Dfyjkt

I have a json file and contains some currency value. I use rootBundle.loadString to load my json data.
Now I need to load the DropdownButton with using my jsonData. DropdownButton text must shows the json value such as "TRL”. But if I try to select any of the menu item I need to save the value like TRL_00. My dropdownbutton is not working in my code.My question is

How do I load type json file into dropdown DropdownButton?

this part is not working:

items: _mapCurrency((String value) 
 return new DropdownMenuItem<String>(
 value: value,
 child: new Text(value),
 );
 ).toList(),

My son file:

 "00": "TRL",
 "01": "USD",
 “02”: "GBP",
 “03”: "EUR"

Load json:

Map _mapCurrency;
String _currency;

String jsonCurrency =
await rootBundle.loadString("packages/currencies.json");
_mapCurrency = json.decode(jsonCurrency);

DropDown part:

new FormField<String>(
 builder: (FormFieldState<String> state) 
 return InputDecorator(
 decoration: InputDecoration(
 labelText: ‘Currency’,
 labelStyle: TextStyle(
 fontSize: 18.0,
 fontWeight: FontWeight.bold,
 color: Colors.green.shade700),
 errorText: state.hasError ? state.errorText : null,
 ),
 isEmpty: _currency == '',
 child: new DropdownButtonHideUnderline(
 child: new DropdownButton<String>(
 style: TextStyle(
 fontSize: 18.0,
 color: Colors.black,
 fontWeight: FontWeight.w500,
 ),
 value: _currency,
 isDense: true,
 onChanged: (String newValue) 
 setState(() 
 _currency = newValue;
 state.didChange(newValue);
 );
 ,
 items: _mapCurrency((String value) 
 return new DropdownMenuItem<String>(
 value: value,
 child: new Text(value),
 );
 ).toList(),
 ),
 ),
 );
 ,
 validator: (val) 
 return val != '' ? null : ‘Choose a Currency…’;
 ,
),

I asked other question in here How do I load my local json into List<Map> variable?. And help of Günter Zöchbauer I finally finished the steps in my project. Complete code is here.

This my local json.

[
 “id”: 00”, “name”: ”TRL”,
 “id”: 01”, “name”: ”USD”,
 “id”: 02”, “name”: ”GBP”,
 “id”: 03”, “name”: ”EUR”,
]




class _MyHomePageState extends State<MyHomePage> 
 final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();
 final GlobalKey<FormState> _formKey = new GlobalKey<FormState>();

 String _mySelectedCurrency;
 List<Map> _myCurrencies;

 @override
 void initState() 
 // TODO: implement initState
 super.initState();
 _loadLocalJsonData();
 

 Future _loadLocalJsonData() async 
 String jsonCurrency = await rootBundle
 .loadString("packages/capi/tcbank.json");
 setState(() 
 _myCurrencies = List<Map>.from(jsonDecode(jsonCurrency) as List);
 print("*******_myCurrencies: $_myCurrencies");
 );
 

 @override
 Widget build(BuildContext context) 
 return _myCurrencies == null ? _buildWait(context) : _buildRun(context);
 

 // TODO: BUILD RUN
 Widget _buildRun(BuildContext context) 
 final _itemsName = _myCurrencies.map((c) 
 return new DropdownMenuItem<String>(
 value: c["id"].toString(),
 child: new Text(c["name"].toString()),
 );
 ).toList();

 return new Scaffold(
 key: _scaffoldKey,
 body: new SafeArea(
 top: false,
 bottom: false,
 child: new Form(
 key: _formKey,
 child: new ListView(
 padding: const EdgeInsets.symmetric(
 horizontal: 16.0, vertical: 32.0),
 children: <Widget>[
 //TODO: CURRENCY #########################
 new FormField<String>(
 builder: (FormFieldState<String> state) 
 return InputDecorator(
 decoration: InputDecoration(
 labelText: 'CHOOSE CURRENCY',
 labelStyle: TextStyle(
 fontSize: 18.0,
 fontWeight: FontWeight.bold,
 color: Colors.green.shade700),
 errorText: state.hasError ? state.errorText : null,
 ),
 isEmpty: _mySelectedCurrency == '',
 child: new DropdownButtonHideUnderline(
 child: new DropdownButton<String>(
 isExpanded: true,
 style: TextStyle(
 fontSize: 14.0,
 color: Colors.black,
 fontWeight: FontWeight.w500,
 ),
 value: _mySelectedCurrency,
 isDense: true,
 onChanged: (String newValue) 
 setState(() 
 _mySelectedCurrency = newValue;
 state.didChange(newValue);
 );
 ,
 items: _itemsName,
 ),
 ),
 );
 ,
 validator: (val) 
 return val != '' ? null : 'Choose Currency...';
 ,
 ),
 ],
 ))));
 

 // TODO: BUILD WAIT
 Widget _buildWait(BuildContext context) 
 return new Scaffold(
 body: new Center(child: CircularProgressIndicator()),
 );