I'm new into flutter and firebase integrations and I'm having some troubles to retreive all the data from the firebase collection.
I have tried this method:
getCollection() {
CollectionReference coleccion =
FirebaseFirestore.instance.collection('materias');
return Container(
child: StreamBuilder(
stream: coleccion.doc('aprobadas').snapshots(),
builder: (BuildContext context, AsyncSnapshot snapshot) {
if (snapshot.connectionState == ConnectionState.active) {
return Text(snapshot.data.data()['codigo'],
style: TextStyle(fontSize: 50, color: Colors.white));
} else {
return CircularProgressIndicator();
}
},
),
);
}
Now I'm a little bit frustrated because I have tried a differents methods and doesn't work.
I really appreciate all the help.
Best regards
Data can be retrieved using the below code from firestore to flutter.
One-time Read
call the Query.get or DocumentReference.get methods
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() as Map<String, dynamic>;
return Text("Full Name: ${data['full_name']} ${data['last_name']}");
}
return Text("loading");
},
);
}
}
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();
Please refer official documentation here
You can use a StreamBuilder. That will be easy to understand.
StreamBuilder(
stream: FirebaseFirestore.instance.collection("collection").snapshot,
builder: (BuildContext context,snapshot) {
if(snapshot.hasdata!=true) {
return CircularProgressIndicator();
} else {
return ListView.builder(
itemcount:snapshot.data.docs.length,
builder(context,index) {
return Text(snapshot.data.docs[index].data()["filedname"]);
}
}
)
Related
I m trying to snapshot the Collection of users and I want to check if the user has the field or not
If the users has then show this
If user doesn’t have then show this
This is the code i got so far.
class _HalfScreenState extends State<HalfScreen> {
final userUid = FirebaseAuth.instance.currentUser!.uid;
#override
Widget build(BuildContext context) {
return StreamBuilder<DocumentSnapshot?>(
stream: FirebaseFirestore.instance
.collection("users")
.doc(userUid)
.snapshots(),
builder: (context, snapshot) {
if (snapshot.data != null) {
return const Text("Loading...");
}
return Text(
(snapshot.data as DocumentSnapshot)['groupId'],
),
});
}
}
Step by step that'd be:
Get the data from the document as a Map.
Check if the map contains a key for the field you're looking for.
In code that'd be something like this:
// 👇 Indicate the type of the data in the document
return StreamBuilder<DocumentSnapshot<Map<String, dynamic>>>(
stream: FirebaseFirestore.instance
.collection("users")
.doc(userUid)
.snapshots(),
builder: (context, snapshot) {
if (snapshot.data != null) {
return const Text("Loading...");
}
// 👇 Get the data (Map<String, dynamic>
var data = snapshot.data.data();
return Text(
// 👇 Check if the field is tere
data.containsKey('groupId') ? 'Yes, it's there' : 'Nope, field not found'
),
}
);
I am trying to retrieve data from my Firestore database via a Streambuilder. The issue I have comes from an error from the following error when I add my doc(uid) into my _usersStream:
A value of type 'Stream<DocumentSnapshot<Map<String, dynamic>>>' can't be assigned to a variable of type 'Stream<QuerySnapshot<Object?>>'.
Try changing the type of the variable, or casting the right-hand type to 'Stream<QuerySnapshot<Object?>>'.
I was wondering how to how to rectify this error. Here is my code:
class _UserProfileScreenState extends State<UserProfileScreen> {
final Stream<QuerySnapshot> _usersStream = FirebaseFirestore.instance.collection('users').doc(uid).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("");
}
return Scaffold(
appBar: ProfileAppBar(),
body: ListView(
children: snapshot.data!.docs.map((DocumentSnapshot document) {
Map<String, dynamic> data =
document.data()! as Map<String, dynamic>;
return ListTile(
title: Text(data['username']),
subtitle: Text(data['displayName']),
);
}).toList(),
),
);
},
);
}
}
There is some issue when you define _userStream
final Stream<QuerySnapshot> _usersStream = FirebaseFirestore.instance.collection('users').doc(uid).snapshots();
_userStream is a value of type Stream<DocumentSnapshot<Map<String, dynamic>>>
_userStream should be like this.
