§The Play WS API

Sometimes we would like to call other HTTP services from within a Play application. Play supports this via its play.api.libs.ws.WS library, which provides a way to make asynchronous HTTP calls.

Any calls made by play.api.libs.ws.WS should return a Promise[play.api.libs.ws.Response] which we can later handle with Play’s asynchronous mechanisms.

§Making an HTTP call

To send an HTTP request you start with WS.url() to specify the URL. Then you get a builder that you can use to specify various HTTP options, such as setting headers. You end by calling a final method corresponding to the HTTP method you want to use. For example:

val homePage: Promise[ws.Response] = WS.url("http://mysite.com").get()

Or:

val result: Promise[ws.Response] = {
  WS.url("http://localhost:9001/post").post("content")
}

§Retrieving the HTTP response result

The call is asynchronous and you need to manipulate it as a Promise[ws.Response] to get the actual content. You can compose several promises and end with a Promise[Result] that can be handled directly by the Play server:

def feedTitle(feedUrl: String) = Action {
  Async {
    WS.url(feedUrl).get().map { response =>
      Ok("Feed title: " + (response.json \ "title").as[String])
    }
  }  
}

§Post url-form-encoded data

To post url-form-encoded data a Map[String, Seq[String]] needs to be passed into post()

WS.url(url).post(Map("key" -> Seq("value")))

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