Flutter Firebase realtime database issue - flutter

Question

here is my problem:
database I use has several categories.
Each category has several number of cases.
What I want, is to extract the information from the database, how many cases each category has and to show this information in a list. That means - to show the names of the categories AND how many children (cases) EACH category has (totalCases)...
I read data from database by using feature getNumberOfNodes and so i can get the number of children (cases) of one category by using future builder.
BUT:
If I execute code, I get now the names of all categories and the number of children (cases) which the FIRST category has.
What do I do wrong?
Here is my code, I'm struggling with:
import '../components/category_list_tile.dart';
import 'package:firebase_database/ui/firebase_animated_list.dart';
import 'package:flutter/material.dart';
import '../constants.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:firebase_database/firebase_database.dart';
import 'dart:async';
class ScreenCategoryList extends StatefulWidget {
static String id = 'screen_category_list';
final FirebaseApp app;
ScreenCategoryList({this.app});
#override
_ScreenCategoryListState createState() => _ScreenCategoryListState();
}
class _ScreenCategoryListState extends State<ScreenCategoryList> {
final referenceDatabase = FirebaseDatabase.instance;
//final _dbRef = FirebaseDatabase.instance.reference().child("de");
int counter = 0;
bool showSpinner = false;
DatabaseReference _databaseReference;
#override
void initState() {
final FirebaseDatabase database = FirebaseDatabase(app: widget.app);
_databaseReference = database.reference().child("de");
super.initState();
}
Future<int> getNumberOfNodes(int counter) async {
final response = await FirebaseDatabase.instance
.reference()
.child('de')
.child('category')
.child('$counter')
.child('cases')
.once();
var nodes = [];
response.value.forEach((v) => nodes.add(v));
print(nodes.length);
counter++;
return nodes.length;
}
#override
Widget build(BuildContext context) {
int counter = 0;
return Container(
decoration: BoxDecoration(
gradient: LinearGradient(
colors: [Colors.white, Colors.white],
),
image: const DecorationImage(
image: AssetImage("images/background.png"), fit: BoxFit.cover),
),
child: Scaffold(
backgroundColor: Colors.transparent,
appBar: AppBar(
toolbarHeight: 60.0,
elevation: 0.0,
backgroundColor: Colors.black12,
leading: Padding(
padding: EdgeInsets.only(left: 12.0, top: 12.0, bottom: 12.0),
child: Image(image: AssetImage('images/lexlogo_black.png'))),
title: Center(
child: Column(
children: [
Text(
'Kategorien',
style: TextStyle(
color: kMainDarkColor,
fontFamily: 'Roboto',
fontSize: 21.0,
fontWeight: FontWeight.bold),
),
],
),
),
actions: [
Padding(
padding: EdgeInsets.only(right: 8.0),
child: IconButton(
icon: Icon(Icons.more_vert_rounded),
iconSize: 30.0,
color: kMainDarkColor,
onPressed: () {},
//onPressed: onPressMenuButton,
),
),
],
),
body: FutureBuilder<int>(
future: getNumberOfNodes(counter),
builder: (BuildContext context, AsyncSnapshot<int> casesSnapshot) {
if (casesSnapshot.hasData) {
return FirebaseAnimatedList(
reverse: false,
padding: EdgeInsets.symmetric(horizontal: 10.0, vertical: 20.0),
query: _databaseReference.child('category'),
itemBuilder: (
BuildContext context,
DataSnapshot categorySnapshot,
Animation<double> animation,
int index,
) {
int numberOfCases = casesSnapshot.data;
print('$counter, $numberOfCases');
return CategoryListTile(
title: categorySnapshot.value['name'].toString(),
successfulCases: 10,
totalCases: casesSnapshot.data,
onTitleClick: () {},
onInfoButtonClick: () {},
);
},
);
} else if (casesSnapshot.hasError) {
return Center(
child: Column(
children: [
Icon(
Icons.error_outline,
color: Colors.red,
size: 60,
),
Padding(
padding: const EdgeInsets.only(top: 16),
child: Text('Error: ${casesSnapshot.error}'),
)
],
),
);
} else {
return Center(
child: Column(
children: [
SizedBox(
child: CircularProgressIndicator(),
width: 60,
height: 60,
),
Padding(
padding: EdgeInsets.only(top: 16),
child: Text('Awaiting result...'),
)
],
),
);
}
},
),
),
);
}
}

