Issue
I have a List with functions in a Provider in my Main File. If I update this List trough the functions in my widget (by pressing the buttons), it seems to work but doesn´t change anything on the screen…
I have two Screens, which should be filed with the same List, so I need the Provider Functions.
In my opinion (which of course don´t have to be right) I code the functions right, so the problem may be that the screens didn´t update, altaugh I used the Consumer. It would be great if you can show me the mistake in my Code.
I would be very happy if you could look at my problem – Thank you!
MainFile:
void main() => runApp(
MultiProvider(
providers: [
ChangeNotifierProvider(create: (_) => MyList()),
],
child: MyApp(),
),);
class MyList extends ChangeNotifier {
final List<String> heute = [
'Ereignis 1',
'Ereignis 2',
'Ereignis 3',
'Ereignis 4',
'Ereignis 5'
];
UnmodifiableListView<String> get items => UnmodifiableListView(heute);
int get totallength => heute.length;
void addItem(String item) {
heute.add(item);
notifyListeners();
}
void deleteItem(int index) {
heute.removeAt(index);
notifyListeners();
}
void removeAll() {
heute.clear();
notifyListeners();
}
}Widget:
class ContainerListe extends StatefulWidget {
@override
_ContainerListeState createState() => _ContainerListeState();
}
class _ContainerListeState extends State<ContainerListe> {
final heute = MyList();
void addItem(String item) {
setState(() {
heute.addItem(item);});
Navigator.of(context).pop();
}
void removeAll(){setState(() {
setState(() {
heute.removeAll();});
});}
void deleteItem(int index) {
setState(() {
heute.deleteItem(index);
});}
void newEntry() {
showDialog<AlertDialog>(
context: context,
builder: (BuildContext context)
{return AddItemDialogWHW(addItem);});}
@override
Widget build(BuildContext context) {
final heute = MyList();
final elemente = heute.items;
return Consumer<MyList>(
builder: (context, mylist, child)
{
return
Column(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
Container(
width: 400.0,
height: 550.0,
child: Align(
alignment: Alignment.bottomCenter,
child:
ListView.builder(
itemCount: Provider
.of<MyList>(context, listen: true)
.totallength,
itemBuilder: (context, i) {
return
Column(
children: [
ContainerVorlage(
elemente[i],
() => deleteItem(i),
),
SizedBox(
height: 15,
),
],
)
;
},
)
)),
SizedBox(
height: 40,
),
AddButton(
() => newEntry(),
),
]);
});
}
}
//More CodeSolution
First, remove this line from _ContainerListeState
final heute = MyList();
Then use the methods from the MyList object, as you can use
return Consumer<MyList>(builder: (context, mylist, child)
... // rest code
ContainerVorlage(
elemente[i],
() => mylist.deleteItem(i),
),
Answered By – meditat
Answer Checked By – Robin (FlutterFixes Admin)