CODEWITHSUNDEEP
flutterfirebasedartgoogle-cloud-firestore
ihatecoding
ihatecoding

Reputation: 106

Get one field from one document in Firestore

I want the username from the current logged in user in my flutter app.

This is what I have currently.

Future<String> get username async {
await FirebaseFirestore.instance
    .collection('users')
    .doc(user.uid)
    .get()
    .then((snapshot) {
  if (snapshot.exists) {
    return snapshot.data()!['username'].toString();
  }
});
return 'No User';
}

It's giving me "Instance of 'Future<String>'.

Upvotes: 1

Views: 1050

Answers (3)

Sana
Sana

Reputation: 151

Future<String> get username         
async {
    await FirebaseFirestore.instance
    .collection('users')
    .doc(user.uid)
    .get()
    .then((snapshot) {
        if (snapshot.exists) { 
            _user = snapshot.data['username'].toString();         
            return _user    
}    
});
    return 'No User';
}

Upvotes: 1

ihatecoding
ihatecoding

Reputation: 106

Figured it out... ended up using this.

FutureBuilder<DocumentSnapshot<Map<String, dynamic>>>(
                  future: FirebaseFirestore.instance
                      .collection('users')
                      .doc(user.uid)
                      .get(),
                  builder: (_, snapshot) {
                    if (snapshot.hasData) {
                      var data = snapshot.data!.data();
                      var value = data!['username'];
                      return Text(value);
                    }
                    return const Text('User');
                  },
                ),

Upvotes: 2

Frank van Puffelen
Frank van Puffelen

Reputation: 598765

That is expected. Since you're using an asynchronous operation inside he getter implementation and that takes time to complete, there is no way for it to return the string value right away. And since it's not possible to block the execution of the code (that would lead to a horrible user experience), all it can return now is Future<String>: an object that may result in a string at some point.

To get the value from a Future, you can either use then or await. The latter is easiest to read and would be:

print(await username);

With then() it's look like this:

username.then((value) {
  print(value); 
})

To learn more about dealing with asynchronous behavior in Flutter/Dart, check out Asynchronous programming: futures, async, await.

Upvotes: 1

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