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<!doctype html>
<html>
<head>
<title>Programming for the Web with Ruby</title>
<meta charset="utf-8">
<meta name="author" content="Satish Talim" >
<meta name="keywords" content="programming, Ruby, Rack, Sinatra" >
<meta name="description" content="A Ruby programming tutorial on topics that hopefully will help those that have some knowledge of Ruby programming to get started with web programming." >
<link rel="stylesheet" href="stylesheets/intruby.css">
</head>
<body>
<div>
<p>
<strong>
<a href="chapter8.html"><Chapter 8 | </a>
<a href="toc.html">TOC | </a>
<a href="chapter9.html">Chapter 9></a>
</strong>
</p>
<h1 class="title">Day 10</h1>
<h2>Sinatra with MongoDB</h2>
<p>Some concepts that are core to web development (and which we have covered earlier - the HTTP specification, HTML, CSS, etc.) are critical to understanding how to be productive with Sinatra; I recommend that you have at least a passing familiarity with these concepts to make the Sinatra experience a little easier.</p>
<h3>What's Sinatra?</h3>
<p><a href="http://www.sinatrarb.com/">Sinatra</a> is a Ruby-based web application library. Sinatra is not a <a href="http://en.wikipedia.org/wiki/Web_application_framework">web application framework</a> and unlike Rails, there's no enforcement of concepts like <a href="http://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller">MVC</a> or <a href="http://en.wikipedia.org/wiki/Representational_state_transfer">REST</a> in Sinatra.</p>
<p>It doesn't assume much about your application, apart from that:</p>
<ul>
<li>it will be written in the Ruby programming language</li>
<li>it will have URLs</li>
</ul>
<p>Sinatra serves as a lightweight wrapper around Rack middleware, with syntax that maps closely to functions exposed by HTTP verbs.</p>
<p>Sinatra is used to build websites, web services and web applications in Ruby.</p>
<h3>Create a folder on your hard disk</h3>
<p>Create a folder <code>sinatraapp</code>. This is where we will store our Sinatra app.</p>
<h3>Install Sinatra</h3>
<p>The simplest way to obtain Sinatra is through Rubygems.</p>
<p>In the folder <code>sinatraapp</code>, open a command window and type:</p>
<pre>$ gem install sinatra
</pre>
<h3>Which web server?</h3>
<p>The <code>Thin</code> web server is recommended. <code>Thin</code> uses code from <code>Mongrel</code> web server to parse HTTP requests but improves network I/O performance via EventMachine, which manages evented network communication. To install <code>Thin</code>, in the already open command window, type:</p>
<pre>$ gem install thin
</pre>
<p>If <code>Thin</code> is not installed, Sinatra will first try to run with <code>Mongrel</code>, choosing <code>WEBrick</code> if <code>Mongrel</code> isn't available either.</p>
<h3>Our trivial Sinatra application</h3>
<p>In the folder <code>sinatraapp</code> write a program, call it <code>myapp1.rb</code>, as follows:</p>
<pre>require 'sinatra'
get '/' do
"Hello Ruby participants from across the globe!"
end
</pre>
<p>In the open command window, type:</p>
<pre>$ ruby myapp1.rb
[2011-11-25 10:15:18] INFO WEBrick 1.3.1
[2011-11-25 10:15:18] INFO ruby 1.9.3 (2011-10-30) [i386-mingw32]
== Sinatra/1.3.1 has taken the stage on 4567 for development with backup from WEBrick
[2011-11-25 10:15:18] INFO WEBrick::HTTPServer#start: pid=7644 port=4567
</pre>
<p>As you can see above, you will be notified that Sinatra has taken the stage.</p>
<p>Sinatra uses port 4567 by default. Open a web browser and navigate to <a href="http://localhost:4567/">http://localhost:4567/</a>. Your Sinatra application should respond with our greeting namely:</p>
<pre>Hello Ruby participants from across the globe!
