Flutter: CRUD clarifications over Firebase - firebase

Question

I've been working on a little project on flutter since I just started learning it a week ago and I'm just wondering how I could retrieve a specific snippet of data from Firebase's Firestore database.
Here is the code on the relevant files:
database.dart
import 'package:plannus/models/user.dart';
class DatabaseMethods {
final String uid;
DatabaseMethods({this.uid});
final CollectionReference users = Firestore.instance.collection("users");
Future<void> updateUserData(String name, String handle) async {
print(uid);
return await users.document(uid).updateData({
'name' : name,
'handle' : handle,
});
}
Future<void> updateSpecificUserData(String uid, String name, String handle) async {
print(uid);
return await users.document(uid).updateData({
'name' : name,
'handle' : handle,
});
}
Future<Set<Set<String>>> getUserData() {
return users.document(uid).get().then((value) => {
if (value.exists) {
value.data['handle']
}
});
}
void getSpecificUserData(String uid, String capture) async {
DocumentSnapshot snapshot = await users.document(uid).get();
capture = snapshot.data['handle'];
print(capture);
}
Future<String> retrieveData(String uid) async {
DocumentSnapshot snap = await users.document(uid).get();
Map<String, String> map = snap.data;
String handle = map['name'];
return handle;
}
//
uploadUserInfo(userMap) {
Firestore.instance.collection("users").add(userMap);
}
// user data from snapshot
Stream<QuerySnapshot> get userInfo {
return users.snapshots();
}
}
profile.dart
import 'package:flutter/material.dart';
import 'package:plannus/messages/database.dart';
import 'package:plannus/models/user.dart';
import 'package:plannus/services/auth.dart';
import 'package:provider/provider.dart';
class Profile extends StatefulWidget {
#override
_ProfileState createState() => _ProfileState();
}
class _ProfileState extends State<Profile> {
final AuthService auth = AuthService();
final formKey = GlobalKey<FormState>(); // 'id' of form
bool loading = false;
// text field state
String name = '';
String password = '';
String handle = '';
String error = '';
DatabaseMethods databaseMethods = new DatabaseMethods();
QuerySnapshot currentUser;
#override
Widget build(BuildContext context) {
User user = Provider.of<User>(context);
String handle = '';
print(user.uid);
Future<String> str = databaseMethods.retrieveData(user.uid);
str.then((value) => {
handle = value
});
print(handle);
return new Scaffold(
// appBar: AppBar(
// title:
// ),
body: Container(
padding: EdgeInsets.symmetric(vertical: 20, horizontal: 50),
child: Form(
key: formKey, // keep track of form and its state
child : Column (
children: <Widget>[
Image.asset('assets/profilepicture.png', height: 300, width: 300),
SizedBox(height: 20),
TextFormField(
decoration: InputDecoration(
hintText: 'Name',
icon: Icon(Icons.person_outline, color: Colors.blue),
fillColor: Colors.white,
filled: true,
enabledBorder: OutlineInputBorder(
borderSide: BorderSide(color: Colors.grey[300], width: 2),
),
focusedBorder: OutlineInputBorder(
borderSide: BorderSide(color: Colors.blue, width: 2),
)
),
validator: (val) => val.isEmpty ? 'Enter your name' : null,
onChanged: (val) {
setState(() => name = val);
},
),
SizedBox(height: 20),
TextFormField(
decoration: InputDecoration(
hintText: 'Handle',
icon: Icon(Icons.alternate_email, color: Colors.blue),
fillColor: Colors.white,
filled: true,
enabledBorder: OutlineInputBorder(
borderSide: BorderSide(color: Colors.grey[300], width: 2),
),
focusedBorder: OutlineInputBorder(
borderSide: BorderSide(color: Colors.blue, width: 2),
)
),
obscureText: false,
validator: (val) => val[0] != '#' ? 'Handle starts with #!' : null,
onChanged: (val) {
setState(() => handle = val);
},
),
SizedBox(height: 20),
Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: <Widget> [
RaisedButton(
color: Colors.blueAccent,
child: Text(
'Update',
style: TextStyle(color: Colors.white),
),
onPressed: () async {
if(formKey.currentState.validate()) {
print(user.uid);
await databaseMethods.updateSpecificUserData(user.uid, name, handle);
setState(() {
error = 'Update successful!';
});
}
},
),
],
),
SizedBox(height: 12),
Text(
error,
style: TextStyle(color: Colors.black, fontSize: 16),
)
],
),
),
),
);
}
}
My code can be real messy (for which I apologise because I have been stuck on this for a quite long time and have been rigorously attempting various methods to extract the data out).
Ultimately, my main objective is to get the value(handle) from my data stored in firebase and then to dynamically display it on my appbar.
My firebase database collection is named 'users' and carries only data { name: "...", handle: "..."}.
Thanks for bearing with my long post.
Profile page

Answer 1

Here is how you can get data from firebase's firestore. I think its best to rename your "name" as "n" to make the size of your data stored in the database smaller.
await Firestore.instance
.collection('users')
.document(uid)
.get()
.then((DocumentSnapshot ds) {
username = ds["name"];
});