Why is the data I pulled from firebase coming from null? - firebase

Question

Patients model dart file;
import 'package:flutter/material.dart';
class Patients {
String patientId;
String nurseId;
String username;
DateTime date;
int age;
List<String> diseases;
//final fotograf olacak
Patients({#required this.patientId,this.nurseId,this.date,this.username,this.age,this.diseases});
factory Patients.fromJson(Map<String, dynamic> json){
return Patients(
patientId: json["patientId"],
nurseId: json["nurseId"],
username: json["username"],
date: json["date"],
age: json["age"],
diseases: json["diseases"],
);
}
Map<String,dynamic> toMap(){
return {
"patientId": patientId,
"nurseId" : nurseId,
"username" : username,
"date" : date,
"age" : age,
"diseases" : diseases,
};
}
}
PatientsProvider dart file;
import 'package:flutter/material.dart';
import 'package:imlearningfirebase/model/patients.dart';
import 'package:uuid/uuid.dart';
import 'package:imlearningfirebase/services/fireStoreService.dart';
class PatientsProvider with ChangeNotifier{
final fireStoreService = FireStoreService();
String _patientId;
String _nurseId;
DateTime _date;
String _username;
int _age;
List<String> _diseases;
var uuid = Uuid();
///Getters
String get username =>_username;
int get age => _age;
List<String> get diseases => _diseases;
DateTime get date => _date;
Stream<List<Patients>> get getPatients => fireStoreService.getEntries();
savePatient(int agee,String usernamee,List<String> diseasess){
if(_nurseId == null){
///add
var newPatient = Patients(patientId: uuid.v1(),nurseId:fireStoreService.getCurrentUserId().toString(),date:DateTime.now(),username: usernamee,age: agee,diseases: diseasess);
print(newPatient.username);
fireStoreService.setPatients(newPatient);
}else{
var updatedPatients = Patients(patientId: uuid.v1(),nurseId:fireStoreService.getCurrentUserId().toString(),date:DateTime.now(),username: usernamee,age: agee,diseases: diseasess);
fireStoreService.setPatients(updatedPatients);
}
}
}
FireStoreService dart file;
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
/// Local Importlar
import '../model/patients.dart';
class FireStoreService{
FirebaseFirestore _db = FirebaseFirestore.instance;
final FirebaseAuth auth = FirebaseAuth.instance;
///Get Entries
Stream<List<Patients>> getEntries(){
return _db
.collection("patients")
.snapshots()
.map((snapshot) => snapshot.docs
.map((doc) => Patients.fromJson(doc.data()))
.toList());
}}
Home screen;
import 'package:flutter/material.dart';
import 'package:imlearningfirebase/provider/patienstProvider.dart';
import 'package:provider/provider.dart';
class HomePage extends StatelessWidget{
#override
Widget build(BuildContext context) {
final patientsProvider = Provider.of<PatientsProvider>(context);
return Scaffold(
appBar: AppBar(
title: Text("Patients"),
),
floatingActionButton: Padding(
padding: const EdgeInsets.fromLTRB(0, 0, 0, 50.0),
child: FloatingActionButton(
onPressed: () async {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => AddPatient()),
);
},
child: Icon(
Icons.add,
color: Colors.blueAccent,
),
backgroundColor: Colors.green,
),
),
body:StreamBuilder<List<Patients>>(
stream: patientsProvider.getPatients,
builder: (context,snapshot){
return ListView.builder(
itemCount: snapshot.data.length,
itemBuilder: (context,index){
return ListTile(
trailing:
Icon(Icons.edit, color: Theme.of(context).accentColor),
title: Text('${DateTime.now()}'
),
);
}
);
}
)
);
}
}
I am trying to create a system where a person has to register and register another person. I created a model so that the registered person creates the profile of the other person. The name of this model is patients. I use the provider package to access patients functions. I have created a function named take patients in Firestore and put it in the patient provider. Finally, I call this on the Home page. but the length came null. I can not see the error I would be glad if you help.

Answer 1

I didn't use your FireStoreService() class. This might be a bit messy but it worked for me. let me know if it works.
Try this:
class PatientsProvider with ChangeNotifier {
...
List<Patients> _patients = [];
// ///Getters
...
// Stream<List<Patients>> get getPatients => fireStoreService.getEntries();
List<Patients> get getPatients => _patients;
FirebaseFirestore _fs = FirebaseFirestore.instance;
StreamSubscription<QuerySnapshot> _stream;
PatientsProvider() {
_stream = _fs.collection('patients').snapshots().listen((snapshot) {
_patients = [];
snapshot.docs.forEach((queryDocumentSnapshot) {
_patients.add(Patients.fromJson(queryDocumentSnapshot.data()));
});
notifyListeners();
});
}
#override
void dispose() {
super.dispose();
_stream.cancel();
}
// savePatient(int agee, String usernamee, List<String> diseasess) {
...
// }
}
Then instead if creating a streambuilder, the provider will update the list when the data changes:
#override
Widget build(BuildContext context) {
PatientsProvider _provider = Provider.of<PatientsProvider >(context);
return Scaffold(
body: ListView.builder(
itemCount: _provider.getPatients.length,
itemBuilder: (BuildContext context, int index) {
return ListTile(
trailing: Icon(Icons.edit, color: Theme.of(context).accentColor),
title: Text('${...}'),
);
},
),
);
}
To get more information on the listener see this documentation:
https://firebase.google.com/docs/firestore/query-data/listen