如何在play framework 2.1中保留对象

Question

my problem is that I need to preserve a list of objects that were obtained from an A controller , this controller to send the ID of objects and some basic data of these in VIEW , in the view I need to select an row (depicting an object in the list) to be stored in a database, then this ID is taken to a controller B which calls the list of objects preserved and is obtained for selected object in the database then save.

    Controller A{

     List<X> listX = math_function();
     return ok( _view.render(listX)); 

    }

    view.scala.html

    @for(listX -> X){
      <td id="@x.id"> @x.name</td>
    }

    Controller B{
...
     listX = getPreserveLists();
     x = ListX.get(get_id);
     x.save()
...
    }

I would like to know how to preserve these objects. Thanks.

Answer 1

You can preserve them into KVM(like redis ) but I don't recommend the way because you compute them in controller, means it does not takes much time. So, you should compute them every time.

If math_function takes huge time, you should not do them in controller. Do it out of http request(like batch) and store results in DB, KVM, etc... or Memoize the function.

Answer 2

One option is to use the play.api.cache.Cache object described here .

You could store data in the cache:

// if listX could be different for every user, 
// you could use user.login as a key
Cache.set(user.login, listX) 

And then you could retrieve listX later:

val maybeLisX: Option[List[X]] = Cache.getAs[List[X]](user.login)

I would like to add that this is only worth doing if computing listX is an expensive operation. You definitely don't want to do this if listX could be different for the same input. In that case, you should recompute listX.