I have created a group screen in my flutter app and when I hit the create button it create a group as described is code:
//Create group
Future<String> createGroup(String groupName1, userUid) async {
String retVal = "error";
List<String> members = [];
try {
members.add(userUid);
DocumentReference docRef;
docRef = await firestore.collection("groups").add({
'name': groupName1,
'leader': userUid,
'members': members,
'groupCreate': Timestamp.now(),
});
retVal = "success";
} catch (e) {
// ignore: avoid_print
print(e);
}
return retVal;
}
I am stuck in getting the snapshot from my FBbackend. I want to get the info and display is on my group screen. How can I achieve that?
I have try to get the snapshot but it says Text("..."). I think the problem is that the value of DocumentReference? docRef; is empty, but I don’t know how to fixed it.
code:
DocumentReference? docRef;
docRef == null
? const Text('Error No Group Name Found!!')
: // 👈 handle null here
StreamBuilder<DocumentSnapshot<Map<String, dynamic>>>(
stream: FirebaseFirestore.instance
.collection('groups')
.doc(docRef!.id)
.snapshots(),
builder: (context, snapshot) {
if (snapshot.data == null) {
return const ErrorScreen();
}
return Center(
child: Text((snapshot.data
as DocumentSnapshot<
Map<String, dynamic>>)['name']),
);
}),
Related
My goal:
I want to retrieve a list of documents from the Firebase Firestore using a Stream to update the interface in real time when the Firestore data changes.
The problem:
I am able to download the data from Firestore with the structure I need, but when I make changes in firestore the interface does not update in real time. When I reload the page, it updates, but that is not the behavior I need.
This is the Stream I have created:
Stream<DayModel> getInstances(String selectedDay, String userUid) async* {
DayModel retval = DayModel();
List<InstanceModel> instances = [];
int index = 0;
try {
final QuerySnapshot<Map<String, dynamic>> querySnapshot =
await FirebaseFirestore.instance
.collection('instances')
.doc(selectedDay)
.collection('instancesUid')
.where("instanceUsersUid", arrayContains: userUid)
.get();
instances = querySnapshot.docs
.map((instance) => InstanceModel.fromSnapshot(instance))
.toList();
for (InstanceModel instance in instances) {
final DocumentSnapshot<Map<String, dynamic>> instanceQuery =
await FirebaseFirestore.instance
.collection('instances')
.doc(selectedDay)
.collection('instancesUid')
.doc(instance.uid)
.get();
instance = InstanceModel.fromMap(instanceQuery);
instances[index] = instance;
index++;
}
retval.instances = instances;
yield retval;
} on Exception catch (e) {
print(e);
}
}
StreamBuilder code:
body: StreamBuilder<DayModel>(
stream:
OurDatabase().getInstances(selectedDay, _currentUser!.uid!),
builder:
(BuildContext context, AsyncSnapshot<DayModel> snapshot) {
if (snapshot.hasError) {
return Center(child: CircularProgressIndicator());
}
if (snapshot.connectionState == ConnectionState.waiting) {
return Center(
child: CircularProgressIndicator(),
);
}
return Center(
child: snapshot.data!.instances!.isNotEmpty
? Text(snapshot.data!.instances![0].uid!)
: Text('No tienes instancias!'),
);
})
Maybe it's because I'm not returning the Stream with a QuerySnapshot?
I have read in other similar posts that it could be a problem with the keys, but I have tried several different combinations and it has not worked.
Do you have any idea what could be happening?
Thank you for your time.
I am trying to read the data from a list that has the data of Instance of '_JsonQuerySnapshot'.
In the below code I am trying to get the data from DB
getData() async {
var db = FirebaseFirestore.instance;
var categoryList = [];
db.collection('categories')
.doc(value)
.get()
.then((DocumentSnapshot doc) {
var listSubCol = doc["categoryCollection"];
listSubCol.forEach((id) {
db.collection('categories')
.doc(value)
.collection(id)
.get()
.then((snapshot) {
categoryList.add(snapshot);
return categoryList;
});
});
});
}
Below is the code where I am printing the values.
FutureBuilder(
future: getData(),
builder: (BuildContext context, snapshot){
if (snapshot.hasError) {
return Text("Something went wrong");
}
if (snapshot.connectionState == ConnectionState.done) {
print('Data: ${snapshot.data}');
return Text("Text");
}
return Text("Text Outside");
}
)
I got a null value.
Can anyone please help me with how to get the data?
The getData is a Future<void>, so when the FutureBuilder is completed the snapshot.data is always null.
Change getData to return a List of whatever you are getting.
