DropdownButtonFormField reset value to initial - flutter

How do I reset or select the first value from DropdownButtonFormField?
The answer from here How to reset value in Flutter DropdownButtonFormField is outdated and not suitable for the newer flutter version.
DropdownButtonFormField:
final etSkillScore1Key = GlobalKey<FormState>();
...
DropdownButtonFormField(
key: etSkillScore1Key,
decoration: const InputDecoration(labelText: 'Select value'),
onChanged: (val) async {
setState(() {
etSkillScore1 = val as int;
});
FocusScope.of(context).requestFocus(FocusNode());
},
value: etSkillScore1,
items: priorities2.map((db.Priority priorities) {
return DropdownMenuItem(
child: Text(priorities.name),
value: priorities.value,
);
}).toList(),
),
Button for resetting the value:
IconButton(
onPressed: () {
//ERORR: Null check operator used on a null value
etSkillScore1Key.currentState!.reset();
},
icon: Icon(
Icons.close,
))
Error:
======== Exception caught by gesture
The following _CastError was thrown while handling a gesture:
Null check operator used on a null value
If I use
etSkillScore1Key.currentState?.reset();
then nothing happens

First of all you are not using the correct key it should be a GlobalKey<FormFieldState>(), but even then the reset() would not work.
The reason for this is because of the implementation of DropdownButtonFormField:
DropdownButtonFormField({
// ...
T? value,
// ...
}) : super(
// ...
initialValue: value,
// ...
);
(source: Flutter Documentation)
As you can see the value property of DropdownButtonFormField is what defines the initialValue of the FormField so when you are rebuilding your form field and changing the value of etSkillScore1 it is also changing the value of your DropdownButtonFormField.initialValue.
Solution 1
If you want your reset() to work then you can remove the property value of DropdownButtonFormField so the initialValue won't change with etSkillScore1.
DropdownButtonFormField<int>(
key: etSkillScore1Key,
decoration: const InputDecoration(labelText: 'Select value'),
onChanged: (val) {
etSkillScore1 = val;
FocusScope.of(context).requestFocus(FocusNode());
},
// value: etSkillScore1,
items: priorities2.map((db.Priority priorities) {
return DropdownMenuItem<int>(
child: Text(priorities.name),
value: priorities.value,
);
}).toList(),
)
Try the full example on DartPad
Solution 2
Do not set the value property with etSkillScore1, if you want to initialize your widget with an initial value then do it like this:
DropdownButtonFormField<int>(
key: etSkillScore1Key,
decoration: const InputDecoration(labelText: 'Select value'),
onChanged: (val) {
etSkillScore1 = val;
FocusScope.of(context).requestFocus(FocusNode());
},
value: 1, // Use a fixed value that won't change
items: priorities2.map((db.Priority priorities) {
return DropdownMenuItem<int>(
child: Text(priorities.name),
value: priorities.value,
);
}).toList(),
)
As your value will be fixed then when DropdownButtonFormField is rebuild it will keep 1 as its initial value.

Related

Flutter: disable DropdownButtonFormField option

I have this widget:
DropdownButtonFormField<String>(
hint: Text(translate('payments.select_frequency')),
value: frequency,
items: frequencies.map((String value) {
return DropdownMenuItem<String>(
value: value,
child: Text(
translate("expense.$value"),
style: TextStyle(
color: disabledFrequencies.contains(value) ? Colors.grey : null,
),
),
);
}).toList(),
onChanged: (value) async {
if (!disabledFrequencies.contains(value)) {
setState(() {
frequency = value;
});
}
},
validator: (value) {
if (value == null) {
return translate('fill_field');
}
return null;
},
);
This generates something like this:
Here I should be able to just click the first option but I can select any of them. I opened this issue a while ago in Flutter repo and they mentioned it's not an issue.
What's the option then?
There is enable property on DropdownMenuItem control the tap accessibility.
return DropdownMenuItem<String>(
value: value,
enabled: !disabledFrequencies.contains(value), //this
onTap: () {
Whether or not a user can select this menu item.
Defaults to true.

