My dropdown menu works properly after selecting a new option, but the new selection doesn't update the currently displayed option after its changed.
Widget buildCarDropdown() {
return
Center(
child: DropdownButton(
hint: Text('Please choose a car make'),
value: currentLease.carMake,
onChanged: (newValue) {
setState(() {
currentLease.carMake = newValue;
});
},
items: carMakes.map((String make) {
return DropdownMenuItem(
child: new Text(make),
value: make,
);
}).toList(),
),
);
}
carMakes is just an array of strings
currentLease contains a string for the selection of make. The value is set correctly after changing it in currentLease, and displays correctly if the widget is reloaded.
Everything seems proper here to me, not sure why it doesn't display updates properly.
Edit: What I mean by not updating it, that the drop down opens displaying all the options. Say it started at "Honda", you can then select "Acura" and though the currentLease.carMake gets updated properly, the drop down stays displaying "Honda" until it is reloaded.
Related
I am having a multiple FormBuilder dropdown in my flutter app. all of them are dependent dropdown.
i want to implement something like this:
the first of the main parent dropdown value should be auto fill and hence all other are filled or selected depending on the parents selection.
I can see the text filled in all the dropdown but as it is the dependent it is disabled for first dropdown to be clicked once.
How to fix this issue?
in the below screenshot we can see that the data is filled or been selected in every dropdown but second dropdown is still been disabled. it only gets enabled after clicking or selecting the value in first dropdown. enter image description here
Here is my code for first dropdown
padding: const EdgeInsets.all(12.0),
child: FormBuilderDropdown(
name: 'City',
decoration: InputDecoration(
labelText: 'City',
),
allowClear: true,
hint: Text(widget.callLocationModel.CityName),
initialValue: citySelected,
validator: FormBuilderValidators.compose(
[FormBuilderValidators.required(context)]),
items: cityList
.map((citySelected) => DropdownMenuItem(
value: cityChoosen,
child:new Text('$citySelected'),
))
.toList(),
onChanged: (String value){
setState(() {
citySelected= value;
//this fuction calls my second dropdown depending on first dropdown value selection
fetchSite(citySelected);
});
},
),
),
I assume all this layout is done in a stageful widget, which has a variable in it’s state for each selected value (when it’s selected). You may override initState member function and set the initial values there, so when the widget is built for the first time it will have those values preselected.
I am using the flutter pref library to create a settings page. The PrefChoice is used to show a drop down for language selection. The drop down shows the values properly. Issue is when we select anything from the drop down, the onChange method does not get called for some reason. Due to this we are not able to take action on the change in choice. Is there anything I am missing here?
PrefChoice<String>(
title: Text(AppLocalization.of(context, 'settings.language')),
pref: 'language_key',
items: const [
DropdownMenuItem(
value: LocaleConstants.LC_ENGLISH,
child: Text(LocaleConstants.ENGLISH)),
DropdownMenuItem(
value: LocaleConstants.LC_GERMAN,
child: Text(LocaleConstants.GERMAN))
],
onChange: (value) {
// This never gets called
log.d('Locale changed to - $value');
},
),
I have been trying to make an external UI that a user can use to make certain changes to a database(dynamodb) in the cloud. When I select a new value, I want it to show the change that the user wants to make, without actually changing the database. The changes are saved only when I press a button on the appbar. Also when I use setState to rebuild the button, the value doesn't change on the cloud and it also changes the value for all of the buttons in the column(works fine without a setState). The code that I have provided changes the database when I press the save icon, but the drop-down button value stays the same unless I refresh the page. I apologize if I haven't explained my issue clearly enough, this is my first time posting on Stackoverflow, and I'm still learning about how to work with flutter and aws amplify.
body: InteractiveViewer(
constrained: false,
child: DataTable(
columns: [
DataColumn(label: Text('Apt #')),
DataColumn(label: Text('Type')),
DataColumn(label: Text('Availability')),
DataColumn(label: Text('Price')),
DataColumn(label: Text('Area'))
],
rows: aprts.map<DataRow>((element) { //aprts is a list that contains apartment objects.
return DataRow(cells: [
DataCell(Text(element.aptNum.toString())),
DataCell(Text(element.type)),
DataCell(DropdownButton<String>( /// this is the part im having problems wi
value: element.availabily, // gets the value for the availability attribute for the element and stores it into value.
onChanged: (String newValue) {
availValue = newValue; //stores the newValue in a global variable that is used in a function that is used toactually make changes to the database.
tempAvail = element;
},
items: <String>['AVAILABLE', 'SOLD', 'RESERVED']
.map((String value) {
return DropdownMenuItem<String>(
value: value,
child: Text(value),
);
}).toList(),
)), // end of problem.