</pre>
<p>Let's look at what the following does:</p>
<pre>get '/' do
</pre>
<p>To declare a route in Sinatra, you must supply the HTTP verb to respond to, the specific URL, and then optionally define the behavior desired for the route.</p>
<p>The form <code>verb 'route' do</code> in our code instructs the application to respond to HTTP GET requests to the path '/'; our response is composed by the block we provided for behavior. This composite endpoint is referred to as a <em>route</em>.</p>
<p>Now let's use <code>cURL</code> to see what happens when this route is executed. Open a new command window, type:</p>
<pre>$ curl http://localhost:4567
Hello Ruby participants from across the globe!
</pre>
<p>Let us use the <code>-v</code> switch with <code>cURL</code>, type:</p>
<pre>$ curl -v http://localhost:4567
* About to connect() to localhost port 4567 (#0)
* Trying 127.0.0.1... connected
> GET / HTTP/1.1
> User-Agent: curl/7.22.0 (i386-pc-win32) libcurl/7.22.0 OpenSSL/0.9.8r zlib/1.2.5
> Host: localhost:4567
> Accept: */*
>
< HTTP/1.1 200 OK
< X-Frame-Options: sameorigin
< X-Xss-Protection: 1; mode=block
< Content-Type: text/html;charset=utf-8
< Content-Length: 26
< Server: WEBrick/1.3.1 (Ruby/1.9.3/2011-10-30)
< Date: Fri, 25 Nov 2011 08:51:01 GMT
< Connection: Keep-Alive
<
Hello Ruby participants from across the globe!* Connection #0 to host localhost left intact
* Closing connection #0
</pre>
<p>Close this command window.</p>
<p><b>Note</b>: The switch <code>-v</code> or <code>--verbose</code> makes the fetching more verbose/talkative. Mostly useful for debugging. A line starting with '>' means "header data" sent by <code>cURL</code>, '<' means "header data" received by <code>cURL</code> that is hidden in normal cases, and a line starting with '*' means additional info provided by <code>cURL</code>.</p>
<p>Remember that routes in your application are matched in top-down order; the first route that matches the incoming request is the one that gets used. Routes in Sinatra can also accept parameters that are exposed in code via the <code>params</code> array. Example:</p>
<pre>require 'sinatra'
post '/login' do
username = params[:username]
password = params[:password]
end
</pre>
<p>In the open command window, press Ctrl C to stop Sinatra. Close the command window.</p>
<h3>ERB and View</h3>
<h4>ERB</h4>
<p>ERB is written in pure Ruby and is included with the standard Sinatra distribution. ERB allows you to embed Ruby statements in an HTML page.</p>
<p>The important thing to know about an <code>.erb</code> file is that <code><%= ruby_code %></code> evaluates the ruby code and outputs the result, and <code><% ruby_code %></code> evaluates the code, but doesn't output anything.</p>
<h4>View</h4>
<p><em>A view is responsible for generating a user interface, normally based on data</em>. For example, an online store will have a list of products to be displayed on a catalogue screen. The view accesses the data and formats it for the end user.</p>
<p><em>All file-based views are looked up in</em>:</p>
<pre>root
| - views/
</pre>
<p><em>Sinatra has built-in support for ERB, Haml, Sass and Builder (we do not use the latter three here) templating languages</em>. Let's use ERB for our example. In the folder <code>sinatraapp</code> write a program, call it <code>myapp2.rb</code>, as follows:</p></p>
<pre>require 'sinatra'
get '/' do
erb :index
end
</pre>
<p><em>This tells Sinatra that when a GET request for '/' comes in, that we should use the ERB helper to render the <code>index.erb</code> template, which is stored in the <code>views/</code> subdirectory by convention and marked up with embedded Ruby (ERB).</em></p>
<p>Create a <code>views</code> sub folder under the existing <code>sinatraapp</code> folder and create the file <code>index.erb</code> in it, which contains the following:</p>
<pre><h1>Introduction to Sinatra Course by RubyLearning</h1>
<p>The first and only free Sinatra course on the planet!!</p>
<p>The current time is: <%= Time.now %></p>
</pre>
<p>Open a new command window and type:</p>
<pre>$ ruby myapp2.rb
[2011-12-22 15:04:10] INFO WEBrick 1.3.1
[2011-12-22 15:04:10] INFO ruby 1.9.3 (2011-10-30) [i386-mingw32]
== Sinatra/1.3.1 has taken the stage on 4567 for development with backup from WEBrick
[2011-12-22 15:04:10] INFO WEBrick::HTTPServer#start: pid=4404 port=4567
</pre>
<p>Open a web browser and navigate to <a href="http://localhost:4567/">http://localhost:4567/</a>. Your Sinatra application should respond with:</p>
<pre>Introduction to Sinatra Course by RubyLearning
The first and only free Sinatra course on the planet!!