Flutter Dropdownbutton selected value is not changing

Flutter Dropdownbutton selected value is not changing I am using dropdownbutton and mapping data using Product model but onchange my value is not changing
DropdownButtonHideUnderline(
child: DropdownButton<Product>(
hint: Text("Select Product"),
dropdownColor: Colors.white,
isExpanded: true,
items: _productController.products
.map((Product value) {
return new DropdownMenuItem<Product>(
value: value,
child: new Text(value.productName),
);
}).toList(),
onChanged: (Product val) {
_stockController.price.text = val.price;
_stockController.productName.text = val.productName;
selectedProduct = val.productName;
TextStyle(color: Colors.black);
setState(() {});
},
),
),
You didn't specify the value property of this widget. I think it should be set to value of selectedProduct.
And what the separate TextStyle? It is used as value for style property of widgets and cannot be used as standalone.

Retrieve the value of a Slider and send it to MySQL

I'm working on a online survey app in flutter and the API in PHP with MySQL for the database.
I'm using TextFormField for the Name field and wanted to use Slider for Age field.
I can retrieve the value from TextFormField using onSaved: (e) => name = e,, But I don't know how to retrieve the value of the Slider.
I tried to change the value to string using age.toString() but It says:
The argument type 'String' can't be assigned to the parameter type.
Here is my Form() code:
Form(
key: _key,
child: ListView(
children: [
TextFormField(
onSaved: (e) => name = e,
decoration: InputDecoration(labelText: "Name"),
),
Slider(
min: 10,
max: 100,
value: age,
onChanged: (value) {
setState(() {
age = value;
});
},
label: "$age",
),
MaterialButton(
onPressed: () {
check();
},
child: Text("submit"),
)
]
)
),

