I get this error:
The parameter vertical Padding can't have a value of 'null' because of its type, but the implicit default value is 'null'
This is the code:
class CustomTextFormField extends StatelessWidget {
final String hintText;
final double verticalPadding;
final String value;
final Icon suffixIcon;
final bool showLabel;
CustomTextFormField(
{this.hintText, this.verticalPadding, this.value, this.suffixIcon, this.showLabel = true});
CodePudding user response：
In the constructor it has to be marked final or passed a value to it like
CustomTextFormField(
{required this.hintText, required this.verticalPadding, required this.value, required this.suffixIcon, this.showLabel = true});
Show label has a default value if you notice and all others are required
CodePudding user response：
Try understanding null safety in Dart first : https://dart.dev/null-safety
To indicate that a parameter might have the value null, just add ? to its type declaration:
final String? hintText;
final double? verticalPadding;
final String? value;
final Icon? suffixIcon;
final bool? showLabel;
CustomTextFormField(
{this.hintText, this.verticalPadding, this.value, this.suffixIcon, this.showLabel = true});
Adding (?) nullable operator after datatype means that your parameters can be null & are optional, they don't need to be passed any values when you call your CommonTextFormField().
If you don't add (?) nullable after datatype, then all fields are required in constructor params
Like this:
final String hintText;
final double verticalPadding;
final String value;
final Icon suffixIcon;
final bool showLabel;
CustomTextFormField(
{required this.hintText, required this.verticalPadding,required this.value,required this.suffixIcon,required this.showLabel});
Named parameters are optional unless they’re explicitly marked as required.
Try this code (Includes password, mobile, email validation):
class CommonTextFormField extends StatelessWidget {
const CommonTextFormField(
{Key? key,
this.focusNode,
this.height,
this.maxLength,
this.maxLines,
this.textInputAction,
required this.hintText,
this.controller,
this.readOnly,
this.isImportantStarLabelRequired,
this.obscureText,
this.isFixedlabel,
this.isDense,
this.onSubmittedRequired,
this.autofocus,
this.isSuffixIconRequired,
this.keyboardType,
this.onChanged,
this.onTap,
this.suffixIcon,
this.labelHeading,
this.inputFormatters,
this.errorText,
this.isfilled = false,
this.textAlign,
this.textAlignVertical,
this.hintStyle,
this.customDateError,
this.isMobileValidationRequired,
this.isEmailValidationRequired,
this.isPasswordValidationRequired,
this.compareWithcontroller,
this.compareWithPrevious = false,
this.compareErrorText})
: super(key: key);
final FocusNode? focusNode;
final TextAlign? textAlign;
final TextAlignVertical? textAlignVertical;
final TextStyle? hintStyle;
final double? height;
final int? maxLength;
final int? maxLines;
final TextInputAction? textInputAction;
final String hintText;
final String? errorText;
final String? compareErrorText;
final TextEditingController? controller;
final TextEditingController? compareWithcontroller;
final bool? readOnly;
final bool? isImportantStarLabelRequired;
final bool? obscureText;
final bool? isFixedlabel;
final bool? isDense;
final bool? onSubmittedRequired;
final bool? isfilled;
final bool? isMobileValidationRequired;
final bool? isEmailValidationRequired;
final bool? isPasswordValidationRequired;
final bool? customDateError;
final bool? autofocus;
final bool? compareWithPrevious;
final bool? isSuffixIconRequired;
final TextInputType? keyboardType;
final void Function(String)? onChanged;
final void Function()? onTap;
final Widget? suffixIcon;
final String? labelHeading;
final List<TextInputFormatter>? inputFormatters;
@override
Widget build(BuildContext context) {