The current time is: 2011-12-22 15:05:48 +0530
</pre>
<p>In the open command window, press Ctrl C to stop Sinatra. Close the command window.</p>
<h4>Handlers and Form parameters</h4>
<p>Handler is the generic term that Sinatra uses for the "controllers". <em>A handler is the initial point of entry for new HTTP requests into your application</em>.</p>
<p>In handlers you can reach submitted form parameters directly via the <code>params</code> hash, namely:</p>
<pre>params[:post]
</pre>
<p>Also, the support of nested parameters is built-in Sinatra. For example:</p>
<pre><form>
<input ... name="post[title]" /><br />
<input ... name="post[body]" /><br />
<input ... name="post[author]" />
</form>
</p>
</pre>
<p>The parameters in this case become as a hash:</p>
<pre>{:post=>{ :title=>"", :body=>"", :author=>"" }}
</pre>
<p>Therefore in handlers you can use nested parameters like a regular hash:</p>
<pre>params[:post][:title]
</pre>
<p>An example will illustrate what we have learned so far about form parameters:</p>
<p>In the folder <code>sinatraapp</code> write a program, call it <code>myapp3.rb</code>, as follows:</p>
<pre># myapp3.rb
require 'sinatra'
get '/' do
erb :home
end
post '/display' do
erb :show
end
</pre>
<p>Create the files <code>home.erb</code> and <code>show.erb</code> in the <code>views</code> folder, as follows:</p>
<p><b>home.erb</b></p>
<pre><h1>Form Parameters</h1>
<p>The example will display submitted form parameters directly via the params hash</p>
<form action="/display" method="post" accept-charset="utf-8">
<input type="text" name="post[fname]" value="Type your first name..." id="fname" /><br />
<input type="text" name="post[lname]" value="Type your last name...." id="lname" /><br />
<input type="submit" value=".. and display it!">
</form>
</pre>
<p><b>show.erb</b></p>
<pre><h1>Form Parameters Display</h1>
<p>You had entered:</p>
<p>First Name - <%= params[:post][:fname] %></p>
<p>Last Name - <%= params[:post][:lname] %></p>
<p>Click <a href="/">here</a> to try a new name.</p>
</pre>
<p>Open a new command window and type:</p>
<pre>$ ruby myapp3.rb
[2011-12-23 08:28:25] INFO WEBrick 1.3.1
[2011-12-23 08:28:25] INFO ruby 1.9.3 (2011-10-30) [i386-mingw32]
== Sinatra/1.3.1 has taken the stage on 4567 for development with backup from WEBrick
[2011-12-23 08:28:25] INFO WEBrick::HTTPServer#start: pid=7924 port=4567
</pre>
<p>Open a web browser and navigate to <a href="http://localhost:4567/">http://localhost:4567/</a>. Your Sinatra application should respond with:</p>
</div>
<div style="width:image 560 px; font-size:80%; text-align:center;"><img src="images/form.jpg" alt="Form" style="padding-bottom:0.5em;" /><br />Sinatra Form</div>
<div>
<p>In the open command window, press Ctrl C to stop Sinatra. Close the command window.</p>
<h2>Exercise: A simple text reversing service</h2>
<p>Build a simple text reversing Sinatra app that accepts a text string from the user and displays to the user the text string reversed. Store your code in a GitHub repo and post your repo URL in the technical forum.</p>
<h2>Deploy a Sinatra app to Heroku</h2>
<p>In order for Heroku to know what to do with your Sinatra app, create a <code>config.ru</code> in the root-directory i.e. folder <code>sinatraapp</code>. The contents are:</p>
<pre>require './myapp3'
run Sinatra::Application
</pre>
<p>The key line is <code>require 'myapp3'</code> (we are going to use the program <code>myapp3.rb</code> written above). Be sure to change that to whatever your application's name is. This line helps to load rubygems, Sinatra, rack and everything that we need. Heroku sets <code>RACK_ENV</code> to production for you. Finally we tell rack to run our Sinatra application with the line <code>run Sinatra::Application</code>. This will run "myapp3" in our case.</p>
<p>Next, we will install the required gems via bundler. Open a Bash shell for folder <code>sinatraapp</code> and type:</p>
<pre>$ bundle init
Writing new Gemfile to c:/sinatraapp/Gemfile
</pre>
<p>Edit the created Gemfile with your preferred text editor to let it look like this:</p>
<pre>source "http://rubygems.org"
gem 'sinatra'
</pre>
<p>Now we need to tell Bundler to check if we're missing the gems our application depends on, if so, tell it to install them. In your open Bash shell type:</p>
<pre>$ bundle check
The following gems are missing ...
