Intercept phoenix json response

I’m looking for a correctly way to intercept, via plug, a phoenix controller that returns a json response body and modify its body (putting more info on json object), before been converted to iodata/string.

Is that possible? I look into phoenix source, at Phoenix.View.render, and looks like there is no way…

What I really want to do: take advantage of the request to “inject” an updated current_user fields to my client app, without need another request or websocket.

thanks for any help!