kvalidation's Introduction

KValidation

Validation library for Kotlin/Java

Example:

Create the validator class by extending the generic ValidatorBase<T> class.

class UserValidator extends ValidatorBase<User> {
}

Java

User user = new User();
UserValidator validator = new UserValidator(user);

validator.forProperty(User::getName)
             .length(4)
             .mustBe(n -> n.startsWith("J"))
             .notEqual("John")
             .onError()
             .errorMessage("Name should start with J, be 4 characters in length and not be John");

ValidationResult result = validator.validate();

if (result.isValid()) {
  // woohooo
} else {
  for(ValidationError err : result.getValidationErrors()) {
    System.out.print(err.toString());
  }
}

Kotlin has even nicer syntax

val user = User()
val validator = UserValidator(user)
    
validator.forProperty { p -> p.name } rules {
    length(4)
    mustBe { n -> n.startsWith("J") }
    notEqual("John")
} onError {
    errorMessage("Name should start with J, be 4 characters in length and not be John")
}
    
val result = validator.validate()

If you don't want to create a validator class, add InnerValidator inside the validated class

class User(private val name: String, private val age: Int) {
    val validator = InnerValidator(this) setRules {
        forProperty { p -> p.name } rules {
            equal("John")
        }
    }
 }