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jsonscalaplay-json

How to build a json object given a list of fields (key -> value) in Scala

I am looking for a solution on how to create and/or append multiple fields to a play.api.libs.json.JsObject. I have a list of (string -> JsValue) in which I don't know how many there are, nor specifically which field names are available.

Json.obj does accepts multiple fields, but looks like you cannot pass in a list. Instead you need to specifically pass all the fields in like this:

Json.obj((k1 -> v1), (k2 -> v2), ...)

Which won't work for my use case. I would want something like this instead:

Json.obj(listOfFields) // listOfFields: List[(String, JsValue)]

Thank you in advance!

Solution

  • By having a look at the documentation, it's visible that JsObject companion extends (Seq[(String, JsValue)]) ⇒ JsObject, so rather than calling Json.obj (with extra conversion):

    import play.api.libs.json._

def foo(fields: List[(String, JsValue)]): JsObject = JsObject(fields)