'Getting ExpansionPanelList to work inside Streambuilder in flutter
I'm trying to arrange some data streamed from Firebase with an ExpansionPanellist. The panelList is placed inside a StreamBuilder, and above the StreamBuilder i have a SingleChildScrollView.
I am able to get the list showing with the headers, but i can't get the expand/collapse function to work, so I am not able to see the body-text. screenshot of the list
The expanding/collapinsg function worked outside the Streambuilder, but I was not able to access the data from Firebase then.
Any help will be much appreciated! If this is the wrong way of doing this, I will also be grateful for any pointers to alternative ways of achieving this. (There won't be any data added to the server while looking at past climbs and graphs, so a streambuilder might not be necessary if there are easier/better ways).
-Kristian
class Graphs extends StatefulWidget {
static String id = 'graphs_screen';
@override
_GraphsState createState() => _GraphsState();
}
@override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
body: DefaultTabController(
length: 3,
child: Scaffold(
appBar: AppBar(
bottom: TabBar(tabs: [
Tab(text: 'Graphs'),
Tab(text: 'Stats'),
Tab(text: 'Climbs'),
]),
),
body: TabBarView(
children: [
//Image.asset('assets/images/line_graph.png'),
Expanded(child: NumericComboLinePointChart.withSampleData()),
Container(
child: Text(''),
),
SingleChildScrollView(
child: DataStream(),
),
],
)),
),
);
}
}
class DataStream extends StatefulWidget {
@override
_DataStreamState createState() => _DataStreamState();
}
class _DataStreamState extends State<DataStream> {
@override
Widget build(BuildContext context) {
return StreamBuilder<QuerySnapshot>(
stream: _firestore
.collection('climbs')
.orderBy('Date', descending: true)
.snapshots(),
builder: (context, snapshot) {
List<ExpansionItem> expansionList = <ExpansionItem>[];
if (snapshot.hasData) {
final alldata = snapshot.data.docs;
for (var data in alldata) {
final dataFunction = data.data();
final grades = dataFunction['gradeScore'];
final climbDate = dataFunction['Date'];
final climbDateT = DateTime.fromMicrosecondsSinceEpoch(
climbDate.microsecondsSinceEpoch);
String climbDateString =
"${climbDateT.year.toString()}-${climbDateT.month.toString().padLeft(2, '0')}-${climbDateT.day.toString().padLeft(2, '0')} ${climbDateT.hour.toString()}-${climbDateT.minute.toString()}";
final climber = dataFunction['sender'];
final currentUSer = loggedInUser.email;
if (climber == loggedInUser.email) {
expansionList.add(ExpansionItem(
dateTimeHeader: climbDateString,
climbs: grades.toString()));
}
}
}
return ExpansionPanelList(
expansionCallback: (int index, bool isExpanded) {
setState(() {
print('tap registered');
expansionList[index].isExpanded = !isExpanded;
});
},
children: expansionList.map((ExpansionItem item) {
return ExpansionPanel(
headerBuilder: (BuildContext context, bool isExpanded) {
return Container(
child: Text(item.dateTimeHeader),
);
},
body: Container(
child: Text(item.climbs),
),
isExpanded: item.isExpanded,
);
}).toList(),
);
});
}
}
class ExpansionItem {
ExpansionItem({this.isExpanded: false, this.dateTimeHeader, this.climbs});
bool isExpanded;
final String dateTimeHeader;
final String climbs;
}
Solution 1:[1]
I also ran into this issue and managed to develop a "work-around" (sorry in advance, it's a bit messy).
The reason your expansion tiles are not expanding is due to the nature of expansionCallback function. Once you press the expand button it also causes your StreamBuilder to rebuild. Therefore, since you're initializing "expansionList" within the StreamBuilder it will reset "isExpanded" back to false no matter how many times you press it. So your best option is to initialize the expansionList outside of the StreamBuilder and modify it from within. Check below for my solution but I welcome anyone to optimize it and/or share a better one.
class ExpansionItem {
String headerValue;
bool isExpanded;
SplitObject item;
ExpansionItem({this.item, this.headerValue, this.isExpanded = false});
}
class MyExample extends StatefulWidget{
@override
_MyExampleState createState() => _MyExampleState();
}
class _MyExampleState extends State<MyExample> {
//Pick a number as large as you see fit to always be more than necessary.