DataCell(TextField(
controller: TextEditingController()
..text = element.price.toString(),
onChanged: (text) {
aptPrice = text;
tempPrice = element;
},
)),
DataCell(TextField(
controller: TextEditingController()..text = element.area,
onChanged: (text) {
aptArea = text;
tempArea = element;
},
)),
]);
}).toList()),
),
What the app looks like. After pressing the button
Use
onChanged: (String newValue) {
setState(() {
availValue = newValue;
tempAvail = element;
}
)
},
because for every change in the UI you must call setState((){})
I'm back with another issue with the DropdownButton.
The DropdownButton is not enabled. I found this in api.flutter.dev
If the onChanged callback is null or the list of items is null then
the dropdown button will be disabled, i.e. its arrow will be displayed
in grey and it will not respond to input.
Here is my code now:
return new DropdownButton<String>(
hint: new Text("Select Agency"),
value: _currentAgency,
onChanged: changedDropDownAgency,
items: snapshot.data.docs.forEach((document) {
return new DropdownMenuItem<String>(
value: document.data()['name'],
child: new Text(document.data()['name']),
);
}),
);
void changedDropDownAgency(String selected_agency) {
setState(() {
_currentAgency = selected_agency;
});
globals.selectedAgency = selected_agency;
}
The forEach loop runs fine and in debug mode I can see that there is data in the document object. I don't know how to debug the DropdownButton code to see why the button is not active. Any suggestions would be helpful.
Thanks.
forEach() on Iterables does not return any value (see: https://api.dart.dev/stable/2.10.5/dart-core/Iterable/forEach.html), and thus items is null and the DropdownButton is disabled. Use map instead (https://api.dart.dev/stable/2.10.5/dart-core/Iterable/map.html). Example:
snapshot.data.docs.map<DropdownMenuItem<String>>((document) {
return new DropdownMenuItem<String>(
value: document.data()['name'],
child: new Text(document.data()['name']),
);
}).toList(),
I created a dropdownButton to allow users to select from a dropdown list which will be populated from an API. For now I am populating using a list I created.
Currently the button is displaying the items from my list but after a selection has been made the list doesnt show the selected item and still shows the hint text. What I would like to happen is after a selection has been made then the dropdownButton shows the item that was selected instead of the hint text.
in the onChanged method I added a setState in hopes of updating the _selectedValue variable to the value that was selected and displaying it in the dropdownButton.
I also added a print statement in my setState method and that does trigger and show me the value within the value variable.
Here is my code.
List<DropdownMenuItem<int>> listItems = [DropdownMenuItem(child: Text("2016"), value: 2016,), DropdownMenuItem(child: Text("2021"), value: 2021,)];
int _selectedValue;
body: DropdownButton(
value: _selectedValue,
items: listItems,
hint: Text("Select Year"),
onChanged: (int value){
setState(() {
_selectedValue = value;
print(value);
});
},
),
Your code is fine, but the problem is maybe you are initializing the _selectedValue inside the build() method. So that whenever you call set state the widget rebuilds and initialize again with the default value.
int _selectedValue;
#override
Widget build(BuildContext context) {
return DropdownButton(
value: _selectedValue,
items: listItems,
hint: Text("Select Year"),
onChanged: (int value){
setState(() {
_selectedValue = value;
print(value);
});
},
),
In case anyone else is having this issue, I had the same issue and it was driving me nuts and I was using setState() appropriately etc., It was 100% where I was defining the "initialValue" property.
I was defining it right inside the build method. That did not work, even though I had the same setup in a sister module and it indeed did work. Not sure why that is.
Once I changed the definition of that variable to the state class, it worked like a charm. Hope it saves some, some cycles.