Converting a Scala Session Object to a Java Session Object in Play Framework

Question

Is there a way to convert the session object in scala to the session object in java in Play?

I have a Model method written in java like :

public void DoSomething(Request request, Session session)
{
       String fancyValue = request.getQueryString("userInput");
       session.put("Some Fancy Stuff",fancyValue);
}

and a Controller method written in scala like:

def showHomePage = Action { implicit request =>

     val JRequest = play.core.j.JavaHelpers.createJavaRequest(request)
     val JSession // conversion needed from request.session to play.mvc.Http.Session

     new SomeModel().DoSomething(JRequest,JSession)

     // would this include the updates done to the session in the java model?
     Ok("Testing Stuff").withSession(session) 
}

Shouldn't that be Ok("Testing Stuff").withSession(/* updated session*/), if you want to persist the session in the client? (Probably not a good idea to save too much data in the session cookie, rather use a handle to server-side cache). — Richard Close
– Richard Close, Commented Apr 9, 2014 at 11:48
@RichardClose I was focusing on something else and forgot that, will edit and include that detail, and I'm using the session to store only a simple Id, so no chance of cramming stuff into it, Thanks :) — somedev
– somedev, Commented Apr 9, 2014 at 12:22

Carsten · Accepted Answer · 2014-04-09 11:49:42Z

2

If you look at the docs of the JavaHelpers package, you'll find a function createJavaContext there. You can use that to obtain a play.mvc.Http.Context, from which you can extract a play.mvc.Http.Request and play.mvc.Http.Session.

val java_ctx = play.core.j.JavaHelpers.createJavaContext(request)
val java_request = java_ctx.request()
val java_session = java_ctx.session()

answered Apr 9, 2014 at 11:49

Carsten

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3 Comments

somedev Over a year ago

would updates to the java_session in the model hold if I return Ok("some string").withSession(session) in my controller?

Carsten Over a year ago

I'm not sure about the conversion, since the Java session is a Java HashMap, but the withSession method needs a Scala Map-like thing as parameter (that is, a sequence of (String, String) tuples. But that conversion aside, yes, they would. But as @RichardClose already mentioned in his comment, you should try to avoid putting too much stuff in there. Best practice is having just some token (a session id) inside the session cookie and do the rest on the server side.

somedev Over a year ago

I'm currently using the session only to store an Id, I understand that play uses cookies to store sessions on client side and is limited to 4KB only. I just needed to know how to convert and if updating the session in java would retain the updates in the scala controller.Thanks :)

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