如何处理JSON数据中的错误不正确的节点

Question

I'm expecting following json format:

'{
  "teamId" : 9,
  "teamMembers" : [ {
    "userId" : 1000
  }, {
    "userId" : 2000
  }]
}'

If I test my code with following format:-

'{
  "teaXmId" : 9,
  "teamMembers" : [ {
    "usXerId" : 1000
  }, {
    "userXId" : 2000
  }]
}' 

I'm parsing json value as follows:-

val userId = (request.body \\ "userId" )
val teamId = (request.body \ "teamId")
val list = userId.toList
list.foreach( x => Logger.info("x val: "+x)

It doesn't throw any error to handle. Code execution goes one. Later if I try to use teamId or userId, of course it doesn't work then.

So how to check whether parsing was done correctly or stop execution right away and notify user to provide correct json format

Answer 1

If a value is not found when using \\ , then the result will be of type JsUndefined(msg) . You can throw an error immediately by making sure you have the type you expect:

 val teamId = (request.body \ "teamId").as[Int]

or:

val JsNumber(teamId) = request.body \ "teamId" //teamId will be BigDecimal

When using \\\\ , if nothing is found, then an empty List is returned, which makes sense. If you want to throw an error when a certain key is not found on any object of an array, you might get the object that contains the list and proceed from there:

val teamMembers =  (request.body \"teamMembers").as[Seq[JsValue]]

or:

val JsObject(teamMembers) = request.body \ "teamMembers"    

And then:

val userIds = teamMembers.map(v => (v \ "userId").as[Int])