CODEWITHSUNDEEP
javajsonscalalist
Matas
Matas

Reputation: 186

Merging multiple JObjects in a list - Json4s

I am trying to merge together multiple JObjects to become one single JObject. I have a list of JObjects that I am trying to iterate over and merge each of them into one object, essentially creating one large json object.

The below works fine, however when in a list it doesn't work. I know im doing something wrong but not sure what?

val obj1: JObject = RancherHelper.convertToJObject(containers.head)
val obj2: JObject = RancherHelper.convertToJObject(containers(1))
val obj3: JObject = RancherHelper.convertToJObject(containers(2))

val x: JObject = obj1 merge obj2 merge obj3

This doesn't work:

def mergeJObjects(containers: List[JObject]): JObject = {
    val fullJsonObject: JObject = JObject()
    val singleObject = for{
      container <- containers
      fullObj = fullJsonObject.merge(container)
    } yield fullObj

    fullJsonObject
}

Upvotes: 1

Views: 1093

Answers (1)

Lasf
Lasf

Reputation: 2582

Instead of mapping over the list, fold it:

def mergeJObjects(containers: List[JObject]): JObject = {
  containers.foldLeft(JObject())((merged, next) => merged.merge(next))
}

What you have written above is syntactic sugar for this:

val fullJsonObject = JObject()
val singleObject = containers.map { container =>
  val fullObj = fullJsonObject.merge(container)
  fullObj
}
fullJsonObject

Essentially, you are mapping over the containers list, and for each container you are merging it with an empty JSON object (fullJsonObject). Therefore singleObject is no different from containers; it is a list of your original JSON objects. Moreover, since fullJsonObject is an immutable empty JObject, you are simply returning the empty JSON object at the end of your method.

Upvotes: 2

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