</pre>
<p>Finally in the open Bash shell, type:</p>
<pre>$ bundle install
</pre>
<p>This will ensure all gems specified on Gemfile, together with their dependencies, are available for your application. Running "bundle install" will also generate a "Gemfile.lock" file. The Gemfile.lock ensures that your deployed versions of gems on Heroku match the version installed locally on your development machine.</p>
<p>Set up your local app to use Git. I have the <code>myapp3.rb</code> and <code>config.ru</code> files already in <code>sinatraapp</code>. Open a command window in folder <code>sinatraapp</code> and type the following:</p>
<pre>$ git init
$ git add .
$ git commit -m "myapp3 first commit"
</pre>
<p><b>Note</b>: The location of the <code>config.ru</code> file is in the folder <code>sinatraapp</code>.</p>
<p>Next we create the app on heroku. In the already open Bash shell, type:</p>
<pre>$ heroku create
Creating afternoon-winter-7405... done, stack is bamboo-mri-1.9.2
http://afternoon-winter-7405.heroku.com/ | git@heroku.com:afternoon-winter-7405.
git
</pre>
<p>The final line of output from the create command <em>will be different for each one of you</em> and is something like this:</p>
<pre>http://afternoon-winter-7405.heroku.com/ | git@heroku.com:afternoon-winter-7405.git
</pre>
<p>The app has been created and two URLs are provided. One is for the web face of your new app i.e. <a href="http://afternoon-winter-7405.heroku.com/">http://afternoon-winter-7405.heroku.com/</a>. The other one is for the Git repository that you will push your code to. Normally you would need to add this as a git remote; the "heroku create" command has done this for you automatically.</p>
<p>Let us now deploy our code:</p>
<pre>$ git push heroku master
</pre>
<p><b>Note</b>: At this stage you can rename your app by:</p>
<pre>$ heroku rename app_newname
</pre>
<p>Congrats, you have successfully deployed your first Sinatra app. For other deployment options, refer the URL - <a href="http://sinatra-book.gittr.com/#deployment">http://sinatra-book.gittr.com/#deployment</a>.</p>
<h2>Exercise: Deploy the simple text reversing service app to Heroku</h2>
<p>Deploy to Heroku the simple text reversing Sinatra app that you just built. Post the URL in the technical forum.</p>
<h2>Sinatra and Rack Middleware</h2>
<p>Sinatra rides on Rack, a minimal standard interface for Ruby web frameworks. As seen earlier, one of Rack's most interesting capabilities for application developers is support for "middleware" - components that sit between the server and your application monitoring and/or manipulating the HTTP request/response to provide various types of common functionality.</p>
<p>Sinatra makes building Rack middleware easier by using the top-level <code>use</code> method. Let's use our middleware program namely <code>my_middleware.rb</code> which is in the folder <code>my_ruby_programs</code>. In this folder write a program, call it <code>my_sinatra.rb</code>, as follows:
<pre>require 'sinatra'
require './my_middleware'
use MyMiddleware::Hello
get '/' do
"Hello Ruby participants from across the globe!"