Flutter: There should be exactly one item with [DropdownButton]'s value

I am trying to create a dropdown button in Flutter. I am getting a List from my database then I pass the list to my dropdownButton everything works the data is shown as intended but when I choose an element from it I get this error:
There should be exactly one item with [DropdownButton]'s value: Instance of 'Tag'.
Either zero or 2 or more [DropdownMenuItem]s were detected with the same value
'package:flutter/src/material/dropdown.dart':
Failed assertion: line 805 pos 15: 'items == null || items.isEmpty || value == null ||
items.where((DropdownMenuItem<T> item) {
return item.value == value;
}).length == 1'
I tried setting DropdownButton value to null it works but then I can't see the chosen element.
Here is my code:
FutureBuilder<List<Tag>>(
future: _tagDatabaseHelper.getTagList(),
builder: (BuildContext context, AsyncSnapshot<List<Tag>> snapshot) {
if (!snapshot.hasData) {
return Center(
child: CircularProgressIndicator(),
);
}
return ListView(
children: <Widget>[
SizedBox(
height: MediaQuery.of(context).size.height * 0.2,
),
Container(
margin: EdgeInsets.symmetric(
horizontal: MediaQuery.of(context).size.width * 0.07),
child: Theme(
data: ThemeData(canvasColor: Color(0xFF525A71)),
child: DropdownButton<Tag>(
value: _selectedTag,
isExpanded: true,
icon: Icon(
Icons.arrow_drop_down,
size: 24,
),
hint: Text(
"Select tags",
style: TextStyle(color: Color(0xFF9F9F9F)),
),
onChanged: (value) {
setState(() {
_selectedTag = value;
});
},
items: snapshot.data.map((Tag tag) {
return DropdownMenuItem<Tag>(
value: tag,
child: Text(
tag.tagTitle,
style: TextStyle(color: Colors.white),
),
);
}).toList(),
value: _selectedTag,
),
),
),
I used futureBuilder to get my List from database.
Well, since no problem has an exact same solution. I was facing the same issue with my code. Here is How I fixed this.
CODE of my DropdownButton:
DropdownButton(
items: _salutations
.map((String item) =>
DropdownMenuItem<String>(child: Text(item), value: item))
.toList(),
onChanged: (String value) {
setState(() {
print("previous ${this._salutation}");
print("selected $value");
this._salutation = value;
});
},
value: _salutation,
),
The Error
In the code snippet below, I am setting the state for a selection value, which is of type String. Now problem with my code was the default initialization of this selection value.
Initially, I was initializing the variable _salutation as:
String _salutation = ""; //Notice the empty String.
This was a mistake!
Initial selection should not be null or empty as the error message correctly mentioned.
'items == null || items.isEmpty || value == null ||
And hence the crash:
Solution Initialize the value object with some default value. Please note that the value should be the one of the values contained by your collection. If it is not, then expect a crash.
String _salutation = "Mr."; //This is the selection value. It is also present in my array.
final _salutations = ["Mr.", "Mrs.", "Master", "Mistress"];//This is the array for dropdown
Might also get this error if trying to set value of dropdown with a class instance;
var tag1 = Tag();
var tag2 = Tag();
print(tag1 == tag2); // prints false, dropwdown computes that value is not present among dropdown options
To solve this override operator ==:
class Tag{
String name = "tag";
#override
bool operator ==(Object other) => other is Tag && other.name == name;
#override
int get hashCode => name.hashCode;
}
or use https://pub.dev/packages/equatable lib
class Tag extends Equatable{
String name = "tag";
#override
List<Object> get props => [name];
}
I had the same problem. The solution is simple: you have to be sure that the String that is your default dropdownvalue is contained in the list that you want to use in your dropdownmenu. If you wanted to, let’s say, use a list from an api, you should be sure to know at least one value of that list, so that you could assign it to the variable that is your default dropdownvalue.
Here I want display a list that I obtain from an api. In order to not obtain the error, I set my defaultdropdownvalue with the name ‘Encajes’ that is one of the existing categories that my list contains.
String dropdownValue = "Encajes";
items: categoriesString
.map<DropdownMenuItem<String>>((String value) {
return DropdownMenuItem<String>(
value: value,
child: Text(value),
);
}).toList(),
Code of my dropdown
child: DropdownButton(
