New Validation

You can create a new validation by extending the Validator class. The Validator class is an abstract class that contains a method to validate the input value.

The following code shows how to create a new validation:

import 'package:validasi/validasi.dart';

class MyValidator extends Validator<String> {
  @override
  StringValidator nullable() => super.nullable();

  @override
  StringValidator custom(CustomCallback<String> callback) =>
      super.custom(callback);

  @override
  StringValidator customFor(CustomRule<String> customRule) =>
      super.customFor(customRule);
}

That's it! That's all you need to create a new validation. You can now use the MyValidator class to validate the input value.

Adding Rule

You can add a new rule by adding a new method to your class. Following the convention of Validasi, the method name should match the rule name, and the method should return the same type as the class.

The following code shows how to add a new rule to the MyValidator class:

import 'package:validasi/validasi.dart';

class MyValidator extends Validator<String> {
    MyValidator myRule() {
        addRule(
            name: 'myRule',
            test: (value) => value == 'myValue',
            message: ':name must be myValue',
        );

        return this;
    }
}

The rule will be registered using the addRule method. The addRule method requires three parameters:

• name: The name of the rule.
• test: The test function to validate the input value.
• message: The error message to return if the test function fails.

Similarly to customizing default error message you can also use :name here!

Adding Transformer Support

In order to add Transformer support to your custom validator, you can inherit the transformer property from the Validator class.

import 'package:validasi/validasi.dart';

class MyValidator extends Validator<String> {
    MyValidator({super.transformer});
}

That's it!

Using your Custom Validator

In order to use your Custom Validator just call the class like how you did it with normal Dart.

MyValidator myValidator = MyValidator();

myValidator.myRule().parse('myValue');

Your Custom Validator can also be passed to sub-type of Validator like ArrayValidator and ObjectValidator.

Validasi.array(MyValidator());

Validasi.object({
    'name': MyValidator(),
});

Adding to Validasi

Now if you want to add your custom validator to Validasi, you have to extends the Validasi class and add a new method to return your custom validator.

utils/validation.dart

import 'package:validasi/validasi.dart';

class MyValidasi extends Validasi {
    MyValidator myValidator() => MyValidator();
}

main.dart

import 'package:app/utils/validation.dart';

void main() {
    MyValidator.myValidator().myRule().parse('myValue');
}

As of currently, Dart doesn't support static method extensions, see this issue for more information.