final Stream<DocumentSnapshot<Map<String, dynamic>>> _usersStream = FirebaseFirestore.instance.collection('users').doc(uid).snapshots();
it is better to use FutureBuilder
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() as Map<String, dynamic>;
return Text("Full Name: ${data['full_name']} ${data['last_name']}");
}
return Text("loading");
},
);
}
}
Please check this guide
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(
},
);
}
}
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)
I need a field in firebase which is their stored:
FirebaseFirestore.instance.collection("comments").doc(IdFromPost).collection(firebaseUser1.uid)
.add({"comment" : messageEditingController.text});
does anyone know how I can display the field "comment" ?
From reading the FlutterFire documentation on reading data, that should be something like:
#override
Widget build(BuildContext context) {
CollectionReference comments = FirebaseFirestore.instance.collection('comments');
return FutureBuilder<DocumentSnapshot>(
future: comments.doc(IdFromPost).get(),
builder:
(BuildContext context, AsyncSnapshot<DocumentSnapshot> snapshot) {
if (snapshot.hasError) {
return Text("Something went wrong");
}
if (snapshot.connectionState == ConnectionState.done) {
Map<String, dynamic> data = snapshot.data.data();
return Text(data['comment']);
}
return Text("loading");
},
);
}
}
I am building a Flutter application and I am having trouble understanding how to implement Firestore. Out of the tutorials I have seen, I only see how to create a snapshot of an entire collection, however in my case, my collection is users, so I only need to snapshot the document of a particular user. There doesn't appear to be documentation on the Firebase docs on how to do this nor is there much documentation on the FlutterFire GitHub page. Please help!
This is the Widget I'm trying to build with StreamBuilder.
#override
Widget build(BuildContext context) {
return new StreamBuilder(
stream: Firestore.instance.collection('users').document(userId).snapshots(),
builder: (context, snapshot) {
return new ListView.builder(
itemCount: //what do I put here?,
itemBuilder: (context, index) => new Item(//And here?),
);
}
);
}
Lets say you want to create a Text with the name parameter from your document
Widget build(BuildContext context) {
String userId = "skdjfkasjdkfja";
return StreamBuilder(
stream: Firestore.instance.collection('users').document(userId).snapshots(),
builder: (context, AsyncSnapshot<DocumentSnapshot> snapshot) {
if (!snapshot.hasData) {
return Text("Loading");
}
var userDocument = snapshot.data;
return Text(userDocument["name"]);
}
);
}
This is just one instance. Creating a StreamBuilder on the document will rebuild itself every time the document itself is changed. You can try this code, and then go to your console and change the "name" value. Your app will automatically reflect the changes.
Instead of just one Text, you could build entire tree that uses data from your stream.
If you want to get just at the moment value of the document, you can do so by resolving the Future of get() method on document reference.
var document = await Firestore.instance.collection('users').document(userId).get(),
Each element should be casted to have a reference later in the code.
return new StreamBuilder<DocumentSnapshot>(
stream: Firestore.instance.collection('users').document(userId).snapshots(), //returns a Stream<DocumentSnapshot>
builder: (BuildContext context, AsyncSnapshot<DocumentSnapshot> snapshot) {
if (!snapshot.hasData) {
return new Text("Loading");
}
var userDocument = snapshot.data;
return new Text(userDocument["name"]);
}
);
}
Update 2023 with null safety
class _UserInformationState extends State<UserInformation> {
final _usersStream = FirebaseFirestore.instance
.collection('users')
.doc(FirebaseAuth.instance.currentUser!.uid) // 👈 Your document id change accordingly
.snapshots();
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: StreamBuilder<DocumentSnapshot<Map<String, dynamic>>>(
stream: _usersStream,
builder:
(BuildContext context, AsyncSnapshot<DocumentSnapshot> snapshot) {
if (snapshot.hasError) {
return const Text('Something went wrong');
}
if (snapshot.connectionState == ConnectionState.waiting) {
return const Text("Loading");
}
Map<String, dynamic> data =
snapshot.data!.data()! as Map<String, dynamic>;
return Text(data['fullName']);
},
),
),
);
}
}