how to remove duplicate from list of objects in flutter? - flutter

Question

I'm new to flutter. I'm working on small projects which is like a scanning QR app. Here, I used hive to store scanned data in box but the problem is, it is storing duplicate values.
I need to remove that duplicate data how to do it?
code:
class PageState extends State<PassthroughQrScanPage> {
final ApiRepository repository = ApiRepository(
apiClient: ApiClient(
httpClient: http.Client(),
),
);
#override
void initState() {
super.initState();
openBox();
Prefs().reload();
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: BlocProvider(
create: (context) => PassthroughqrscanBloc(repository),
child: BlocConsumer<PassthroughqrscanBloc, PassthroughqrscanState>(
listener: (context, state) {
if (state is PassthroughqrscanEmpty) {
return scan(context);
}
if (state is PassthroughqrscanError) {
Navigator.pop(context);
ShowErrorMessage(context, state.error.message.toString());
}
if (state is PassthroughqrscanLoaded) {
List<Batch> cleared = [];
state.entity.batches.forEach((element) {
cleared.add(element);
});
// final clearedData =
// cleared.map((item) => jsonEncode(item)).toList();
// final uniqueJsonList = clearedData.toSet().toList();
// List result =
// uniqueJsonList.map((item) => jsonDecode(item)).toList();
var seen = Set<int>();
List<Batch> clearedData = cleared
.where((cleared) => seen.add(cleared.batchNumber!))
.toList();
// clearedData = [
// ...{...clearedData}
// ];
clearedData.forEach((element) {
debugPrint(
"check the values for all the sdasd ${element.batchNumber}");
box.add(Batch(
batchNumber: element.batchNumber,
isUsed: element.isUsed,
transactionId: element.transactionId));
});
print("adding ssssss ${box.values.toList()}");
// String json = jsonEncode(state.entity);
// print("------>>>>>>>>>>>D>S>D>>$json");
// Prefs().setPassthroughData(json);
Navigator.pop(context);
WidgetsBinding.instance.addPostFrameCallback((_) {
showDialog(
context: context,
builder: (ctxDialog) => PassDialog(
compoundCode: widget.compoundCode.toString(),
lotNo: widget.lotNo.toString(),
schedule_id: widget.schedule_id.toString(),
screenClosed: _screenWasClosed,
scheduleRange: widget.scheduleRange,
batchQty: widget.batchQty,
));
});
}
// return Container();
Center(
child: CircularProgressIndicator(),
);
},
builder: (context, state) {
if (state is PassthroughqrscanEmpty) {
return scan(context);
} else
return scan(context);
},
),
),
);
}
scan(BuildContext mcontext) =>
MobileScanner(
controller: MobileScannerController(facing: CameraFacing.back),
allowDuplicates: false,
onDetect: (barcode, args) {
if (barcode.rawValue == null) {
WidgetsBinding.instance.addPostFrameCallback((_) {
ScaffoldMessenger.of(context).showSnackBar(SnackBar(
content: Text("Scan correct QR"),
duration: Duration(milliseconds: 800)));
});
} else {
String code = barcode.rawValue ?? "";
debugPrint('Barcode found! $code');
if (code.isNotEmpty) {
// if (!_screenOpened) {
// _screenOpened = true;
passthroughData = jsonDecode(code);
passthroughQrScan =
PassthroughQrScanData.fromJson(passthroughData);
BlocProvider.of<PassthroughqrscanBloc>(mcontext)
..add(VerifyPassthroughBatch(
passthroughQrScan?.operationName ?? "",
widget.schedule_id.toString(),
passthroughQrScan?.transactionId ?? "",
passthroughQrScan?.transactionRange ?? ""));
buildShowDialog(context);
}
}
});
Widget ShowErrorMessage(BuildContext context, String error) {
print("------------------------------/./././$error");
WidgetsBinding.instance.addPostFrameCallback((_) {
ScaffoldMessenger.of(context).showSnackBar(SnackBar(
