Text("Loading");
}
return new ListView(
children: snapshot.data.docs.map((DocumentSnapshot document) {
return new ListTile(
title: new Text(document.data()['full_name']),
subtitle: new Text(document.data()['company']),
);
}).toList(),
);
},
);
}
}
By default, listeners do not update if there is a change that only affects the metadata. If you want to receive events when the document or query metadata changes, you can pass includeMetadataChanges to the snapshots method:
FirebaseFirestore.instance
.collection('users')
.snapshots(includeMetadataChanges: true)