items: _currencies.map((String value) {
return DropdownMenuItem<String>(
child: Text(value),
value: value,
);
}).toList(),
value: 'Rupees',
onChanged: (String newValueSelected) {
// Your code to execute, when a menu item is selected from
dropdown
},
))
var _currencies = ['Rupee','Dollar','Pound'];
I faced same error because the value in the dropdown code block is not matching with any of the fields in _currencies
Okay, some of the answers on this thread will definitely help you resolve the issue. But it is important to clarify why this issue occurs in the first place and what the DropdownButton expects from you.
To give you a little background on the issue it is important to understand how two instances of dart objects are compared.
You will very likely not see the above error if your DropdownButton is dealing with a List of int, String, bool, etc.
This is because you can directly compare primitive types and you would get the expected result.
for instance
int x = 5;
int z = 10;
int y = 5;
String foo= 'hello';
String bar = 'hello;
x == z; // false
x == y; // true
foo == bar; // true
But when dealing with Custom Objects you have to be extra careful and you must ensure you override the "==" operator so that dart knows how to compare instances of your custom object. By default, two objects are equal if they are of the same instance.
consider the Tag class,
class Tag{
final String name;
final String code;
Tag({this.name,this.code});
}
final tag1 = Tag(name:'foo', code: 'hello');
final tag2 = Tag(name:'foo', code: 'hello');
Tag tag3 = tag1;
when you compare
tag3==tag1 dart would return true as expected, But when you compare tag1 == tag2, the dart would return false, since both objects are not of the same instance.
So to deal with this issue you need to override the == operator as shown below
class Tag{
final String name;
final String code;
Tag({this.name,this.code});
#override
bool operator ==(Object other){
return identical(this, other) ||
(other.runtimeType == runtimeType &&
other is Tag &&
other.name == name &&
other.code == code
}
}
Now when you compare tag1 ==tag2 it would return true.
This is documented in the official docs here https://dart.dev/guides/language/effective-dart/design#equality
Coming to the DropdownButton error it expects
items is not null
items is not empty
value is not null
value must be present only once in items
Point 4 would fail if you are using Custom objects without overriding the == operator and hence you would get the above error.
TLDR;
So to deal with the error, ensure the above 4 points satisfy and override the == operator so that dart can compare instances of your Tag class as you would expect.
just make the tag class extend from Equatable and pass the attributes to the props.. this did the trick for me.
class Tag extends Equatable{
String id;
String name;
Tag(this.id, this.name);
#override
List<Object> get props => [id,name];
}
I have had the same issue and surprisingly, there were duplicates in my list of items which were being fetched from a remote DB.
Each time I fetched the data from the server (when a new app user logged in), the data had no duplicates but the same data was being added to the list multiple times because I was logging in multiple users on the same device. Maybe your bug is something similar.
So, make sure you remove any duplicates in the snapshot.data before setting them as items of the DropDownButton.
i had the same Error and my default value was not present in the listItems was mapping in the Dropdown Button as :
String defaultvalue = 'selectCategorie'
const List<String> Subcategories = ['category 1','category 2','category 3'...];
Had to Change to this :-
String defaultvalue = 'selectCategorie';
const List<String> Subcategories = ['selectCategorie','category 1','category 2','category 3'...];
now when you pass the defaultvalue in the DropdownButton no errors
DropdownButton (
item:[]
onChanged: (String values){
print(values);
setState(() {
defaultValue = values;
});
},
value: defaultValue,
)
I used a trick. The selected item make as first index item in the list .So when changing item at every time remove the item from list and reinsert the item as first item in the list . Please refer the below code. Here iam using Object as the drop down item and the widget i make it as extracted function. and also before calling the dropDownButton function make
//items list like below
List<LeaveType> items = [
(id=1,name="Sick"),
(id=2,name="Paid")
]
