How to display list of map into DropdownMenuItem in Flutter - list

Question

I'm new with Flutter.
I want to display DropdownMenuItem from my list variable.
Check out my code.
// my list variable
List listUserType = [
{'name': 'Individual', 'value': 'individual'},
{'name': 'Company', 'value': 'company'}
];
// items property in DropdownMenuItem
return DropdownButtonFormField<List<Map>>(
decoration: InputDecoration(
prefixIcon: Icon(Icons.settings),
hintText: 'Organisation Type',
filled: true,
fillColor: Colors.white,
errorStyle: TextStyle(color: Colors.yellow),
),
items: listUserType.map((map) {
return DropdownMenuItem(
child: Text(map['name']),
value: map['value'],
);
}).toList());
This is the result I got
I/flutter (22528): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (22528): The following assertion was thrown building RegisterPage(dirty, state: RegisterPageState#5b83a):
I/flutter (22528): type 'List<DropdownMenuItem<dynamic>>' is not a subtype of type
I/flutter (22528): 'List<DropdownMenuItem<List<Map<dynamic, dynamic>>>>'
I do not know what is causing the error.

Answer 1

Try removing <List<Map>>
return DropdownButtonFormField(
decoration: InputDecoration(
prefixIcon: Icon(Icons.settings),
hintText: 'Organisation Type',
filled: true,
fillColor: Colors.white,
errorStyle: TextStyle(color: Colors.yellow),
),
items: listUserType.map((map) {
return DropdownMenuItem(
child: Text(map['name']),
value: map['value'],
);
}).toList());

Answer 2

Change DropdownButtonFormField<List<Map>> to DropdownButtonFormField<String> and add a String type parameter to return DropdownMenuItem<String>

Answer 3

I show the complete flow using a DropDownButtonField of YourClassView type. I create a variable called _listMenuItems which will hold your DropdownMenuItem. You must property cast its <DropdownMenuItem> or an casting error will ocurr. The _currentComboView points keeps the YourClassView object that the user has selected from the DropdownButtonField. The _loadStatusCombo is called from initState() override. It called a provder to get a list of YourClassView objects called dataViews. I map the dataViews into the _listMenuItems by casting it and using the map function. Make sure to include .tolist to flat out the results of the mapping.
YourClassView has two field: DisplayValue and DatabaseValue
YourClassView _currentComboView;
List<DropdownMenuItem> _listMenuItems =
<DropdownMenuItem<YourClassView>>[];
DropdownButtonFormField<YourClassView>(
decoration: InputDecoration(
border: OutlineInputBorder(
borderRadius: const BorderRadius.all(
const Radius.circular(2.0),
),
),
filled: true,
hintStyle: TextStyle(color: Colors.grey[800]),
hintText: "Select a Status",
fillColor: Colors.orange),
items: _listMenuItems,
isDense: true,
isExpanded: true,
value: this._currentComboView,
validator: (value) =>
value == null ? 'field required' : null,
onChanged: (YourClassView value) {
setState(() {
this._currentComboView = value;
});
}),
_loadStatusCombo() {
Provider.of<Api>(context, listen: false)
.getComboViews()
.then((dataViews) {
setState(() {
_listMenuItems =
dataViews.map<DropdownMenuItem<YourClassView>>((item) {
return DropdownMenuItem<YourClassView>(
value: item, child: Text(item.displayValue));
}).toList();
});
});
}