Scala Play Json JSResultException Validation Error

Question

I am trying to pass this json string to my other method but SOMETIMES I get this error,

play.api.libs.json.JsResultException: JsResultException(errors:List((,List(ValidationError(error.expected.jsstring,WrappedArray())))))

I find it strange that this occurs randomly, sometimes I don't get the exception and sometimes I do. Any ideas?

Here is what my json looks like

val string = {
  "first_name" : {
    "type" : "String",
    "value" : "John"
  },
  "id" : {
    "type" : "String",
    "value" : "123456789"
  },
  "last_name" : {
    "type" : "String",
    "value" : "Smith"
  }
}

I read it like

(string \ "first_name").as[String]

What result do you get when you don't get an exception? Because the value of first_name field apparently is not just a string value. — maks
– maks, Commented Sep 13, 2016 at 0:07

Nagarjuna Pamu · Accepted Answer · 2016-09-13 06:44:20Z

7

(string \ "first_name") gives JsValue not JsString so as[String] does not work.

But if you need first name value you can do

val firstName = ((json \ "first_name") \ "value").as[String]

answered Sep 13, 2016 at 6:44

Nagarjuna Pamu

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Ira · Accepted Answer · 2018-07-20 02:13:33Z

1

This is another option to consider for type safety while reading and writing Json with play Json API. Below I am showing using your json as example reading part and writing is analogous.

Represent data as case classes.

case Person(id:Map[String,String], firstName:Map[String,String], lastName:[String,String]
Write implicit read/write for your case classes.

implicit val PersonReads: Reads[Person]
Employ plays combinator read API's. Import the implicit where u read the json and you get back the Person object. Below is the illustration.

val personObj = Json.fromJson[Person](json)

Please have a look here https://www.playframework.com/documentation/2.6.x/ScalaJsonAutomated

answered Jul 20, 2018 at 2:13

Ira

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Comments

Ahmed Kamoun · Accepted Answer · 2016-09-13 11:58:19Z

-3

First of all you can't traverse a String object, so your input must be converted to JsValue to be able to traverse it:

 val json = Json.parse(string)

then the first_name attribut is of JsValue type and not a String so if you try to extract the first_name value like you do you will get always a JsResultException.

I can only explain the random appearance of JsResultException by a radom change in your first_name field json structure. make sur your sting input to traverse has always a fixed first_name filed structure.

edited Sep 13, 2016 at 11:58

answered Sep 13, 2016 at 10:53

Ahmed Kamoun

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