content: Text("Scan correct QR"),
duration: Duration(milliseconds: 800)));
});
return scan(context);
}
Future<void> openBox() async {
box = await Hive.openBox<Batch>("GetBatches");
// box = Boxes.getAllBatches();
await box.clear();
debugPrint("wwwwwwwwwwwwwwwwwkekekkkkkkkkk${box.values}");
// await box.deleteAll(box.keys);
}
}
List<Batch> batched = [];
var data;
class PassDialog extends StatefulWidget {
// const PassDialog({Key? key}) : super(key: key);
String? schedule_id;
String? compoundCode;
String? lotNo;
final Function() screenClosed;
final String? scheduleRange;
final int? batchQty;
PassDialog(
{required this.schedule_id,
required this.compoundCode,
required this.lotNo,
required this.screenClosed,
required this.scheduleRange,
required this.batchQty});
#override
State<PassDialog> createState() => _PassDialogState();
}
class _PassDialogState extends State<PassDialog> {
#override
void initState() {
batched = box.values.toSet().toList();
print("got values check for $batched");
super.initState();
}
#override
Widget build(BuildContext context) {
// List<Batch> batch = box.get("GetBatches");
//Batch batch = box?.get("GetBatches");
return SizedBox(
width: 150,
height: 100,
child: AlertDialog(
content: SingleChildScrollView(
child: Column(
children: [
// batched.forEach((element) {
for (final q in batched)
Text(
'${q.batchNumber.toString()}--${q.isUsed.toString()}--${q.transactionId.toString()}'),
// }),
Row(
children: [
ElevatedButton(
onPressed: () {
// print(values);
widget.screenClosed();
Navigator.of(
context,
rootNavigator: true,
).pop(
context,
);
},
child: Text("Continue")),
SizedBox(
width: 10,
),
ElevatedButton(
onPressed: () {
print(widget.scheduleRange);
WidgetsBinding.instance.addPostFrameCallback((_) {
Navigator.push(
context,
new MaterialPageRoute(
builder: (_) => GluePassthroughUploadPage(
id: widget.schedule_id.toString(),
compoundCode:
widget.compoundCode.toString(),
lotNo: widget.lotNo.toString(),
scheduleRange: widget.scheduleRange,
batchQty: widget.batchQty,
// getAllBatch: getBatch,
)));
});
},
child: Text("Show Add page")),
],
),
],
),
),
// Text("hohohoooooo${batched[0].batchNumber}${batched[0].isUsed}"),
),
);
}
}
Future buildShowDialog(BuildContext context) {
return showDialog(
context: context,
barrierDismissible: false,
builder: (BuildContext context) {
return Center(
child: CircularProgressIndicator(),
);
});
}
How to remove duplicate list of objects? I'm using Batch as model class. I tried many methods to solve this issue. toSet(), like that.......

Answer 1

For your Batch Model, you can filter with a function like this:
List<Batch> removeDuplicates(List<Batch> items) {
List<Batch> uniqueItems = []; // uniqueList
var uniqueIDs = items
.map((e) => e.uniqueID)
.toSet(); //list if UniqueID to remove duplicates
uniqueIDs.forEach((e) {
uniqueItems.add(items.firstWhere((i) => i.uniqueID == e));
}); // populate uniqueItems with equivalent original Batch items
return uniqueItems;//send back the unique items list
}
Replace uniqueID with the parameter you want to use for filtering duplicates

Answer 2

If you want dealing with more complex objects, store seen ids to the Set and filter away those ones that are already in the set.
final list = ['a', 'a', 'b', 'c', 'c'];
final seen = <String>{};
final uniqueList = list.where((str) => seen.add(str)).toList();
print(uniqueList); // => ['a', 'b', 'c']

Answer 3

With the help of this, You can easily get Unique data from list and it will remove duplicate value
uniqueList = uniqueList.toSet().toList();