Simple Twitter: Play Framework, AJAX, CRUD on Heroku

So the big announcement is out – Heroku started offering native support to Play Framework applications! If you haven’t heard it, checkout the post from Jesper Joergensen on Heroku’s blog.

So for the presentation, I am setting up a very basic Twitter clone; it’s meant to be simple yet it displays just enough of the productivity that Play! provides. I am gonna go through the steps to setup the demo application which should cover what was announced on Heroku’s blog post but with a little more depth.

First step let’s create the application

play new twitter

Add dependency to CRUD module (conf/dependencies.yml)

- play -> crud

Get the dependencies

play dependencies

IDE Integration

(for Eclipse)

play eclipsify

(for IntelliJ)

play idealize

(for Netbeans)

play netbeansify

Create Model (app/models/Tweet.java)

package models;

import java.util.Date;
import java.util.List;

import javax.persistence.Entity;

import play.data.validation.MaxSize;
import play.data.validation.Required;
import play.db.jpa.Model;

@Entity
public class Tweet extends Model {

	@Required
	@MaxSize(140)
	public String tweet;

	@Required
	public Date createDate = new Date();

	public static List findLatest() {
		return Tweet.find(“order by createDate desc”).fetch();
	}

	@Override
	public String toString() {
		return this.tweet;
	}

}

Define DB for JPA Models (conf/application.conf)

db=${DATABASE_URL}

Add Controller Actions (app/controllers/Application.java)

package controllers;

import java.util.List;

import models.Tweet;
import play.mvc.Controller;

public class Application extends Controller {

	public static void index() {
		List tweets = Tweet.findLatest();
		render(tweets);
	}

	public static void create(String msg) {
		Tweet tweet = new Tweet();
		tweet.tweet = msg;
		tweet.save();
		render(tweet);
	}

	public static void tweets() {
		List tweets = Tweet.findLatest();
		renderJSON(tweets);
	}
}

Define Main View (app/views/Application/index.html)

#{extends ‘main.html’ /}
#{set title:’Home’ /}

<!– Create Tweet Form –>

<form> <input name=”tweet” type=”text” />
<input type=”submit” value=”Tweet” /> </form><!– Latest Tweets List –>
<ul> #{list tweets}
<li>${_.tweet} (${_.createDate.since()})</li><p><p>
#{/list}</ul>
<!– JS –>
<script type=”text/javascript”>

	// Capture Form Submit Event
	$(‘form’).submit(function() {
	// Define Create Action
	var createAction = #{jsAction @create(‘:tweet’) /}

	// Call Create Action
	$.post(createAction({tweet: $(‘input:first’).val()}), function(data) {
	// Prepend Results to the List
	$(‘ul’).prepend(data);
	$(‘input:first’).val(”);

	});

	// Don’t let the browser redirect
	return false;
	});

</script>

Define Create Action View (app/views/Application/create.html)

<li><code>${tweet.tweet} (${tweet.createDate.since()})</li>

Create Unit Test for Tweet Model

import models.Tweet;

import org.junit.Assert;
import org.junit.Test;

import play.test.UnitTest;

public class TweetTest extends UnitTest {

	@Test
	public void testModelSave() {
		long count = Tweet.count();
		Tweet t = new Tweet();
		t.tweet = “my sample tweet”;
		t.save();
		long count2 = Tweet.count();
		Assert.assertEquals(count + 1, count2);
	}

}

Create CRUD Admin for Tweet Model

package controllers;
     public class Tweets extends CRUD {
}

Add Routes (conf/routes)

* /admin module:crud

GET /rest/tweets Application.tweets

Define Messages for CRUD Admin (conf/messages)

tweet=Tweet
createDate=Date Created

Define Profile

web: play run –%$FRAMEWORK_ID –http.port=$PORT -DusePrecompiled=$USE_PRECOMPILED -DDATABASE_URL=mem

Run in Development

play run –%dev -DusePrecompiled=false -DDATABASE_URL=mem

Create Application on Heroku

heroku create play-twitter –stack cedar

heroku create play-twitter –stack cedar

Setup Git Repository

git init; git add .; git commit -a -m “Initial Commit”; git remote add heroku git@heroku.com:play-twitter.git

Setup Heroku Environment Variables

heroku config:add FRAMEWORK_ID=prod; heroku config:add USE_PRECOMPILED=true

Deploy to Heroku

git push heroku master

If anything went wrong you can always check the log

heroku logs

To Setup a Real Database on Heroku

heroku addons:add shared-database

You can checkout a live demo here, the admin interface here or clone the source code on Github.

Reference: Step-by-Step for a Simple Twitter with Play Framework, AJAX, CRUD and Heroku from our JCG partner Felipe Oliveira at Geek Are Totally In.

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