Add custom validation

[mohamedalwhaidi]

How I can add custom validation, to add validation errors in another language??

[EzraBerendsen]

You can find examples in the docs: https://giancarlocode.github.io/form_bloc/#/.

For example inside the "Validation Based on other Field" tab:

final password = TextFieldBloc(
  validators: [FieldBlocValidators.required],
);
final confirmPassword = TextFieldBloc(
  validators: [FieldBlocValidators.required],
);

Validator<String> _confirmPassword(
  TextFieldBloc passwordTextFieldBloc,
) {
  return (String? confirmPassword) {
    if (confirmPassword == passwordTextFieldBloc.value) {
      return null;
    }
    return 'Must be equal to password';
  };
}

ValidationBasedOnOtherFieldFormBloc() {
  addFieldBlocs(
    fieldBlocs: [password, confirmPassword],
  );

  confirmPassword
    ..addValidators([_confirmPassword(password)])
    ..subscribeToFieldBlocs([password]);

  // Or you can use built-in confirm password validator
  // confirmPassword
  //   ..addValidators([FieldBlocValidators.confirmPassword(password)])
  //   ..subscribeToFieldBlocs([password]);
}
  }```

[frostythedev]

You can find examples in the docs: https://giancarlocode.github.io/form_bloc/#/.

For example inside the "Validation Based on other Field" tab:

final password = TextFieldBloc(
  validators: [FieldBlocValidators.required],
);
final confirmPassword = TextFieldBloc(
  validators: [FieldBlocValidators.required],
);

Validator<String> _confirmPassword(
  TextFieldBloc passwordTextFieldBloc,
) {
  return (String? confirmPassword) {
    if (confirmPassword == passwordTextFieldBloc.value) {
      return null;
    }
    return 'Must be equal to password';
  };
}

ValidationBasedOnOtherFieldFormBloc() {
  addFieldBlocs(
    fieldBlocs: [password, confirmPassword],
  );

  confirmPassword
    ..addValidators([_confirmPassword(password)])
    ..subscribeToFieldBlocs([password]);

  // Or you can use built-in confirm password validator
  // confirmPassword
  //   ..addValidators([FieldBlocValidators.confirmPassword(password)])
  //   ..subscribeToFieldBlocs([password]);
}
  }```

Can you add custom validators for an InputFieldBloc? I've been trying to figure it out for a date for like 2 weeks now

[aaassseee]

Hi, @frostythedev You can for sure. What are you difficulties? Can you show some code?

[frostythedev]

Hi, @frostythedev You can for sure. What are you difficulties? Can you show some code?

Sure, I didn't get a notification but I'm trying to validate DateTime field blocs so that they cannot be selected to a day in the past and not before other DateTime field blocs. I tried AsyncFieldValidaiton, validation based on the same field, validation based on other fields, DateTime does not seem to respond to any as it will not validate at all.

Included are the methods I tried:

` Future<DateTime?> _checkDate(DateTime? toCheck) async {
await Future.delayed(Duration(milliseconds: 500));

DateTime now = DateTime.now();

if(toCheck == null || toCheck.isAfter(toCheck)){
  return now;
}else{
  return null;
}

}
Validator<DateTime?> _dateBeforeCurrent(InputFieldBloc<DateTime?, dynamic> dateBloc) {
DateTime now = DateTime.now();

return (DateTime? dateNow){
  print('validating date');
  if(dateBloc.value!.isAfter(now)){
    print('date is good (after current)');
    return null;
  }
  print('date is not good (before current)');
  return now*//*'Date cannot be in the past'*//*;
};

}
DateTime? dateBefore(DateTime? then) {
DateTime now = DateTime.now();

 print('validating date');

 if(now.isAfter(then!)){
   print('date is not good (before current)');
   return now;
 }

 print('date is good (after current)');
 return null;

} `

[aaassseee]

@frostythedev It is hard to read and give advice without runnable code. But for the attempts that given by you, second one seems a good try. It seems you are not using the dateNow to validate.

[aaassseee]

@frostythedev It should be something like this

  Validator<DateTime?> _dateBeforeCurrent(InputFieldBloc<DateTime?, dynamic> dateBloc) {
    return (DateTime? dateTime){
      DateTime now = DateTime.now();
      print('validating date');
      if(dateBloc.value!.isAfter(now) || (dateTime?.isAfter(now) ?? false) || (dateTime?.isAfter(dateBloc.value!) ?? false)){
        print('date is good (after current)');
        return null;
      }
      print('date is not good (before current)');
      return now;
    };
  }

If you need more help, more information is needed to identify what you did wrong. A runnable example is required to let us review the code on the same page.