CODEWITHSUNDEEP
scalaplayframeworkplayframework-2.3
wrongusername
wrongusername

Reputation: 18918

Play framework Scala actions

As someone new to Scala, can someone explain the code here?

val echo = Action { request =>
  Ok("Got request [" + request + "]")
}

So I get that you're creating a new value called echo, from an Action trait (similar to a Java interface from what I can gather). request is some sort of argument, though I've never seen this syntax before -- what do the brackets and arrow => signify?

I see that I create a Result object signifying a 200 response, and presumably returning that. But what sort of function am I returning from? A constructor?

Upvotes: 1

Views: 268

Answers (2)

vzendara
vzendara

Reputation: 350

An Action is a function that takes a request and yields a result (response). Within the expression {} you have a function literal (anonymous function) request => Ok(). Thus, request will be available within the body after the =>.

Since this is Scala, the last bit of the expression evaluated will be the result; that is, what's inside Ok() will be evaluated and then you the result will be generated.

Upvotes: 1

Angelo Genovese
Angelo Genovese

Reputation: 3398

First off, the new value echo is getting its value from the result of calling the function Action.apply, where Action is an object (scala singleton, sort of related to statics in Java).

The Action.apply function apparently takes, as its argument, a function and by convention would return a value of the type of the Action trait.

{ request =>
  Ok("Got request [" + request + "]")
}

Is a function from some type (the argument is labelled request) to some type (the return of the call to Ok).

Assuming you are coming from a Java background, the Java 8 lambdas use a very similar syntax.

Upvotes: 2

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