How to fix this error:
Undefined string name
In line 64 I have defined the string name but in line 117 the string name is undefined and if I try to make it defined there come's an other error in line 60: The body might complete normally, causing 'null' to be returned, but the return type, 'Widget', is a potentially non-nullable type and if I fix this I get an black screen.
So in short can anyone help me with this error without getting other errors.
import 'dart:async';
import 'dart:io';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_svg/flutter_svg.dart';
import 'package:flutter_svg/svg.dart';
import 'package:hetmaantje/arbo.dart';
import 'package:hetmaantje/inschrijven.dart';
import 'package:hetmaantje/quiz_screen.dart';
import 'package:hetmaantje/utils1/colors.dart';
import 'package:hetmaantje/todolist.dart';
import 'package:page_transition/page_transition.dart';
import 'package:path_provider/path_provider.dart';
import 'contactpage.dart';
class home extends StatefulWidget {
const home({Key? key}) : super(key: key);
@override
State<home> createState() => _homeState();
}
class _homeState extends State<home> {
String pathPDF = "assets/arbo";
@override
void initState() {
super.initState();
fromAsset('assets/arbo.pdf', 'arbo.pdf').then((f) {
setState(() {
pathPDF = f.path;
});
});
}
Future<File> fromAsset(String asset, String filename) async {
Completer<File> completer = Completer();
try {
var dir = await getApplicationDocumentsDirectory();
File file = File("${dir.path}/$filename");
var data = await rootBundle.load(asset);
var bytes = data.buffer.asUint8List();
await file.writeAsBytes(bytes, flush: true);
completer.complete(file);
} catch (e) {
throw Exception('Error parsing asset file!');
}
return completer.future;
}
final FirebaseAuth auth = FirebaseAuth.instance;
late final User? user = auth.currentUser;
late final uid = user?.uid;
Widget build(BuildContext context) {
DocumentReference documentReference = FirebaseFirestore.instance.collection(uid!).doc("name");
documentReference.get().then((datasnapshot){
String name = datasnapshot.data().toString();
});
FirebaseFirestore.instance.collection(uid!);
// to get size
var size = MediaQuery.of(context).size;
// style
var cardTextStyle = TextStyle(
fontFamily: "Montserrat Regular",
fontSize: 14,
color: Color.fromRGBO(63, 63, 63, 1));
return Scaffold(
body: Stack(
children: <Widget>[
Container(
height: size.height * 1,
decoration: BoxDecoration (gradient: LinearGradient(colors: [
hexStringToColor("FFBEC8"),
hexStringToColor("fe98a8"),
hexStringToColor("FC98A7"),
hexStringToColor("#FF8799")
]
))),
SafeArea(
child: Padding(
padding: EdgeInsets.all(16.0),
child: Column(
children: <Widget>[
Container(
height: 64,
margin: EdgeInsets.only(bottom: 20),
child: Row(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
CircleAvatar(
radius: 29,
backgroundImage: AssetImage(
'assets/logo.png'),
),
SizedBox(
width: 16,
),
Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Text(
"$name",
style: TextStyle(
fontFamily: "Montserrat Medium",
color: Colors.white,
fontSize: 20),
),
],
)
],
),
),
Expanded(
child: GridView.count(
mainAxisSpacing: 10,
crossAxisSpacing: 10,
primary: false,
crossAxisCount: 2,
children: <Widget>[
Card(
color: Colors.grey.shade100,
shape:RoundedRectangleBorder(
borderRadius: BorderRadius.circular(8)
),
elevation: 4,
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
//=> PDFScreen(path: pathPDF)),);
children: <Widget>[
GestureDetector(
onTap:
() =>
Navigator.of(context).push(PageTransition(
child: PDFScreen(path: pathPDF),
type: PageTransitionType.fade)),
child:
SvgPicture.asset(
'assets/moon.svg',
height: 120,
)
),
Text(
'Arbo-lijst',
style: cardTextStyle,
)
],
),
),
Card(
color: Colors.grey.shade100,
shape:RoundedRectangleBorder(
borderRadius: BorderRadius.circular(8)
),
elevation: 4,
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
GestureDetector(
onTap:
() =>
Navigator.of(context).push(PageTransition(
child: todolist(),
type: PageTransitionType.fade)),
child:
SvgPicture.asset(
'assets/moon.svg',
height: 120,
)
),
Text(
"To do lijst",
style: cardTextStyle,
)
],
),
),
Card(
color: Colors.grey.shade100,
shape:RoundedRectangleBorder(
borderRadius: BorderRadius.circular(8)
),
elevation: 4,
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
GestureDetector(
onTap:
() =>
Navigator.of(context).push(PageTransition(
child: home(),
type: PageTransitionType.fade)),
child:
SvgPicture.asset(
'assets/moon.svg',
height: 120,
)
),
Text(
'Uitzetlijst',
style: cardTextStyle,
)
],
),
),
Card(
color: Colors.grey.shade100,
shape:RoundedRectangleBorder(
borderRadius: BorderRadius.circular(8)
),
elevation: 4,
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
GestureDetector(
onTap:
() =>
Navigator.of(context).push(PageTransition(
child: inschrijven(),
type: PageTransitionType.fade)),
child:
SvgPicture.asset(
'assets/moon.svg',
height: 120,
)
),
Text(
'Inschrijven',
style: cardTextStyle,
)
],
),
),
Card(
color: Colors.grey.shade100,
shape:RoundedRectangleBorder(
borderRadius: BorderRadius.circular(8)
),
elevation: 4,
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
GestureDetector(
onTap:
() =>
Navigator.of(context).push(PageTransition(
child: home(),
type: PageTransitionType.fade)),
child:
SvgPicture.asset(
'assets/moon.svg',
height: 120,
)
),
Text(
'Opstart advies',
style: cardTextStyle,
)
],
),
),
Card(
color: Colors.grey.shade100,
shape:RoundedRectangleBorder(
borderRadius: BorderRadius.circular(8)
),
elevation: 4,
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
GestureDetector(
onTap:
() =>
Navigator.of(context).push(PageTransition(
child: contactpage(),
type: PageTransitionType.fade)),
child:
SvgPicture.asset(
'assets/moon.svg',
height: 120,
)
),
Text(
'Contact',
style: cardTextStyle,
)
],
),
),
Card(
color: Colors.grey.shade100,
shape:RoundedRectangleBorder(
borderRadius: BorderRadius.circular(8)
),
elevation: 4,
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
GestureDetector(
onTap:
() =>
Navigator.of(context).push(PageTransition(
child: quiz_screen(),
type: PageTransitionType.fade)),
child:
SvgPicture.asset(
'assets/moon.svg',
height: 120,
)
),
Text(
'Quiz',
style: cardTextStyle,
)
],
),
),
Card(
color: Colors.grey.shade100,
shape:RoundedRectangleBorder(
borderRadius: BorderRadius.circular(8)
),
elevation: 4,
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
GestureDetector(
onTap:
() =>
Navigator.of(context).push(PageTransition(
child: home(),
type: PageTransitionType.fade)),
child:
SvgPicture.asset(
'assets/moon.svg',
height: 120,
)
),
Text(
'Kaart',
style: cardTextStyle,
)
],
),
),
],
),
),
],
),
),
),
],
),
);
}
}
CodePudding user response：
You need define name out of build method to access it in all your class:
String name = ''; //<-- define this
Widget build(BuildContext context) {
DocumentReference documentReference = FirebaseFirestore.instance.collection(uid!).doc("name");
documentReference.get().then((datasnapshot){
name = datasnapshot.data().toString();//<-- change this
});
...
}