When trying to open this screen I get the message, "Field 'snapshot' has not been initialized." Pretty sure it's something to do with the "snapshot" being a late, but I don't know how to change it to make it work. This is an error when tying to open the page, not when building app. Any Help would be Appreciated!
class Upload extends StatefulWidget {
@override
_UploadState createState() => _UploadState();
}
class _UploadState extends State<Upload> {
// ignore: cancel_subscriptions
late StreamSubscription<QuerySnapshot> subscription;
late List<DocumentSnapshot> snapshot;
CollectionReference collectionReference =
FirebaseFirestore.instance.collection('NewsPost');
@override
void initState() {
super.initState();
subscription = collectionReference.snapshots().listen((dataSnapshot) {
setState(() {
snapshot = dataSnapshot.docs;
});
});
}
// TODO Pass Data Method
passData(DocumentSnapshot snap) {
Navigator.of(context).push(
MaterialPageRoute(builder: (context) => PostDetails(snapshot: snap)));
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Flutter Blog App'),
backgroundColor: Colors.redAccent,
actions: [
IconButton(
icon: Icon(Icons.search),
onPressed: () => debugPrint('search'),
),
IconButton(
icon: Icon(Icons.add),
onPressed: () => debugPrint('add'),
)
],
),
drawer: Drawer(
child: ListView(
children: [
UserAccountsDrawerHeader(
decoration: BoxDecoration(
gradient: LinearGradient(
colors: [Colors.purpleAccent, Colors.redAccent]),
),
accountName: Text('Ahmer Iqbal'),
accountEmail: Text('[email protected]'),
currentAccountPicture: CircleAvatar(
child: Text('A'),
backgroundColor: Colors.white,
),
),
ListTile(
leading: Icon(Icons.cake, color: Colors.purple),
title: Text('First Page'),
),
ListTile(
leading: Icon(Icons.search, color: Colors.redAccent),
title: Text('Second Page'),
),
ListTile(
leading: Icon(Icons.cached, color: Colors.orange),
title: Text('Third Page'),
),
ListTile(
leading: Icon(Icons.menu, color: Colors.green),
title: Text('Fourth Page'),
),
Divider(height: 10.0, color: Colors.black),
ListTile(
trailing: Icon(Icons.close, color: Colors.red),
title: Text('Close'),
onTap: () {
Navigator.of(context).pop();
},
),
],
),
),
body: snapshot == null
? Container(
alignment: Alignment.center,
child: CircularProgressIndicator(),
)
: ListView.builder(
itemCount: snapshot.length,
itemBuilder: (context, index) {
return Card(
elevation: 10.0,
margin: EdgeInsets.all(10.0),
child: Container(
padding: EdgeInsets.all(10.0),
child: Row(
mainAxisAlignment: MainAxisAlignment.start,
children: [
CircleAvatar(
child: Text(snapshot[index].get('title')[0]),
backgroundColor: Colors.redAccent,
foregroundColor: Colors.white,
),
SizedBox(width: 10.0),
Container(
width: 210.0,
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
InkWell(
child: Text(
snapshot[index].get('title'),
maxLines: 1,
style: TextStyle(
fontSize: 22.0,
color: Colors.green,
),
),
onTap: () {
// pass each and every index data
passData(snapshot[index]);
},
),
SizedBox(height: 5.0),
Text(
snapshot[index].get('content'),
maxLines: 2,
)
],
),
),
],
),
),
);
},
),
);
}
}
import 'package:iona_central/Screens/Admin/updatedescription.dart';
import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'dart:async';
class Upload extends StatefulWidget {
@override
_UploadState createState() => _UploadState();
}
class _UploadState extends State<Upload> {
// ignore: cancel_subscriptions
late StreamSubscription<QuerySnapshot> subscription;
late List<DocumentSnapshot> snapshot;
CollectionReference collectionReference =
FirebaseFirestore.instance.collection('NewsPost');
@override
void initState() {
super.initState();
subscription = collectionReference.snapshots().listen((dataSnapshot) {
setState(() {
snapshot = dataSnapshot.docs;
});
});
}
// TODO Pass Data Method
passData(DocumentSnapshot snap) {
Navigator.of(context).push(
MaterialPageRoute(builder: (context) => PostDetails(snapshot: snap)));
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Flutter Blog App'),
backgroundColor: Colors.redAccent,
actions: [
IconButton(
icon: Icon(Icons.search),
onPressed: () => debugPrint('search'),
),
IconButton(
icon: Icon(Icons.add),
onPressed: () => debugPrint('add'),
)
],
),
drawer: Drawer(
child: ListView(
children: [
UserAccountsDrawerHeader(
decoration: BoxDecoration(
gradient: LinearGradient(
colors: [Colors.purpleAccent, Colors.redAccent]),
),
accountName: Text('Ahmer Iqbal'),
accountEmail: Text('[email protected]'),
currentAccountPicture: CircleAvatar(
child: Text('A'),
backgroundColor: Colors.white,
),
),
ListTile(
leading: Icon(Icons.cake, color: Colors.purple),
title: Text('First Page'),
),
ListTile(
leading: Icon(Icons.search, color: Colors.redAccent),
title: Text('Second Page'),
),
ListTile(
leading: Icon(Icons.cached, color: Colors.orange),
title: Text('Third Page'),
),
ListTile(
leading: Icon(Icons.menu, color: Colors.green),
title: Text('Fourth Page'),
),
Divider(height: 10.0, color: Colors.black),
ListTile(
trailing: Icon(Icons.close, color: Colors.red),
title: Text('Close'),
onTap: () {
Navigator.of(context).pop();
},
),
],
),
),
body: snapshot == null
? Container(
alignment: Alignment.center,
child: CircularProgressIndicator(),
)
: ListView.builder(
itemCount: snapshot.length,
itemBuilder: (context, index) {
return Card(
elevation: 10.0,
margin: EdgeInsets.all(10.0),
child: Container(
padding: EdgeInsets.all(10.0),
child: Row(
mainAxisAlignment: MainAxisAlignment.start,
children: [
CircleAvatar(
child: Text(snapshot[index].get('title')[0]),
backgroundColor: Colors.redAccent,
foregroundColor: Colors.white,
),
SizedBox(width: 10.0),
Container(
width: 210.0,
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
InkWell(
child: Text(
snapshot[index].get('title'),
maxLines: 1,
style: TextStyle(
fontSize: 22.0,
color: Colors.green,
),
),
onTap: () {
// pass each and every index data
passData(snapshot[index]);
},
),
SizedBox(height: 5.0),
Text(
snapshot[index].get('content'),
maxLines: 2,
)
],
),
),
],
),
),
);
},
),
);
}
}
Let me know if you need to see updatedesctription.dart aswell!
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CodePudding user response：
snapshot wasn't defined to be a nullable value so snapshot==null won't work.
Define it as a nullable like so:
Change late List<DocumentSnapshot> snapshot;
to
List<DocumentSnapshot>? snapshot;