Flutter Error: Another exception was thrown: Instance of 'DiagnosticsProperty' .It is showing a blank screen when redirected to that page.
I have successfully uploaded the text items , one image and one pdf to the firebase database and able to retrieve all of them in cards Widget view and List Tiles View Now I am trying to get individual view when clicked on List Items from List view.
Please check my code , I am seeing a blank screen when tried to redirect to the required Retrievepage.
RetrievePage.dart
import 'dart:async';
import 'dart:io';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:firebase_database/firebase_database.dart';
import 'package:flutter/material.dart';
import 'package:fluttertoast/fluttertoast.dart';
import 'package:gadjet_inventory/Form/ListTileFeed.dart';
import 'package:gadjet_inventory/Form/ListTiles.dart';
import 'package:gadjet_inventory/main.dart';
import 'package:intl/intl.dart';
import 'package:gadjet_inventory/Form/Data.dart';
import 'package:gadjet_inventory/Form/UploadData.dart';
import 'package:pdf_flutter/pdf_flutter.dart';
// ignore: must_be_immutable
import 'package:url_launcher/url_launcher.dart';
import 'Data.dart';
class RetrievePage extends StatefulWidget {
// String currentEmail;
//RetrievePage(this.currentEmail);
@override
_RetrievePageState createState() => _RetrievePageState();
}
class _RetrievePageState extends State<RetrievePage> {
List<Data> dataList = [];
List<bool> favList = [];
bool searchState = false;
FirebaseAuth auth = FirebaseAuth.instance;
@override
void initState() {
// TODO: implement initState
super.initState();
DatabaseReference referenceData = FirebaseDatabase.instance.reference().child("Data");
referenceData.once().then((DataSnapshot dataSnapShot) {
dataList.clear();
favList.clear();
var keys = dataSnapShot.value.keys;
var values = dataSnapShot.value;
for (var key in keys) {
Data data = new Data(
values [key]['imgUrl'],
values [key]['cattegorrytype'],
values [key]['companyname'],
values [key]['modelname'],
values [key]['seriesname'],
values [key]['serielnumber'],
values [key]['year'],
key
//key is the uploadid
);
dataList.add(data);
auth.currentUser().then((value) {
DatabaseReference reference = FirebaseDatabase.instance.reference().child("Data").child(key).child("Fav")
.child(value.uid).child("state");
reference.once().then((DataSnapshot snapShot){
if(snapShot.value!=null){
if(snapShot.value=="true"){
favList.add(true);
}else{
favList.add(false);
}
}else{
favList.add(false);
}
});
});
}
Timer(Duration(seconds: 1),(){
setState(() {
//
});
});
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(
"List View",
),
actions: <Widget>[
// action button
],
),
body: Center(
child: Container(
child: ListView.separated(
itemBuilder: (BuildContext context, int index) {
Column(
children: <Widget>[
Image.network(
dataList[index].imgUrl != null
? dataList[index].imgUrl
: '',
width: 500,
height: 500,
),
Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: <Widget>[
Expanded(
flex: 1,
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Text( "Cattegorry Type:- "
"$dataList[index].cattegorrytype",
style: TextStyle(color: Colors.black),
),
),
),
],
),
Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: <Widget>[
Expanded(
flex: 1,
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Theme(
data: ThemeData(
hintColor: Colors.blue,
),
child: Text( "Company Name:- "
"$dataList[index].companyname",
style: TextStyle(color: Colors.black),
),
),
),
),
Expanded(
flex: 1,
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Theme(
data: ThemeData(
hintColor: Colors.blue,
),
child: Text( "Model Name:- "
"$dataList[index].modelname",
style: TextStyle(color: Colors.black),
),
),
),
),
],
),
Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: <Widget>[
Expanded(
flex: 1,
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Theme(
data: ThemeData(
hintColor: Colors.blue,
),
child: Text( "Series Name:- "
"$dataList[index].seriesname",
style: TextStyle(color: Colors.black),
),
),
),
),
Expanded(
flex: 1,
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Theme(
data: ThemeData(
hintColor: Colors.blue,
),
child: Text( "Year Of MFG:- "
"$dataList[index].year",
style: TextStyle(color: Colors.black),
),
),
),
),
],
),
],
);
},
),
),
),
);
}
}
Please fix my issue why I am seeing a blank screen with the error "Another exception was thrown: Instance of 'DiagnosticsProperty'"
question from:
https://stackoverflow.com/questions/65883681/flutter-error-another-exception-was-thrown-instance-of-diagnosticspropertyvo 
