Question

I’ve got a function which loads various models, and currently have this kind of setup:

if(message == "user") {

    var model = User.findAll(

        ("room" -> "demo")

    )

} else if (message == "chat") {

    var model = Chat.findAll(

        ("room" -> "demo")

    )

}

This is really clunky as I aim to add lots more models in future, I know in javascript you can do something like this:

var models = {

    "user" : load_user,
    "chat" : load_chat

}

Where “load_user” and “load_chat” would load the respective models, and so I can streamline the whole thing by doing:

var model = models[message]();

Is there a way I can do something similar in Scala, so I can have a simple function which just passes the “message” var to a List or Object of some kind to return the relevant data?

Thanks in advance for any help, much appreciated 🙂

Answer 1

In Scala you can do:

val model = message match {
  case "user" => loadUser() // custom function
  case "chat" => loadChat() // another custom function
  case _ => handleFailure()
}

You can as well work with a Map like you did in your JavaScript example like so:

scala> def loadUser() = 1 // custom function
loadUser: Int

scala> def loadChat() = 2 // another custom function
loadChat: Int

scala> val foo = Map("user" -> loadUser _, "chat" -> loadChat _)
foo: scala.collection.immutable.Map[java.lang.String,() => Int] = Map(user -> <function0>, chat -> <function0>)

scala> foo("user")()
res1: Int = 1

Pay attention to the use of “_” in order to prevent evaluation of loadUser or loadChat when creating the map.

Personally, I’d stick with pattern matching.