Question

I am trying to add a simple string to a play session, but it is just not working. For testing I wrote a little controller function that first adds a string to the session and afterwards, it prints all elements the session contains, but it’s always empty.

def foo = Action { request =>
  request.session + ("token", "foobar")
  request.session.data.foreach{ keyVal => println("\tkey value pair: " + keyVal._1 + ", " + keyVal._2)}
  Ok("just a test")
}

What did I do wrong? Do I need to activate something via application.conf or something else?

Answer 1

Actually, a session is an immutable structure as well.

It’s true that the session object that is stored in the request one has a + method, this latter is respecting the immutability paradigm by returning a new instance of Session. Keeping the request.session unchanged.

Thinking a step further, we can assert on the fact that an updated session has only a sense when reused in another request-response transaction…

So the way to update a session is to update it while building the response (Result in Play), like that:

Ok("just a test").withSession(request.session + ("token", "foobar"))

This will add the new session field in your cookie, that will be available in the next transaction (i.e. request-response).