Answer 1

got it...
here is the code, that worked for me:
class _ScreenCategoryListState extends State<ScreenCategoryList> {
final referenceDatabase = FirebaseDatabase.instance;
bool showSpinner = false;
DatabaseReference _databaseReference;
#override
void initState() {
final FirebaseDatabase database = FirebaseDatabase(app: widget.app);
_databaseReference = database.reference().child("de");
super.initState();
}
Future<Map<int, int>> getNumberOfNodes() async {
Map<int, int> caseNumbers = new Map<int, int>();
// read number of category nodes
final categoriesNumbersResponse = await FirebaseDatabase.instance
.reference()
.child('de')
.child('category')
// .child('0')
// .child('cases')
.once();
var categoryNodes = [];
categoriesNumbersResponse.value.forEach((v) => categoryNodes.add(v));
int numberOfCategories = categoryNodes.length;
//read number of cases in category
for (int i = 0; i < numberOfCategories; i++) {
final caseResponse = await FirebaseDatabase.instance
.reference()
.child('de')
.child('category')
.child('$i')
.child('cases')
.once();
var caseNodes = [];
caseResponse.value.forEach((v) => caseNodes.add(v));
int numberOfCases = caseNodes.length;
caseNumbers[i] = numberOfCases;
}
return caseNumbers;
}
#override
Widget build(BuildContext context) {
return Container(
decoration: BoxDecoration(
gradient: LinearGradient(
colors: [Colors.white, Colors.white],
),
image: const DecorationImage(
image: AssetImage("images/background.png"), fit: BoxFit.cover),
),
child: Scaffold(
backgroundColor: Colors.transparent,
appBar: AppBar(
toolbarHeight: 60.0,
elevation: 0.0,
backgroundColor: Colors.black12,
leading: Padding(
padding: EdgeInsets.only(left: 12.0, top: 12.0, bottom: 12.0),
child: Image(image: AssetImage('images/lexlogo_black.png'))),
title: Center(
child: Column(
children: [
Text(
'Kategorien',
style: TextStyle(
color: kMainDarkColor,
fontFamily: 'Roboto',
fontSize: 21.0,
fontWeight: FontWeight.bold),
),
],
),
),
actions: [
Padding(
padding: EdgeInsets.only(right: 8.0),
child: IconButton(
icon: Icon(Icons.more_vert_rounded),
iconSize: 30.0,
color: kMainDarkColor,
onPressed: () {},
//onPressed: onPressMenuButton,
),
),
],
),
body: FutureBuilder<Map<int, int>>(
future: getNumberOfNodes(),
builder: (BuildContext context,
AsyncSnapshot<Map<int, int>> casesSnapshot) {
if (casesSnapshot.hasData) {
return FirebaseAnimatedList(
reverse: false,
padding: EdgeInsets.symmetric(horizontal: 10.0, vertical: 20.0),
query: _databaseReference.child('category'),
itemBuilder: (
BuildContext context,
DataSnapshot categorySnapshot,
Animation<double> animation,
int index,
) {
int numberOfCases = casesSnapshot.data[index];
//print('number of cases $_counter, $numberOfCases');
return CategoryListTile(
title: categorySnapshot.value['name'].toString(),
successfulCases: 10,
totalCases: numberOfCases,
onTitleClick: () {},
onInfoButtonClick: () {},
);
},
);
} else if (casesSnapshot.hasError) {
return Center(
child: Column(
children: <Widget>[
Icon(
Icons.error_outline,
color: Colors.red,
size: 60,
),
Padding(
padding: const EdgeInsets.only(top: 16),
child: Text('Error: ${casesSnapshot.error}'),
)
],
),
);
} else {
return Center(
child: Column(
children: <Widget>[
SizedBox(
child: CircularProgressIndicator(),
width: 60,
height: 60,
),
Padding(
padding: EdgeInsets.only(top: 16),
child: Text('Awaiting result...'),
)
],
),
);
}
},
),
),
);
}
}