final themeViewModel = context.watch<ThemeViewModel>();
final baseTextTheme = themeViewModel.baseTextTheme;
final baseColorTheme = themeViewModel.colors;
bool error = false;
return TextFormField(
autovalidateMode: AutovalidateMode.onUserInteraction,
autofocus: autofocus ?? false,
focusNode: focusNode,
maxLength: maxLength,
maxLines: maxLines ?? 1,
readOnly: readOnly ?? false,
onTap: onTap,
keyboardType: keyboardType ?? TextInputType.text,
textInputAction: textInputAction ?? TextInputAction.next,
controller: controller,
obscureText: obscureText ?? false,
inputFormatters: inputFormatters,
onChanged: onChanged,
onFieldSubmitted: onSubmittedRequired == true
? (_) => FocusScope.of(context).nextFocus()
: null,
style: baseTextTheme.hintValueTextStyle,
textCapitalization: TextCapitalization.sentences,
textAlign: textAlign ?? TextAlign.start,
textAlignVertical: textAlignVertical,
decoration: InputDecoration(
// fillColor: baseColorTheme.primaryColor,
// focusColor: Colors.white,
errorMaxLines: 2,
contentPadding:
const EdgeInsets.symmetric(horizontal: 10, vertical: 12),
suffixIcon: isSuffixIconRequired == true ? suffixIcon : null,
suffixIconConstraints:
const BoxConstraints(minWidth: 20, minHeight: 20),
// helperText: " ",
// helperStyle: const TextStyle(fontSize: 0),
isDense: true,
hintText: hintText,
hintStyle: hintStyle ?? baseTextTheme.loginTextFieldHintTextStyle,
errorStyle: TextStyle(
fontSize: 13,
fontFamily: 'Avenir',
color: baseColorTheme.textFieldFloatingLabelStarColor),
// errorStyle: focusNode.hasFocus
// ? const TextStyle(fontSize: 0, height: 0)
// : TextStyle(
// fontSize: 13,
// fontFamily: 'Avenir',
// color: baseColorTheme.textFieldFloatingLabelStarColor),
floatingLabelBehavior:
isFixedlabel == true ? FloatingLabelBehavior.always : null,
label: labelHeading != null
? RichText(
text: TextSpan(children: [
TextSpan(
text: labelHeading,
style: baseTextTheme.loginTextFieldFloatingLabelTextStyle,
),
if (isImportantStarLabelRequired == true)
TextSpan(
text: " *",
style: baseTextTheme
.loginTextFieldFloatingLabelStarTextStyle),
]))
: null,
focusedErrorBorder: OutlineInputBorder(
borderSide: BorderSide(
color: baseColorTheme.textFieldFloatingLabelStarColor)),
errorBorder: (controller != null && controller!.text.isNotEmpty)
? null
: OutlineInputBorder(
borderSide: BorderSide(
color: baseColorTheme.textFieldFloatingLabelStarColor)),
focusedBorder: const OutlineInputBorder(
borderSide: BorderSide(color: Colors.black)),
enabledBorder: OutlineInputBorder(
borderSide:
BorderSide(color: baseColorTheme.textfieldInputBorderColor)),
border: OutlineInputBorder(
borderSide:
BorderSide(color: baseColorTheme.textfieldInputBorderColor))),
validator: (value) {
value!.trim().isNotEmpty ? error = !error : error = error;
if (customDateError == true) {
if (value.toLowerCase() == hintText.toLowerCase()) {
return errorText;
}
}
if (value.isEmpty) {
return errorText;
}
if (compareWithPrevious == true) {
if (compareWithcontroller != null) {
if (value != compareWithcontroller!.text) {
return compareErrorText ??
'Make sure your field matches with above';
}
}
}
if (isMobileValidationRequired == true) {
if (value.length > 10 || value.length < 10) {
return "Please Enter Valid Mobile Number";
}
}
if (isEmailValidationRequired == true) {
if (!RegExp(
r'^(([^<>()[\]\\.,;:\s@\"] (\.[^<>()[\]\\.,;:\s@\"] )*)|(\". \"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9] \.) [a-zA-Z]{2,}))$')
.hasMatch(value)) {
return "Please Enter Valid Email ID";
}
}
if (isPasswordValidationRequired == true) {
if (!RegExp(
r'^(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])(?=.*?[!@#\$&*~]).{6,}$')
.hasMatch(value)) {
return "Please enter a strong password of atleast 6 characters ( for eg. Name@1234 )";
}
}
return null;
},
);
}
}