Ability to combine validators or validation results

[ryanofarizona]

I am using yavi to validate the properties of a Kotlin class (not arguments to a function). For some of the constraints, it is nice to use the Kotlin DSL syntax. For others (e.g., property of type List that I want to enforce constraints on each element of the list, or where I want to use a custom error message for a constraint), I can't use the Kotlin DSL.

Is there any way to combine the two validators and then call validate once? Or can I call validate on both validators and then combine the results?

Here is a simple example of the two styles of validators:

data class NestedClass(
    val id: String,
    val listOfString: List<String>,
)

val validatorUsingKotlinDsl = validator<NestedClass> {
    NestedClass::id { notBlank() }
    NestedClass::listOfString { notEmpty() }
}

val validatorNotUsingKotlinDsl = ValidatorBuilder.of<NestedClass>()
    .forEach(NestedClass::listOfString, "listOfString") { cc ->
        cc.constraint(String::toString, "") { it.notBlank() }
    }
    .build()

// some instances to test
val validNestedClass = NestedClass("valid", listOf("valid"))
val invalidNestedClassOne = NestedClass("valid", listOf(""))
val invalidNestedClassTwo = NestedClass("", listOf("valid"))
val invalidNestedClassThree = NestedClass("valid", emptyList())

// how to combine validatorUsingKotlinDsl and validatorNotUsingKotlinDsl before calling validate
// OR how to combine the results of running validatorUsingKotlinDsl.validate(instanceToTest) and validatorNotUsingKotlinDsl.validate(instanceToTest) separately

And am I correct that there is no way to provide a custom error message or message format using Kotlin DSL?

Also, I was experimenting with creating a single value validator and using liftList to apply it to a list of Strings. It works, to call validate on a list of strings, but I could not figure out how to use it as a constraint for a property that is of type List.

val listOfStringElementValidator = StringValidatorBuilder
    .of("") { it.notBlank() }
    .build()

val validListOfString = listOf("valid")
val invalidListOfString = listOf("")

// this works as expected
listOfStringElementValidator.liftList().validate(validListOfString).isValid // true
listOfStringElementValidator.liftList().validate(invalidListOfString).isValid // false

// but is there a way to reference listOfStringElementValidator or the "lifted" version of it as part of a validator for a parent class that contains a property that is of type List<String>?

[making]

I haven't used Kotlin in years and rely on contributions to add Kotlin-related features.
Pull requests are welcome.

To help me understand what you're trying to do, it would be very helpful if you could also show how you can express what you want to do in Java.

[ryanofarizona]

@making Thanks for the reply.

Here is a Java example to help ask the question better. (Please ignore that there is no reason to put these constraints in separate validators.)

Validator<ContactInfo> validatorOne = ValidatorBuilder.<ContactInfo> of()
    .nest(ContactInfo::email, "email", emailValidator)
    .build();
Validator<ContactInfo> validatorTwo = ValidatorBuilder.<ContactInfo> of()
    .nest(ContactInfo::phoneNumber, "phoneNumber", phoneNumberValidator)
    .build();

How do I do one of the following?

• Combine validatorOne and validatorTwo into one validator (after they are created separately)?
• Combine their validation results, so isValid is only true of both are true, and ConstraintViolations list is aggregation of violations from both validators

My use case is validating an instance of an already created top level class (e.g., ContactInfo), not the arguments being passed to create a new instance of the top level class

[making]

Sorry for the late response. What you want to do would probably be implemented like this:

ValueValidator<ContactInfo, ContactInfo> validator = validatorOne.applicative()
							.andThen(validatorTwo.applicative());

Validated<ContactInfo> validated = validator.validate(new ContactInfo("john@example.com", "john"));