UI 我想建立一個表單，用來填寫出發站和目的站。但是我還沒有實作一種方法來防止用戶在 2 個欄位中填寫相同的值。這是我的代碼
Form(
key: _formKey,
child: Column(
children: [
// Stasiun Keberangkatan Form
DropdownSearch<String>(
validator: (value) {
if (value == null) {
return 'please input station';
}
return null;
},
popupProps: const PopupProps.menu(
showSelectedItems: true,
showSearchBox: true,
),
items: stationsToStName(),
dropdownDecoratorProps: DropDownDecoratorProps(
dropdownSearchDecoration: InputDecoration(
filled: true,
fillColor: const Color.fromRGBO(37, 37, 37, 0.1),
//hintText: "Stasiun keberangkatan",
hintText: "Departure Station",
hintStyle:
const TextStyle(fontFamily: 'Inter', fontSize: 14),
border: OutlineInputBorder(
borderRadius: BorderRadius.circular(5),
borderSide: const BorderSide(
width: 0,
style: BorderStyle.none,
),
),
prefixIcon: const Padding(
padding: EdgeInsets.all(8.0),
child: Image(
height: 33,
image: AssetImage(
'assets/images/icon_departureSt.png'),
),
),
),
),
onChanged: (newvalue) {
setState(() {
stKeberangkatan = newvalue!; //updated
});
},
),
const SizedBox(height: 11),
// Destination Form
DropdownSearch<String>(
validator: (value) {
if (value == null) {
return 'please input station';
}
return null;
},
popupProps: const PopupProps.menu(
showSelectedItems: true,
showSearchBox: true,
),
items: stationsToStName(),
dropdownDecoratorProps: DropDownDecoratorProps(
dropdownSearchDecoration: InputDecoration(
filled: true,
fillColor: const Color.fromRGBO(37, 37, 37, 0.1),
//hintText: "Stasiun tujuan",
hintText: "Destination Station",
hintStyle:
const TextStyle(fontFamily: 'Inter', fontSize: 14),
border: OutlineInputBorder(
borderRadius: BorderRadius.circular(5),
borderSide: const BorderSide(
width: 0,
style: BorderStyle.none,
),
),
hintMaxLines: 2,
prefixIcon: const Padding(
padding: EdgeInsets.all(11.0),
child: Image(
height: 33,
image: AssetImage(
'assets/images/icon_destinationSt.png'),
),
),
),
),
onChanged: (newvalue) {
setState(() {
stTujuan = newvalue!; //updated
});
},
),
const SizedBox(height: 35),
// "Submit" Button
SizedBox(
width: size.width,
height: 48,
child: ElevatedButton(
style: ButtonStyle(
foregroundColor:
MaterialStateProperty.all<Color>(Colors.white),
backgroundColor:
MaterialStateProperty.all<Color>(primColor),
shape: MaterialStateProperty.all<
RoundedRectangleBorder>(
RoundedRectangleBorder(
borderRadius: BorderRadius.circular(4),
side: const BorderSide(color: primColor)))),
onPressed: () {
if (_formKey.currentState != null &&
_formKey.currentState!.validate()) {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => BestRoute(
stKeberangkatan: stKeberangkatan,
stTujuan: stTujuan,
)),
);
}
},
child: const Text("Submit",
style: TextStyle(
fontFamily: 'Inter',
fontWeight: FontWeight.w700,
fontSize: 14))),
),
],
),
),
如果用戶在單擊提交按鈕時填寫相同的值，我想應用警報或驗證器
例如，用戶填寫A站為始發站和目的站。我想避免這種情況。如果用戶在單擊提交按鈕時填寫相同的值，我想應用警報或驗證程式我該如何實作？
uj5u.com熱心網友回復：
您可以創建兩個變數，一個稱為出發地，另一個稱為目的地。然后，當用戶從下拉串列中選擇一個值時，使用 setState((){}) 將該值放入變數中。最后，當用戶點擊提交按鈕時，檢查目的地和出發地的值是否不同，然后才允許用戶繼續。
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標籤：扑形式验证场地