How to set the value of DropdownButton inside showDialog() method in Flutter? - flutter

Question

I am trying to set the value of the drop down menu inside showDialog() method, but since it's not in in build method I can't set the state of the current value. So is there a solution for this?
Here's my code
showDialog(
barrierDismissible: false,
context: context,
builder: (context) => AlertDialog(
actions: [
FlatButton(
onPressed: () {
Navigator.of(context).pop();
},
child: Text(
'Cancel'
)),
FlatButton(
onPressed: () {
Navigator.of(context).pop();
},
child: Text(
'Submit',
style: FONT_BODY_TEXT.copyWith(fontSize: 18.0),
)),
],
content: Padding(
padding: const EdgeInsets.all(8.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: [
Text(
'Select your new item',
),
DropdownButton<String>(
isExpanded: true,
value: _item,
hint: Text(
'Select an item',
),
onChanged: (newValue) {
setState(() {
_item = newValue;
});
},
items: MYLIST.map((String value) {
return DropdownMenuItem<String>(
value: value,
child: Text(
value,
style: FONT_BODY_TEXT,
),
);
}).toList(),
),
],
),
),
));
I need to get the new item from this method so I can submit the changes, that's why I am using showDialog() method so whenever I click on submit, the item is returned, and whenver I click on cancel it will not return an item. This is just for confirmation of the order.

Answer 1

Use StatefulBuilder to use setState inside Dialog and update Widgets only inside of it.
StatefulBuilder(builder: (context, setState) {
return DropdownButton<String>(
isExpanded: true,
value: item,
hint: Text(
'Select an item',
),
onChanged: (newValue) => {
setState(() {
item = newValue;
})
},
items: ['A', 'B', 'c'].map((String value) {
return DropdownMenuItem<String>(
value: value,
child: Text(value),
);
}).toList(),
);
}),