How to add a json object in to a json array using scala play?

json, playframework, scala

Solution

Remember that `JsArray` is immutable, so writing

jsonArray.+:(emailJson)

will not modify `jsonArray`, it will just create a new json array with `emailJson` appended at the end.

Instead you would need to write something like:

val newArray = jsonArray +: emailJson

and use `newArray` instead of `jsonArray` afterwards.

In your case, you said you need to add an element "at each loop iteration". When using a functional language like Scala, you should probably try to think more in terms of "mapping over collections" rather than "iterating in a loop". For example you could write:

val values = messages map {inboxMessage =>
    ...
    ...
    Json.obj("fromAddress" -> fromAddressJsonList, "toAddress" -> toAddressJsonList, "ccAddress" -> ccAddressJsonList, "bccAddress" -> bccAddressJsonList, "subject" -> emailMessage.getSubject().toString(), "message" -> Json.toJson(emailMessageBody))
}
val newArray = objects ++ JsArray(values)

Problem

Original source