[2.2-Scala] Future how to print out Response (plain/text)?

[Justin Maat]

Hi all,

I'm pretty new to Scala and Play, so sorry if this is a dumb question.  I'm trying to call a webservice and print out the entire response to the console but can't seem to figure it out.  The response should be coming back as plain/text and all the examples I've seen are for examples to validate JSON that's been serialized back into an object.

My code (note this is inside a junit test): 

    val holder : WSRequestHolder = WS.url("http://mydomain.com/")
    val futureResponse : Future[Response] = holder.get()

How exactly can I read the response back and print out the full text?  I've seen ways use .map on the Response objects, but I'm still a bit confused.

One method i've tried, but not sure where to put the println statement.  In this case, I know the webservice returns back a plain/text so I've used String with the Future

    val futureResult: Future[String] = WS.url("http://mydomain/").get().map {
      response =>
        response.xml.text   //should this be response.body?  How can I print this out?
    }

In java, I would normally use something like JaxRS to get the response as an InputStream, load it into a String, then print that out.  I'm not sure if that's the best method in Scala, or if there's an easier way.

I feel like I've overlooked something simple.  Any ideas?

[Justin Maat]

So, apparently I missed the entire section on the api  scala.concurrent.Await

Also, I found the correct way to get the full body text was response.body

Sorry, not sure how I missed these.  The full implementation below..

    val futureResult: Future[String] = WS.url("http://mydomain.com").get().map {
      response =>
        response.body
    }


    //arbitrary 5 seconds
    val result = Await.result(futureResult, 5 seconds)


    println(result)  

[Ryan Tanner]

You really shouldn't use Await, you're just setting yourself up for performance problems down the road.  Your first example would've worked find if you replaced "response.xml.text" with "println(response.body)"

[Justin Maat]

Hi Ryan,

Thanks for your suggestion on avoiding Await.  I'll take a look into it more.

But I don't quite follow the idea to replace response.xml.text  with println(response.body).  I'm returning a Future[String] , so I don't think I can just print out the statement in that block (unless I'm missing something?) 

For example 

    val futureResult: Future[String] = WS.url("http://mydomain.com/").get().map {
      response =>
        println(response.body)    //compile error bc it's not returning a String
    }

I also tried using a callback, but couldn't quite figure out the correct code.

    val futureResult = WS.url("http://mydomain.com/").get().map {
      response =>
        response.body
    }
   
    //would this work?  if so, what would I put here?
    futureResult.onSuccess{
      return println("successful")  //this prints, but I can't figure out how to get the body in here
    }

[Christopher Hunt]

Treat Await as a code smell. :-)

[Justin Maat]

Ok, thanks for the tip, this makes sense actually.  I still have more to read; but if I'm understanding correctly Await will actually block execution until it completes or the duration time is met (in my example above, 5 seconds).

So, I've tried the code below but it still won't work.  The reason looks to be that the execution is completing before the Webservice Result has a chance to send the data back.  This would make sense since I'm running this code block from a junit test method.  In my controllers and/or other code, this won't be an issue since the web app will always be running.

    val futureResult: Future[String] = WS.url("http://mydomain.com/").get().map {
      response =>

        response.body
    }
     
    futureResult onComplete{
      case Success(body) => return println(body)
      case Failure(error) => return println(error)
    }

When I try adding a Thread.sleep() , I can get the printout to occur successfully (similar to Await), but this is obviously blocking the thread as well.  

    val futureResult: Future[String] = WS.url(myurl).get().map {
      response =>
        response.body
    }
     
    futureResult onComplete{
      case Success(body) => return println(body) //prints successfully now, bc it has up to 1 sec to run the above
      case Failure(error) => return println(error)
    }
   
    Thread.sleep(1000)

Looks like I have some learning todo on how to properly test asynchronous logic in Junit :)

Thanks for the help!