如何使用scala play将json对象添加到json数组中？

Question

In my scala code i have a json object consisting email data

val messages = inboxEmail.getMessages();
var jsonArray = new JsArray
for(inboxMessage <- messages)
{
    ...
    ...
    val emailJson = Json.obj("fromAddress" -> fromAddressJsonList, "toAddress" -> toAddressJsonList, "ccAddress" -> ccAddressJsonList, "bccAddress" -> bccAddressJsonList, "subject" -> emailMessage.getSubject().toString(), "message" -> Json.toJson(emailMessageBody))

I need to add emailJson to the jsonArray during each loop

i tried

jsonArray.+:(emailJson)

and

jsonArray.append(emailJson)

but getting empty array

What should i use here to add jsonObject into the json array

Answer 1

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)