[英]Is there a way to add a label to a DropdownButton in flutter?
我正在尝试获得这种设计: 1
[标签] : [下拉列表]
[标签] : [文本字段]
[标签] : [下拉列表]
我已经能够使用以下代码实现下拉列表:
List<String> _locations = ['Cita', 'Junta', 'Proyecto', 'Examen', 'Otro']; // Option 2
String _selectedLocation; // Option 2
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Crear Evento'),
),
body: Center(
child: Container(
width: double.infinity,
height: 400,
padding: EdgeInsets.symmetric(horizontal: 20),
alignment: Alignment.center,
child: Column(
children: <Widget>[
new Text('Categoría'),
DropdownButton(
hint: Text('Categoría'), // Not necessary for Option 1
value: _selectedLocation,
onChanged: (newValue) {
setState(() {
_selectedLocation = newValue;
});
},
items: _locations.map((location) {
return DropdownMenuItem(
child: new Text(location),
value: location,
);
}).toList(),
),
],
),
),
),
);
但是,它的输出不是我想要的方式,因为输出的格式为: 2
[标签]
PS.:我知道这不是一个正确的标签,因为它只是一个文本,如果有人能帮助我那就太好了,提前致谢。
如果我得到了你想要的东西,你将需要使用 Row( 在这里阅读更多)来做到这一点,就像下面的例子一样,使用你的代码:
List<String> _locations = ['Cita', 'Junta', 'Proyecto', 'Examen', 'Otro']; // Option 2
String _selectedLocation; // Option 2
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Crear Evento'),
),
body: Center(
child: Container(
width: double.infinity,
height: 400,
padding: EdgeInsets.symmetric(horizontal: 20),
alignment: Alignment.center,
child: Column(
children: <Widget>[
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text('Categoría'),
Container(width: 8),
DropdownButton(
hint: Text('Categoría'), // Not necessary for Option 1
value: _selectedLocation,
onChanged: (newValue) {
setState(() {
_selectedLocation = newValue;
});
},
items: _locations.map((location) {
return DropdownMenuItem(
child: new Text(location),
value: location,
);
}).toList(),
),
],
),
],
),
),
),
);
产生这个:
我知道这不是问题的答案,但是任何想要在 FormFields 中添加 labelText 的人(之前和我一样),您都可以使用InputDecorator 。
class ChecklistAddNewRepatDropdown extends StatelessWidget {
final Map<int, List> tasks;
final ChecklistAddNewState state;
final int index;
const ChecklistAddNewRepatDropdown({
Key key,
@required this.tasks,
@required this.index,
@required this.state,
}) : super(key: key);
@override
Widget build(BuildContext context) {
return InputDecorator(
decoration: (state.emptyTasks.indexOf(index) == -1)
? inputDecoration('Repeat')
: inputErrorDecoration('Repeat'),
child: DropdownButtonHideUnderline(
child: DropdownButton<String>(
value: (tasks[index] == null || tasks[index][1] == "")
? 'One'
: tasks[index][1],
isExpanded: true,
isDense: true,
style: inputTextStyle(),
icon: Icon(
Icons.arrow_drop_down,
color: Colors.black,
),
iconSize: 24,
onChanged: (value) {
if (tasks[index] != null) {
tasks[index][1] = value;
} else {
tasks[index] = ["", value];
}
checklistAddNewBloc.add(
TasksTaskWhileChangingEvent(tasks),
);
},
items: <String>['One', 'Two', 'Free', 'Four']
.map<DropdownMenuItem<String>>((String value) {
return DropdownMenuItem<String>(
value: value,
child: Text(value),
);
}).toList(),
),
),
);
你可以这样使用它。 (代码中可能有错误,我只是想举例说明如何使用InputDecorator)。
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