selectedLeave = null;
Row leaveTypeDropDown(StateSetter setCustomState, List<LeaveType> items) {
if(selectedLeave != null){
items.remove(selectedLeave);
items.insert(0, selectedLeave);
}
return Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children : [
text("Select Leave Type",textSize: 15),
Padding(padding: const EdgeInsets.all(5)),
Expanded(
child: Container(
padding: const EdgeInsets.only(left: 10.0, right: 10.0),
decoration: BoxDecoration(
border: Border.all(color: Colors.black,width: 1),
borderRadius: const BorderRadius.all(Radius.circular(10.0)),
),
child: DropdownButtonHideUnderline(
child: DropdownButton<LeaveType>(
isExpanded: true,
//initial value
value: selectedLeave != null ? items[0] : null,
icon: const Icon(Icons.arrow_downward),
iconSize: 24,
elevation: 16,
hint: text("Leave Type"),
style: const TextStyle(
color: Colors.black
),
onChanged: (LeaveType value) {
setCustomState(() {
selectedLeave = value;
items.remove(selectedLeave);
items.insert(0, selectedLeave);
});
},
items: items
.map((leave) {
return new DropdownMenuItem<LeaveType>(
value: leave,
child: text(leave.name),
);
}).toList(),
),
),
),
),
]
);
}
I changed as below and it got solved:
Initial Code:
List<GamesModel> users = <GamesModel>[
new GamesModel(1,"Option1"),
new GamesModel(2,"Option2"),
];
return users;
Changed Code:
List<GamesModel> users = <GamesModel>[
const GamesModel(1,"Option1"),
const GamesModel(2,"Option2"),
];
return users;
If anybody want i can put the whole code
Note that if the list has duplicated values, it will also has this error.
For example, if languages = ["English", "English", "French"];
then if I set the default language = "English".
DropdownButton<String>(
value: language,
icon: const Icon(Icons.arrow_downward),
iconSize: 24,
elevation: 16,
style: const TextStyle(color: AppColors.highLightTextColor),
underline: Container(
height: 1,
color: AppColors.underLineColor,
),
onChanged: (String? newValue) async {
setState(() {
language = newValue;
});
},
items: languages.map<DropdownMenuItem<String>>((String value) {
return DropdownMenuItem<String>(
value: value,
child: Text(value),
);
}).toList(),
),
Remove the duplicate values, then it works.
So I found a solution.
I created empty List to hold my Tag objects.
List<Tag> _tagList = [];
Then, in my initState i assigned the list i get from database to the previous List
#override
void initState() {
super.initState();
_tagDatabaseHelper.getTagList().then((foo) {
setState(() {
_tagList = foo;
});
});
}
Finally My DropdownButton code :
DropdownButton<Tag>(
isExpanded: true,
icon: Icon(
Icons.arrow_drop_down,
size: 24,
),
hint: Text(
"Select tags",
style: TextStyle(color: Color(0xFF9F9F9F)),
),
items: _tagList.map((foo) {
return DropdownMenuItem(
value: foo,
child: Text(foo.tagTitle),
);
}).toList(),
onChanged: (value) {
setState(() {
_selectedTag = value;
});
},
value: _selectedTag,
),
In my case, i use empty String for default
value : dropdownValue != "" ? dropdownValue : null
Like this, errors be gone
The exact answer is:
keep "value" null before user selection:
String selectedValue = '';
And in the DropdownButton2 Widget:
...
value: selectedValue.isEmpty ? null : selectedValue,
...
It says if selectedValue is empty then give null but when user select a value then give selectedValue
you can avoid the null value using a ternary operator:
Container(
child:
new DropdownButton<String>(
value: dropdownValue ?? "1",
icon: const Icon(Icons.arrow_downward),
iconSize: 24,
elevation: 16,
style: const TextStyle(color: Colors.black, fontSize: 18),
underline: Container(height: 2, color: Colors.white24, ),
items: <String>['1', '2', '3', '5'].map((String value) {
return new DropdownMenuItem<String>(
value: value,
child: new Text(value),
);}).toList(),
onChanged: (value) {
setState(() { dropdownValue=value;});
},
)),
This error also occurs if you forget to give dropdown menu items a value.
==== WORKS ====
<String>['A', 'B', 'C'].map<DropdownMenuItem<String>>((vehicle) {
print("vehicle is $vehicle");
print("vehicle is equal ${vehicle == x.value}");
return DropdownMenuItem<String>(
value: vehicle,
child: Text(
// vehicle.vehicleInfo!.vehicleType!,
vehicle,
style: TextStyle(
color: Colors.grey[600],
),
),
);
}).toList(),
==== DOESNT WORK ====
<String>['A', 'B', 'C'].map<DropdownMenuItem<String>>((vehicle) {
return DropdownMenuItem<String>(
child: Text(
vehicle,
style: TextStyle(
color: Colors.grey[600],
),
),
);
}).toList(),
DropdownButton<String>(
