Hi I've a question about input validation. An endpoint accepts a payload described by some data clas...

# http4k

[Nicola]

Hi I've a question about input validation.
An endpoint accepts a payload described by some data classes.
I've added a validation in a data class, like this:

data class Payment(
    val type: PaymentType,
    val amount: Float,
    val reason: String,
    val expiryDate: String,
    val code: String,
    val lisHoldingCode: String
) {
    init {
        require(reason.isNotEmpty()) { "Payment reason cannot be empty" }
        require(code.isNotEmpty()) { "Payment code cannot be empty" }
        require(lisHoldingCode.isNotEmpty()) { "Lis code cannot be empty" }
    }

Now I am writing a test to assure that validation rules are respected (ie invalid payload are not accepted).
This happens but message is too vague:

{"message":"Missing/invalid parameters","params":[{"name":"body","type":"body","datatype":"object","required":true,"reason":"Invalid"}]}

I would need a message which clearly states which parameter is wrong, using the message I've putted in the require
How can I do that?
Thanks in advance

[Nicola]

Deserialization is done through a (jackson) lens:

val jacksonPaymentRenderRequestDtoLens = Body.auto<Array<PaymentRenderRequestDto>>().toLens()
val dtos = jacksonPaymentRenderRequestDtoLens.extract(req)

Perhaps is it possible to customize these checks in the lens?

[Nicola]

(those code lines are from the function controller, the http method is a POST so payload are read from body)

[Andrew O'Hara]

I too struggle with this limitation.

[Nicola]

Not happy to hear this ...

[Andrew O'Hara]

Not to throw David under the bus, but he might know better than I

[Nicola]

We don't want David under any bus, don't we?