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tweetmap's Introduction

TweetMap Workshop

Setup

  1. Install Activator: Copy the zip file to your computer, extract the zip, double-click on the activator or activator.bat file to launch the Activator UI

  2. Create a new app with the Play Scala Seed template

  3. Optional: Open the project in an IDE: Select Code then Open then select your IDE and follow the instructions to generate the project files and open the project in Eclipse or IntelliJ

Reactive Requests

  1. Create a new route in conf/routes:

     GET        /tweets               controllers.Application.search(query: String)
    
  2. Create a new reactive request handler in app/controllers/Application.scala:

     import play.api.Play.current
     import play.api.libs.concurrent.Execution.Implicits.defaultContext
     import play.api.libs.json._
     import play.api.libs.ws.WS
     import play.api.mvc._
     
     import scala.concurrent.Future
    
       def index = Action {
         Ok(views.html.index("TweetMap"))
       }
     
       def search(query: String) = Action.async {
         fetchTweets(query).map(tweets => Ok(tweets))
       }
     
       def fetchTweets(query: String): Future[JsValue] = {
         val tweetsFuture = WS.url("http://search-twitter-proxy.herokuapp.com/search/tweets").withQueryString("q" -> query).get()
         tweetsFuture.map { response =>
           response.json
         } recover {
           case _ => Json.obj("responses" -> Json.arr())
         }
       }
    
  3. Test it: http://localhost:9000/tweets?query=typesafe

Test the Controller

  1. Update the test/ApplicationSpec.scala file with these tests:

     import org.specs2.mutable._
     import org.specs2.runner._
     import org.junit.runner._
     
     import play.api.libs.json.JsValue
     import play.api.test._
     import play.api.test.Helpers._
    
    
       "Application" should {
     
    
         "send 404 on a bad request" in new WithApplication{
           route(FakeRequest(GET, "/boum")) must beNone
         }
     
         "render index template" in {
           val html = views.html.index("Coco")
     
           contentAsString(html) must contain("Coco")
         }
     
         "render the index page" in new WithApplication{
           val home = route(FakeRequest(GET, "/")).get
     
           status(home) must equalTo(OK)
           contentType(home) must beSome.which(_ == "text/html")
           contentAsString(home) must contain ("TweetMap")
         }
     
         "search for tweets" in new WithApplication {
           val search = controllers.Application.search("typesafe")(FakeRequest())
     
           status(search) must equalTo(OK)
           contentType(search) must beSome("application/json")
           (contentAsJson(search) \ "statuses").as[Seq[JsValue]].length must beGreaterThan(0)
         }
         
       }
    
  2. Run the tests

Bootstrap UI

  1. Add WebJar dependency to build.sbt:

     "org.webjars" % "bootstrap" % "2.3.1"
    
  2. Restart Play

  3. Delete public/stylesheets

  4. Create a app/assets/stylesheets/main.less file:

     body {
       padding-top: 50px;
     }
    
  5. Update the app/views/main.scala.html file:

     <link rel='stylesheet' href='@routes.Assets.at("lib/bootstrap/css/bootstrap.min.css")'>
     
     
     <body>
         <div class="navbar navbar-fixed-top">
             <div class="navbar-inner">
                 <div class="container-fluid">
                     <a href="#" class="brand pull-left">@title</a>
                 </div>
             </div>
         </div>
         <div class="container">
             @content
         </div>
     </body>
    
  6. Update the app/views/index.scala.html file:

     @(message: String)
     
     @main(message) {
     
         hello, world
     
     }
    
  7. Run the app and make sure it looks nice: http://localhost:9000

AngularJS UI

  1. Add WebJar dependency to build.sbt:

     "org.webjars" % "angularjs" % "1.2.16"
    
  2. Enable AngularJS in the app/views/main.scala.html file:

     <html ng-app="myApp">
     
     
     <script src="@routes.Assets.at("lib/angularjs/angular.min.js")"></script>
     <script type='text/javascript' src='@routes.Assets.at("javascripts/main.js")'></script>
    
  3. Update the app/views/main.scala.html file replacing the contents of <body> with:

     <div class="container-fluid" ng-controller="Search">
         <a href="#" class="brand pull-left">@title</a>
         <form class="navbar-search pull-left" ng-submit="search()">
             <input ng-model="query" class="search-query" placeholder="Search">
         </form>
     </div>
    