List<ExpansionItem> expansionItems = List<ExpansionItem>.generate('anyNumber', (int index)=> ExpansionItem(isExpanded: false,));
@override
Widget build(BuildContext context) {
return GestureDetector(
child: Scaffold(
appBar: AppBar(
title: Text('Split',style: Theme.of(context).textTheme.headline3,),
),
body: SingleChildScrollView(
padding: const EdgeInsets.all(8),
child: Container(
child: StreamBuilder(
builder: (context, streamData){
if(streamData.hasData){
List<SplitObject> items = streamData.data;
//Save data to Expansion list by iterating through it.
for (var i = 0; i < items.length; i++){
try {
expansionItems[i].item =items[i];
expansionItems[i].headerValue =items[i].itemName;
} catch (e) {
// Catch any range errors after trimming list.
if(e.toString().contains('RangeError')) {
expansionItems.add(ExpansionItem(
item: items[i], headerValue: items[i].itemName));
}
}
}
// Trim list
expansionItems = expansionItems.getRange(0, items.length).toList();
return _buildListPanel(expansionItems);
} else {
return ListTile(
title: Text('No items to split.'),
);
}
},
stream: DatabaseService().splitItemData,
),
),
),
)
);
}
Widget _buildListPanel(List<ExpansionItem> expansionItems){
// print(expansionItems[0].isExpanded);
return ExpansionPanelList(
expansionCallback: (int index, bool isExpanded){
setState(() {
expansionItems[index].isExpanded = !isExpanded;
// print(expansionItems[index].isExpanded);
});
},
children: expansionItems.map<ExpansionPanel>((ExpansionItem item){
return ExpansionPanel(
headerBuilder: (BuildContext context, bool isExpanded){
print(item.isExpanded);
return Padding(
padding: const EdgeInsets.all(8.0),
child: Column(),
);
},
body: Container(),
isExpanded: item.isExpanded,
);
}).toList(),
);
}
}
Solution 2:[2]
You should create a class where your Expansion List will be, then your Stream builder must call it. Doing it this way Expansion Panel List callback will function just normal.
Look:
class _ExpansionPanelClass extends State<ExpansionPanelClass> {
@override
Widget build(BuildContext context) {
return ExpansionPanelList(
elevation: 3,
expansionCallback: (index, isExpanded) {
setState(() {
widget.product[index]['isExpanded'] = !isExpanded;
});
},
animationDuration: const Duration(milliseconds: 600),
children: widget.product
.map(
(item) => ExpansionPanel(
canTapOnHeader: true,
backgroundColor:
item['isExpanded'] == true ? Colors.cyan[100] : Colors.white,
headerBuilder: (_, isExpanded) => Container(
padding:
const EdgeInsets.symmetric(vertical: 15, horizontal: 30),
child: Text(
item['title'],
style: const TextStyle(fontSize: 20),
)),
body: Container(
padding:
const EdgeInsets.symmetric(vertical: 15, horizontal: 30),
child: Text(item['description']),
),
isExpanded: item['isExpanded'],
),
)
.toList(),
);
}
}
Then from your StreamBuilder:
StreamBuilder<QuerySnapshot>(
stream: dbProducts
.collection(ids[i])
.orderBy('order', descending: false)
.snapshots(),
builder: (context, snapshot) {
if (snapshot.hasData) {
List<Map<String, dynamic>> _items = [];
for (var document in snapshot.data!.docs) {
Map data = Map.from(document.data() as Map);
if (data['hide'] == false) {
Map<String, dynamic> map = {
'id': _items.length,
'title': data['name'],
'description': data['ingredients'],
'isExpanded': false
};
_items.add(map);
}
}
return ExpansionPanelClass(product: _items);
} else {
return const Center(
child: CircularProgressIndicator(
color: Colors.brown,
),
);
}
},
),
That's all.
Solution 3:[3]
getNamePopularityDataByYear is an instance method as per the given definition of the class CosAPI. To use it, we should be invoking it over an instance of CosAPI, like...
const nameData: string = await new CsoAPI().getNamePopularityDataByYear(year);
If we want to use it the way as mentioned above, then we will have to qualify the function getNamePopularityDataByYear with static keyword, like...
...
static async getNamePopularityDataByYear(year:number): Promise<number> {
...
}
Choose what way to use that function and adjust accordingly.
Sources
This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.
Source: Stack Overflow
| Solution | Source |
|---|---|
| Solution 1 | Randy Nolden |
| Solution 2 | DharmanBot |
| Solution 3 | Nalin Ranjan |