iconEnabledColor: Colors.cyan.withOpacity(.6),
isExpanded: true,
itemHeight: 50,
iconSize: 30,
hint: Text("Choose Province"),
items: _provinces
.map((e) => DropdownMenuItem(
child: Text(e),
value: e,
))
.toList(),
value: _Province,
onChanged: (String? value) async{
final respnose=await FirebaseFirestore.instance.collection('city').where('provinceName',isEqualTo: value).get();
_city=[];
for(var item in respnose.docs){
print(item.data());
_city.add(item.data()['name']);
}
print(_Province);
setState(() {
_city=_city;
_Province = value;
});
},
),
SizedBox(height: 20,),
DropdownButton<String>(
iconEnabledColor: Colors.cyan.withOpacity(.6),
isExpanded: true,
itemHeight: 50,
iconSize: 30,
hint: Text("Choose City"),
items:_city
.map((e) => DropdownMenuItem(
child: Text(e),
value: e,
))
.toList(),
value: _City,
onChanged: (String? value) async{
setState(() {
_town=[];
_Town=null;
});
print(_town);
final respnose=await FirebaseFirestore.instance.collection('town').where('cityName',isEqualTo: value).get();
print(respnose.docs);
for(var item in respnose.docs){
print(item.data());
_town.add(item.data()['name']);
}
print(_town);
print(_City);
setState(() {
_City = value;
_town=_town;
});
},
),
SizedBox(height: 20,),
if(true)
DropdownButton<String>(
iconEnabledColor: Colors.cyan.withOpacity(.6),
isExpanded: true,
itemHeight: 50,
iconSize: 30,
hint: Text("Choose Town"),
items:_town
.map((e) => DropdownMenuItem(
child: Text(e),
value: e,
)
)
.toList(),
value: _Town,
onChanged: (String? value)async {
print(_Town);
setState(() {
_Town = value;
});
I had the same problem, and the solution is to fill the value of DropdownButton(value: (use a value from the items you set)
you can not use any value you want, but it should be one of the items that you set for the DropdownMenuItem.
I think because of the update in the framework, the error came out
Here is how you can solve it
DropdownButton(
hint: const Text("Please choose your gender"),
items: <String>["Male", "Female", "Rather not say"]
.map<DropdownMenuItem<String>>((e) {
return DropdownMenuItem<String>(
value: e, child: Text(e.toString()));
}).toList(),
onChanged: (String? value) {
setState(() {
dropdownValue = value!;
});
});
Note that: dropdownValue is a string variable defined at the top
If you are loading the list from an api that returns list, look at what i did to debug the error.
Created a reusable widget that handle future response
Widget rangeLists(selectedValue) {
return FutureBuilder(
future: YourFuture,//this should return Future<List>
builder: (context, snapshot) {
if (!snapshot.hasData) {
return Text('Loading...');
} else {
List<DropdownMenuItem<String>> categoriesItems = [
DropdownMenuItem(
child: Text(selectedValue),
value: selectedValue,
),
];
print('categoriesItems.last.value');
print(categoriesItems.last.value);
var snapshotAsMap = snapshot.data as List;
for (int i = 0; i < snapshotAsMap.length; i++) {
if (snapshotAsMap[i]['category'] != selectedValue) {
categoriesItems.add(
DropdownMenuItem(
child: Text(snapshotAsMap[i]['category']),
value: snapshotAsMap[i]['category'],
),
);
}
}
return Padding(
padding: const EdgeInsets.only(left: 18.0, right: 18, top: 10),
child: Container(
padding: EdgeInsets.only(left: 25, right: 25),
decoration: BoxDecoration(
border: Border.all(color: Colors.grey, width: 1),
borderRadius: BorderRadius.circular(25)),
child: DropdownButton<String>(
items: categoriesItems,
icon: const Icon(
Icons.expand_more,
color: Colors.grey,
),
iconSize: 24,
elevation: 16,
isExpanded: true,
style: const TextStyle(color: Colors.grey),
underline: SizedBox(),
onChanged: (value) {
setState(() {
widget.selectedValue = value;
});
},
value: selectedValue,
hint: Text('My courses'),
),
),
);
}
})};
2.Usage
you can called it like this
String selectedValue="Select Here"
rangeLists(selectedValue)//call this as a widget in ur ui
It will handle all list from the Api backend when u return a list u don't need to worry about the error any more
child: DropdownButtonFormField<String>(
hint: Text(widget.hintText == "Select value..."
? "Select ${widget.caption}"
: widget.hintText),
items: getItems(),
value: **checkValue(widget.currentValue)**,
iconSize: 30,
onChanged: widget.onChanged,
),
String? **checkValue(String? value)** {
var arrRet = widget.items.where(
(item) => item[widget.valueMember].toString() == value.toString());
if (arrRet.isEmpty && widget.items.isNotEmpty)
return widget.items[0][widget.valueMember].toString();
return value;
}

