Scalacache

The Play cache API

The default implementation of the Cache API uses EHCache. You can also provide your own implementation via a plug-in.

Accessing the Cache API

The cache API is provided by the play.api.cache.Cache object. It requires a registered cache plug-in.

Note: The API is intentionally minimal to allow several implementation to be plugged. If you need a more specific API, use the one provided by your Cache plugin.

Using this simple API you can either store data in cache:

Cache.set("item.key", connectedUser)

And then retrieve it later:

val maybeUser: Option[User] = Cache.getAs[User]("item.key")

There is also a convenient helper to retrieve from cache or set the value in cache if it was missing:

val user: User = Cache.getOrElse[User]("item.key") {
  User.findById(connectedUser)
}

How to remove the key is as follows.

// 2.0 final
Cache.set("item.key", null, 0)
// later
Cache.remove("item.key")

Caching HTTP responses

You can easily create smart cached actions using standard Action composition.

Note: Play HTTP Result instances are safe to cache and reuse later.

Play provides a default built-in helper for standard cases:

def index = Cached("homePage") {
  Action {
    Ok("Hello world")
  }
}

Or even:

def userProfile = Authenticated { user =>
  Cached(req => "profile." + user) {      
    Action { 
      Ok(views.html.profile(User.find(user)))
    }   
  }
}

Bugs

In Play 2.0, the remove method may not work as described if you are using the underlying EhCache, because Ehcache allows nulls in the cache. If you set the above method, get(key) will return Some(null). And getAs(key) will throw a NullPointerException. Google Groups Conversation.

Another workaround is:

play.api.Play.current.plugin[EhCachePlugin].map(c => c.cache.remove(key)) 

Next: Calling WebServices