Play 2.3 Scala - 如何在没有参考模态类的情况下验证 json

Question

I've seen many examples with pretty much everything one can need to understand how to validate json representation of a given simple model. Official play documentation is very specific on the subject, covering from simple validations to transformers and combinators.

I'm just wondering how can I check json againts a given data type structure, like:

{
  title : "title1",
  tags  : ["funny", "others"],
  props : [
    { prop1: "val1" },
    { prop2: "val2" }
  ]
}

I'd like to check the previous json example, to validate if it has this structure:

title: String
tags:  Array[String]
props: Array[(String->String]  // ???

This is of course a simplification, since a case class would be as simple as:

case class Example1(title: String, tags: Array[String], props: Array[???])

As you can see, my questions has two parts: - first, I want to properly use validation/transformation/reads or whatever API Play 2.3.x is ment to perform that kind of json validation without a model - second, how to specify an array of simple key/value objects

Answer 1

Validation with Reads does not require a model class.

val json = { ... }
val titleMustBeString: Reads[String] = (JsPath \ "title").read[String]
json.validate[String](titleMustBeString) match {
  case title: JsSuccess[String] => println(s"Title: $title")
  case err: JsError => println("Invalid json")
}