control & disable a dropdown button in flutter?

I wanted to control a drop-down button and make it unclickable using a button.
Is there any way to make it disable. Basically not allowing it able to change.
new DropdownButton(
value: animalName,
items: animals.map(
(String value) {
return new DropdownMenuItem<String>(
value: value,
child: new Text('$value'),
);
},
).toList(),
onChanged: (value) {
setState(() {
animalName = value;
});
},
),
So this is the code I currently use on the drop-down button, but i cant disabled it.
Found this in the DropdownButton docs:
If items or onChanged is null, the button will be disabled, the down arrow will be grayed out, and the disabledHint will be shown (if provided)
DropdownButton(
onChanged: null,
items: [...],
)
This isn't what you want to hear, but I don't think there's currently an easy way. I experimented with simply removing all the items and that causes a nice little crash. Maybe worth raising an issue with the flutter people on github...
There is an alternative that may be good enough for you for now. If you wrap your DropdownButton in an IgnorePointer, when you want it to be disabled you can change IgnorePointer's ignoring property to true.
That way if the user taps on it, it won't do anything.
But you'll probably want to indicate to the user somehow that it's disabled as well, something like setting the hint text (as it's grey).
child: new IgnorePointer(
ignoring: true,
child: new DropdownButton(
hint: new Text("disabled"),
items: ["asdf", "wehee", "asdf2", "qwer"].map(
(String value) {
return new DropdownMenuItem<String>(
value: value,
child: new Text('$value'),
);
},
).toList(),
onChanged: (value) {},
),
You can make DropdownButtonFormField or DropdownButton disabled if set onChanged to null, and if you want that dropdown still shows selected value you must set disabledHint. For example:
DropdownButtonFormField<String>(
disabledHint: Text(_selectedItem),
value: _selectedItem,
onChanged: enabled ? (value) => setState(() => _selectedItem = value) : null,
items: items.map<DropdownMenuItem<String>>((item) {
return DropdownMenuItem(
value: item,
child: Text(item),
);
}).toList(),
)
Just wrap it with IgnorePointer widget to make DropdownButton disable
IgnorePointer(
ignoring: enabled,
child: new DropdownButton(
value: animalName,
items: animals.map(
(String value) {
return new DropdownMenuItem<String>(
value: value,
child: new Text('$value'),
);
},
).toList(),
onChanged: (value) {
setState(() {
animalName = value;
});
},
),
);
If items or onChanged is null, the button will be disabled, the down
arrow will be grayed out, and the disabledHint will be shown (if
provided)
So something like this should work:
DropdownButton<String>(
...
onChanged: this.enabled ? (id) => setState(() => this.id = id) : null,
)
okay, i found a trick that satisfied me
i wanted it hide/show the DropdownButton depending on CheckboxListTile
in StatefulWidget Class
first create a function ex:
_buildDropDown(bool enable) {
if (enable) {
return DropdownButton<String>(
hint: Text("Hint"),
items: <String>[
'item 1',
'item 2',
'item 3',
].map((String value) {
return new DropdownMenuItem<String>(
value: value,
child: new Text(value),
);
}).toList(),
onChanged: (value) {},
);
} else { // Just Divider with zero Height xD
return Divider(color: Colors.white, height: 0.0);
}
}
and now in build
bool enable = true;
#override
Widget build(BuildContext context) {
return Column(
children: <Widget>[
CheckboxListTile(
title: const Text('Switcher'),
selected: true,
value: enable,
onChanged: (bool value) {
setState(() {
enable = value;
});
},
),
_buildDropDown(enable),
],
);
}
now every time you change enable it will display and hide the DropdownButton
DropdownButtonFormField(
onChange: isDisable ? null : (str){
},
disabledHint: isDisable ? null : Text('Your hint text'),
...
)
For disable
onChange: null
For disable Caption
disabledHint: Text('Your hint text')
//add widget'AbsorbPointer' true-disable,false-enable
// isEditable = ture
AbsorbPointer(
absorbing: isEditable
DropdownButton(
onChanged: null,
items: [...],
)
)
Simple:
decoration:InputDecoration(enabled: false),