  4. Replace the app/views/index.scala.html file:

     @(message: String)
     
     @main(message) {
     
         <div ng-controller="Tweets">
             <ul>
                 <li ng-repeat="tweet in tweets">{{tweet.text}}</li>
             </ul>
         </div>
     
     }
    
  5. Create a new file app/assets/javascripts/main.js containing:

     var app = angular.module('myApp', []);
     
     app.factory('Twitter', function($http, $timeout) {
         
         var twitterService = {
             tweets: [],
             query: function (query) {
                 $http({method: 'GET', url: '/tweets', params: {query: query}}).
                     success(function (data) {
                         twitterService.tweets = data.statuses;
                     });
             }
         };
         
         return twitterService;
     });
     
     app.controller('Search', function($scope, $http, $timeout, Twitter) {
     
         $scope.search = function() {
             Twitter.query($scope.query);
         };
     
     });
     
     app.controller('Tweets', function($scope, $http, $timeout, Twitter) {
     
         $scope.tweets = [];
         
         $scope.$watch(
             function() {
                 return Twitter.tweets;
             },
             function(tweets) { 
                 $scope.tweets = tweets;
             }
         );
         
     });
    
  6. Restart the Play app

  7. Run the app, make a query, and verify the tweets show up: http://localhost:9000

WebSocket

  1. Create a new route in conf/routes:

     GET        /ws                   controllers.Application.ws
    
  2. Add a new controller method in app/controllers/Application.scala:

       import actors.UserActor
       import akka.actor.Props
       import play.api.libs.json.JsValue
       import play.api.mvc.WebSocket
    
       def ws = WebSocket.acceptWithActor[JsValue, JsValue] { request => out =>
         Props(new UserActor(out))
       }
    
  3. Create an Actor in app/actors/UserActor.scala containing:

     package actors
     
     import akka.actor.{Actor, ActorRef}
     import akka.pattern.pipe
     import controllers.Application
     import play.api.libs.concurrent.Execution.Implicits.defaultContext
     import play.api.libs.json.JsValue
     
     import scala.concurrent.duration._
     
     class UserActor(out: ActorRef) extends Actor {
     
       var maybeQuery: Option[String] = None
     
       val tick = context.system.scheduler.schedule(Duration.Zero, 5.seconds, self, FetchTweets)
     
       def receive = {
     
         case FetchTweets =>
           maybeQuery.foreach { query =>
             Application.fetchTweets(query).pipeTo(out)
           }
     
         case message: JsValue =>
           maybeQuery = (message \ "query").asOpt[String]
     
       }
     
       override def postStop() {
         tick.cancel()
       }
     
     }
     
     case object FetchTweets
    
  4. Update the app.factory section of app/assets/javascripts/main.js with:

     var ws = new WebSocket("ws://localhost:9000/ws");
     
     var twitterService = {
         tweets: [],
         query: function (query) {
             $http({method: 'GET', url: '/tweets', params: {query: query}}).
                 success(function (data) {
                     twitterService.tweets = data.statuses;
                 });
             ws.send(JSON.stringify({query: query}));
         }
     };
     
     ws.onmessage = function(event) {
         $timeout(function() {
             twitterService.tweets = JSON.parse(event.data).statuses;
         });
     };
     
     return twitterService;
    

Test the Actor

  1. Add akka-testkit to the dependencies in build.sbt:

     "com.typesafe.akka" %% "akka-testkit" % "2.3.3" % "test"
    
  2. Regenerate the IDE project files to include the new dependency

  3. Create a new file in test/UserActorSpec.scala containing:

     import actors.UserActor
     import akka.testkit.{TestProbe, TestActorRef}
     import org.specs2.mutable._
     import org.specs2.runner._
     import org.specs2.time.NoTimeConversions
     import org.junit.runner._
     
     import play.api.libs.concurrent.Akka
     import play.api.libs.json.{JsValue, Json}
     import play.api.test._
     
     import scala.concurrent.duration._
     
     
     @RunWith(classOf[JUnitRunner])
     class UserActorSpec extends Specification with NoTimeConversions {
     
       "UserActor" should {
     
         "fetch tweets" in new WithApplication {
     
           //make the Play Application Akka Actor System available as an implicit actor system
           implicit val actorSystem = Akka.system
     
           val receiverActorRef = TestProbe()
     
           val userActorRef = TestActorRef(new UserActor(receiverActorRef.ref))
     
           val querySearchTerm = "scala"
           val jsonQuery = Json.obj("query" -> querySearchTerm)
     
