如何在Flutter中将验证器传递给“ TextFormField”? [英] How to pass a validator to the `TextFormField' in Flutter?
问题描述
我正在Flutter应用程序中为表单动态生成文本字段。请检查以下代码
I am dynamically generating textfields for my forms, in my flutter app. Please check below code
Widget _buildInputFields(
String label,
TextEditingController textController,
TextInputType textInputType,
IconData icon,
Color iconColor,
) {
return Container(
margin: EdgeInsets.only(left: 20, bottom: 20),
child: Container(
padding: EdgeInsets.only(right: 20),
child: Row(
children: <Widget>[
Flexible(
child: TextFormField(
controller: textController,
validator: (value) {
if (value.isEmpty) {
return 'Please enter some text';
}
},
style: new TextStyle(color: Colors.white),
keyboardType: textInputType,
decoration: InputDecoration(
labelText: label,
fillColor: Colors.white,
labelStyle: TextStyle(
color: Colors.white, fontWeight: FontWeight.w600),
enabledBorder: OutlineInputBorder(
borderSide:
const BorderSide(color: Colors.white30, width: 2.0),
borderRadius: BorderRadius.circular(25.0),
),
suffixIcon: IconButton(
icon: Icon(icon, color: iconColor),
onPressed: () {},
)),
),
),
],
),
));
}
上述方法返回 TextFormField
具有所需的样式,因此我不必将其重新编码数百次。我只是调用该方法,然后得到一个新的 TextFormField
The above method returns a TextFormField
with the styling I need, so I don't have to recode it hundreds of times. I just call the method and I get a new TextFormField
无论如何,我需要进行表单验证和每个字段具有不同的验证。在Flutter中,如何将 validator
传递给 textformfield
?
Anyway, I need to do form validation and every field has a different validation.In flutter, how can I pass a validator
to the textformfield
?
推荐答案
您可以像传递给其他验证者一样简单地将验证器作为参数传递。您需要做的就是传递一个将String作为参数并返回String的函数。
You can simply pass the validator as an argument just as you have done to the others. All you need is to pass in a function that takes a String as an argument and returns a String too.
//username validator possible structure
Function(String) usernameValidator = (String username){
if(username.isEmpty){
return 'Username empty';
}else if(username.length < 3){
return 'Username short';
}
return null;
};
//password validator possible structure
passwordValidator(String password){
if(password.isEmpty){
return 'Password empty';
}else if(password.length < 3){
return 'PasswordShort';
}
return null;
}
//new build function
Widget _buildInputFields(
String label,
TextEditingController textController,
TextInputType textInputType,
IconData icon,
Color iconColor,
String Function(String) validator
) {
return Container(
margin: EdgeInsets.only(left: 20, bottom: 20),
child: Container(
padding: EdgeInsets.only(right: 20),
child: Row(
children: <Widget>[
Flexible(
child: TextFormField(
controller: textController,
validator: validator,
style: new TextStyle(color: Colors.white),
keyboardType: textInputType,
decoration: InputDecoration(
labelText: label,
fillColor: Colors.white,
labelStyle: TextStyle(
color: Colors.white, fontWeight: FontWeight.w600),
enabledBorder: OutlineInputBorder(
borderSide:
const BorderSide(color: Colors.white30, width: 2.0),
borderRadius: BorderRadius.circular(25.0),
),
suffixIcon: IconButton(
icon: Icon(icon, color: iconColor),
onPressed: () {},
)),
),
),
],
),
));
}
//calling your function
_buildInputFields(label, textController, textInputType, icon, iconColor, usernameValidator);
_buildInputFields(label, textController, textInputType, icon, iconColor, passwordValidator);
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