Play Framework WS: Returning JSON data as Int

Question

i was trying out the code from this site (with a little modification) and i ran into a problem returning the result as an Int.

class NeoService(rootUrl: String) {
    def this() = this("http://default/neo/URL/location/db/data")


    val stdHeaders = Seq(
        ("Accept", "application/json"), 
        ("Content-Type", "application/json") 
    )

    def executeCypher(query: String, params: JsObject) : Future[Response] = {
        WS.url(rootUrl + "/cypher").withHeaders(stdHeaders:_*).post(Json.obj(
            "query" -> query,
            "params" -> params
        ))
    }

    def findNode(id: Int) : Future[Option[Int]] = {
        val cypher = """
          START n=node({id})
          RETURN id(n) as id
       """.stripMargin

        val params = Json.obj("id" -> id)

        for (r <- executeCyhper(cypher, params)) yield {
            val data = (r.json \ "data").as[JsArray]
            if (data.value.size == 0)
               None
            else
               Some(data.value(0).as[JsArray].value(0).as[Int])
        }
    }
}

if i pass a valid id into findNode() it gives me this error:

[JsResultException: JsResultException(errors:List((,List(ValidationError(validate.error.expected.jsnumber,WrappedArray())))))]

at the line Some(data.value(0).as[JsArray].value(0).as[Int]) and if i pass an id that does not exist, it gives me this error:

[JsResultException: JsResultException(errors:List((,List(ValidationError(validate.error.expected.jsarray,WrappedArray())))))]

at the line val data = (response.json \ "data").as[JsArray]

if i just pass an Int like this:

... else 
        Some(10)...

it works fine. i have no idea what's going on and the what the error message is trying to tell me.

score 5 · Accepted Answer · answered Aug 01 '13 at 12:13

What this message is telling you is that the JSON your providing is not parseable in the type you expect.

The first one is about Some(data.value(0).as[JsArray].value(0).as[Int]). apparently data.value(0).as[JsArray].value(0) is not a Number, and therefore can't be converted to an Int.

For the second one, val data = (response.json \ "data").as[JsArray] since the id does not exist, apparently the Json you get has no key 'data', or the value at that key is not an array (null ?).

I suggest you log the value of r.json before parsing. You'll see exactly why it's failing. You should also avoid using as and use validate instead (http://www.playframework.com/documentation/2.1.2/ScalaJsonRequests).

Play Framework WS: Returning JSON data as Int

1 Answers1