Future<List<Categories>> getData() async {
var db = FirebaseFirestore.instance;
final List<Categories> categoryList = [];
await db.collection('categories')
.doc(value)
.get()
.then((DocumentSnapshot doc) {
var listSubCol = doc["categoryCollection"];
listSubCol.forEach((id) {
db.collection('categories')
.doc(value)
.collection(id)
.get()
.then((snapshot) {
categoryList.add(snapshot);
return categoryList;
});
});
});
return categoryList;
}
getData() async {
var db = FirebaseFirestore.instance;
await db.collection('categories').doc(value).get().then((DocumentSnapshot doc) {
var listSubCol = doc["categoryCollection"];
listSubCol.forEach((id) {
db.collection('categories').doc(value).collection(id).get().then((snapshot) {
snapshot.docs.forEach((element) {
categoryList.add(element.data());
});
});
return categoryList;
});
});
return categoryList;
}
using the above method i got the data from Firestore.
I want to get List values as ints one by one.
where movieId requires an int value.
help me please
thank you
Future<MovieDetailModel> getMovieDetail(int? movieId) async {
try {
http.Response res = await http
.get(Uri.parse('$mainUrl/movie/$**movieId**?$apiKey&language=ko-KR'))
.timeout(Duration(seconds: 8),
onTimeout: () async => new http.Response('{}', 404));
if (res.statusCode == 404) {
return MovieDetailModel.fromJson({});
}
Map<String, dynamic> result = jsonDecode(res.body);
MovieDetailModel movies = MovieDetailModel.fromJson(result);
return movies;
} catch (e) {
print('MovieDetail $e');
}
return MovieDetailModel.fromJson({});
}
where user.userMovieId value is List .
Widget userMovie(UserModel user) {
return FutureBuilder(
future: this._movieDetailProvider.movies(**user.userMovieId!**),
builder:
(BuildContext context, AsyncSnapshot<MovieDetailModel> snapshot) {
if (snapshot.hasData) {}
Provider.
Future<MovieDetailModel> movies(int movieId) async {
MovieDetailModel movieList = await _movieRepo.getMovieDetail(movieId);
notifyListeners();
return movieList;
}
I currently have a list of documents that each contain an int value called plastics. Currently, the list only displays the documents in order by when it was added to the collection, but I want to be able to order the documents based on the int value within each one. I've looked around on the web and I've only found tutorials mostly on ordering timestamps. Is there any documentation or sources on this matter? Here is the code situation I'm working with:
Firstly, in my app users can join groups, and when they do so they bring along their name and int data which is then stored in documents for each user.
Future<String> joinGroup(String groupId, String userUid, String displayName,
String plastics) async {
String retVal = 'error';
List<String> members = List();
try {
members.add(displayName);
await _firestore.collection('Groups').doc(groupId).update({
'members': FieldValue.arrayUnion(members),
});
final uid = FirebaseAuth.instance.currentUser.uid;
await _firestore.collection('UserNames').doc(uid).update({
'groupId': groupId,
});
//Below me is the code for doing so
await _firestore
.collection("Groups")
.doc(groupId)
.collection("Members")
.doc(userUid)
.set({'displayName': displayName, 'plastics': plastics});
retVal = 'success';
} catch (e) {}
return retVal;
}
I then take that code access the documents and put them in a list.
#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(),
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!');
}
});
}
});
}
Is there a specific function needed so that the documents in the Member collection are listed based on the numerical value of the plastics?
You can use orderBy to sort your results.
FirebaseFirestore.instance
.collection('Groups')
.doc(groupId)
.collection('Members')
.orderBy('plastics', descending: true)
.get()
Future<Map> returnUserMap() async {
final FirebaseUser currentUser = await _auth.currentUser();
Map userMap = {
"UserName": currentUser.displayName,
"UserEmail": currentUser.email,
"UserUrl": currentUser.photoUrl
};
print("1");
print(userMap);
return userMap;
}
return value type is Instance of 'Future>'.
I want to get a UserName, how can I do it?
Your function returnUserMap() returns a Future<Map>. I suspect that the error you describe is not in the code snippet you copied.
Whenever the task to be performed may take some time, you will receive a future. You can wait for futures in an async function with await.
It is therefore recommended to use a so-called FutureBuilder in your build() function:
FutureBuilder<FirebaseUser>(
future: _auth.currentUser(),
builder: (BuildContext context, AsyncSnapshot snapshot) {
if (snapshot.hasData) {
final FirebaseUser user = snapshot.data;
if (user.displayName == null || user.displayName.isEmpty())
return text(currentUser.email); // display email if name isn't set
return text(currentUser.displayName);
}
if (snapshot.hasError) {
return text(snapshot.error);
}
return text('loading...');
},
),
If you want to have the displayName outside your build() function, the following code should do the job when you are inside of an async function:
final FirebaseUser user = await _auth.currentUser();
final String displayName = user.displayName;
print('the displayName of the current user is: $displayName');
And this code when you are in a normal function:
_auth.currentUser().then((FirebaseUser user) {
String displayName = user.displayName;
print('displayName: $displayName');
}).catchError((error) {
print('error: ' + error.toString());
});
I think it's worth watching the following video for further understanding:
Async/Await - Flutter in Focus