           // send the query to the Actor
           userActorRef ! jsonQuery
     
           // test the internal state change
           userActorRef.underlyingActor.maybeQuery.getOrElse("") must beEqualTo(querySearchTerm)
     
           // the receiver should have received the search results
           val queryResults = receiverActorRef.expectMsgType[JsValue](10.seconds)
           (queryResults \ "statuses").as[Seq[JsValue]].length must beGreaterThan(1)
         }
       }
     }
    
  4. Run the tests

Add the Tweet Map

  1. Add a new dependency to the build.sbt file:

     "org.webjars" % "angular-leaflet-directive" % "0.7.6"
    
  2. Restart the Play app

  3. Include the Leaflet CSS and JS in the app/views/main.scala.html file:

     <link rel='stylesheet' href='@routes.Assets.at("lib/leaflet/leaflet.css")'>
     <script type='text/javascript' src='@routes.Assets.at("lib/leaflet/leaflet.js")'></script>
     <script type='text/javascript' src='@routes.Assets.at("lib/angular-leaflet-directive/angular-leaflet-directive.min.js")'></script>
    
  4. Replace the <ul> in app/views/index.scala.html with:

     <leaflet width="100%" height="500px" markers="markers"></leaflet>
    
  5. Update the first line of the app/assets/javascripts/main.js file with the following:

         var app = angular.module('myApp', ["leaflet-directive"]);
    
  6. Update the app.controller('Tweets' section of the app/assets/javascripts/main.js file with the following:

         $scope.tweets = [];
         $scope.markers = [];
         
         $scope.$watch(
             function() {
                 return Twitter.tweets;
             },
             function(tweets) { 
                 $scope.tweets = tweets;
                 
                 $scope.markers = tweets.map(function(tweet) {
                     return {
                         lng: tweet.coordinates.coordinates[0],
                         lat: tweet.coordinates.coordinates[1],
                         message: tweet.text,
                         focus: true
                     };
                 });
             }
         );
    
  7. Create new functions in app/controllers/Application.scala to get (or fake) the location of the tweets:

       private def putLatLonInTweet(latLon: JsValue) = __.json.update(__.read[JsObject].map(_ + ("coordinates" -> Json.obj("coordinates" -> latLon))))
     
       private def tweetLatLon(tweets: Seq[JsValue]): Future[Seq[JsValue]] = {
         val tweetsWithLatLonFutures = tweets.map { tweet =>
     
           if ((tweet \ "coordinates" \ "coordinates").asOpt[Seq[Double]].isDefined) {
             Future.successful(tweet)
           } else {
             val latLonFuture: Future[(Double, Double)] = (tweet \ "user" \ "location").asOpt[String].map(lookupLatLon).getOrElse(Future.successful(randomLatLon))
             latLonFuture.map { latLon =>
               tweet.transform(putLatLonInTweet(Json.arr(latLon._2, latLon._1))).getOrElse(tweet)
             }
           }
         }
     
         Future.sequence(tweetsWithLatLonFutures)
       }
     
       private def randomLatLon: (Double, Double) = ((Random.nextDouble * 180) - 90, (Random.nextDouble * 360) - 180)
     
       private def lookupLatLon(query: String): Future[(Double, Double)] = {
         val locationFuture = WS.url("http://maps.googleapis.com/maps/api/geocode/json").withQueryString(
           "sensor" -> "false",
           "address" -> query
         ).get()
     
         locationFuture.map { response =>
           (response.json \\ "location").headOption.map { location =>
             ((location \ "lat").as[Double], (location \ "lng").as[Double])
           }.getOrElse(randomLatLon)
         }
       }
    
  8. In app/controllers/Application.scala update the fetchTweets function to use the new tweetLatLon function:

       def fetchTweets(query: String): Future[JsValue] = {
         val tweetsFuture = WS.url("http://search-twitter-proxy.herokuapp.com/search/tweets").withQueryString("q" -> query).get()
         tweetsFuture.flatMap { response =>
           tweetLatLon((response.json \ "statuses").as[Seq[JsValue]])
         } recover {
           case _ => Seq.empty[JsValue]
         } map { tweets =>
           Json.obj("statuses" -> tweets)
         }
       }
    
  9. Refresh your browser to see the TweetMap!

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