这是下拉菜单的项目列表。更改/选择项目时是否可以检索索引？这是通过API调用从Future方法接收数据的小部件。数据以显示的有益JSON文件的形式接收。
Widget _buildList() {
Size size = MediaQuery.of(context).size;
return FutureBuilder<Parameters>(
future: _futureParams,
builder: (context, snapshot) {
if (snapshot.hasData) {
return ListView.builder(
shrinkWrap: true,
itemCount: 1,
itemBuilder: (context, i) {
return Form(
key: formKey,
child: Column(
children: <Widget>[
Container(
padding: EdgeInsets.fromLTRB(40, 0, 40, 0),
height: 50.0,
child: DropdownButtonFormField<String>(
decoration: InputDecoration(
contentPadding: EdgeInsets.fromLTRB(10, 0, 10, 0),
filled: true,
fillColor: Theme.Colors.color_7,
hintText: 'Select a Profession',
hintStyle: TextStyle(fontWeight: FontWeight.bold)),
value: _listdownValue,
icon: Icon(Icons.arrow_drop_down),
iconSize: 24,
elevation: 16,
style: TextStyle(color: Colors.black),
onChanged: (String newValue) {
setState(() {
_listdownValue = newValue;
// int j =
// listAsMap.indexOf(listAsMap.where(listAsMap[i].service== newValue));
// price = listAsMap[j].price.match();
// print(price);
});
},
validator: (value) {
if (value == null) {
return "Select a Profession";
}
return null;
},
items: snapshot.data.services.map((item) {
return new DropdownMenuItem(
child: new Text(item.service),
value: item.service.toString(),
);
}).toList(),
),
),
SizedBox(
height: size.width * 0.05,
),
Container(
padding: EdgeInsets.fromLTRB(60, 0, 60, 0),
height: 50.0,
child: DropdownButtonFormField<String>(
decoration: InputDecoration(
contentPadding: EdgeInsets.fromLTRB(10, 0, 10, 0),
filled: true,
fillColor: Theme.Colors.color_7,
hintText: 'Select an Area',
hintStyle: TextStyle(fontWeight: FontWeight.bold)),
validator: (value) {
if (value == null) {
return "Select your Area";
}
print(i);
return null;
},
value: _dropdownValue,
icon: Icon(Icons.arrow_drop_down),
iconSize: 24,
elevation: 16,
style: TextStyle(color: Colors.black),
onChanged: (String newValue) {
setState(() {
_dropdownValue = newValue;
});
},
items: snapshot.data.locations.map((item) {
return new DropdownMenuItem(
child: new Text(item.subCounty ?? ''),
value: item.subCounty.toString(),
);
}).toList(),
),
),
SizedBox(
height: size.width * 0.05,
),
RaisedButton(
elevation: 5.0,
shape: new RoundedRectangleBorder(
borderRadius: new BorderRadius.circular(0.0)),
color: Theme.Colors.color_8,
child: Container(
height: 40.0,
width: 80,
child: Center(
child: const Text('Search',
style: TextStyle(
fontSize: 20,
fontWeight: FontWeight.bold,
color: Theme.Colors.color_7)),
),
),
onPressed: () async {
setState(() {
if (formKey.currentState.validate()) {
_futureSearch = createSearch(
this._dropdownValue.toString(),
this._listdownValue.toString(),
0);
saveSearch(searchP);
state = true;
}
});
print(this._listdownValue + "\ " + this._dropdownValue);
},
),
SizedBox(
height: size.width * 0.05,
),
],
),
);
},
);
}
return Container(
height: 150,
);
},
);
}
我希望在用户选择服务时获得价格。我不能直接将值设置为price，因为我还需要service的字符串值。
{
"services": [
{
"price": 3,
"service": "Caregiver"
},
{
"price": 5,
"service": "Driver"
},
{
"price": 0,
"service": "Tipper Driver"
}
],
"locations": [
{
"sub_county": "All of NY"
},
{
"sub_county": "Brkln"
}
]
}
答案 0 :(得分：0)
getDropDownMenuItems(snapshot) {
Map<int, dynamic> mapWithIndex = snapshot.data.services.asMap;
List<DropdownMenuItem> _items = [];
mapWithIndex.forEach((index, item) {
_items.add(
DropdownMenuItem<int>(
value: index,
child: Text(item.service),
),
);
});
return _items;
}
通过传递这样的快照来调用此方法
items: getDropDownMenuItems(snapshot)