end
</pre>
<p>Open a command window and type:</p>
<pre>$ ruby my_sinatra.rb
[2012-02-12 08:22:09] INFO WEBrick 1.3.1
[2012-02-12 08:22:09] INFO ruby 1.9.3 (2011-10-30) [i386-mingw32]
== Sinatra/1.3.1 has taken the stage on 4567 for development with backup from WEBrick
[2012-02-12 08:22:09] INFO WEBrick::HTTPServer#start: pid=4288 port=4567
</pre>
<p>Open a web browser and navigate to <a href="http://localhost:4567/">http://localhost:4567/hello</a>. Your Sinatra application should respond with our greeting namely:</p>
<pre>Hello from the middleware!
</pre>
<p>In the open command window, press Ctrl C to stop Sinatra. Close the command window.</p>
<h2>Sinatra and Rack HTTP Basic Authentication</h2>
<p>You can easily protect your Sinatra application using HTTP Basic Authentication with the help of Rack middlewares. In the folder <code>my_ruby_programs</code> type the program <code>my_sinatra2.rb</code:</p>
<pre>require 'sinatra'
use Rack::Auth::Basic, "Restricted Area" do |user, password|
user == 'super' && password == 'secretsauce'
end
get '/' do
"This is a secret page"
end
get '/files' do
"Here are the secret files"
end
</pre>
<p>Open a command window and type:</p>
<pre>$ ruby my_sinatra2.rb
[2012-02-12 08:22:09] INFO WEBrick 1.3.1
[2012-02-12 08:22:09] INFO ruby 1.9.3 (2011-10-30) [i386-mingw32]
== Sinatra/1.3.1 has taken the stage on 4567 for development with backup from WEBrick
[2012-02-12 08:22:09] INFO WEBrick::HTTPServer#start: pid=4288 port=4567
</pre>
<p>Open a web browser and navigate to <a href="http://localhost:4567">http://localhost:4567</a>. Your Sinatra application should respond by asking you for the User Name and Password. Enter "super" and "secretsauce" respectively and the browser page would display:</p>
<pre>This is a secret page
</pre>
<p>If you type the url: <a href="http://localhost:9292/files">http://localhost:9292/files</a> in your browser window you should see something like this:</p>
<pre>Here are the secret files
</pre>
<p>In the open command window, press Ctrl C to stop Sinatra. Close the command window.</p>
<h2>Introduction to Sinatra eBook (Updated 15th Sept. 2011)</h2>
<p>We have had a very quick look at Sinatra. For a more detailed look, you could consider buying the <a href="http://rubylearning.com/blog/introduction-to-sinatra-ebook/">Introduction to Sinatra eBook</a>, an easy-to-follow guide to everything on Sinatra.</p>
<p>It is priced at a reasonable <b>US$ 14.95</b>. The money collected helps me maintain the site and provide quality content to you all.</p>
<p>Purchase of this eBook is <b>not mandatory</b> for this course.</p>
<p>WIP...</p>
<!--
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http://ruby.bastardsbook.com/chapters/html-parsing/
http://ruby.bastardsbook.com/chapters/methods-and-gems/
-->
<h2>References</h2>
<ul>
<li><a href="http://rubylearning.com/blog/using-git-github-ebook/">http://rubylearning.com/blog/using-git-github-ebook/</a></li>
<li><a href="http://progit.org/book/">Pro Git</a></li>
<li><a href="http://learningwebdesign.com/">http://learningwebdesign.com/</a></li>
<li><a href="http://www.html-5-tutorial.com/">http://www.html-5-tutorial.com/</a></li>
<li><a href="http://www.w3schools.com/html/html_primary.asp">http://www.w3schools.com/html/html_primary.asp</a></li>
<li><a href="http://www.cssbasics.com/">http://www.cssbasics.com/</a></li>
<li><a href="http://www.w3schools.com/js/">http://www.w3schools.com/js/</a></li>
<li><a href="http://ruby.bastardsbook.com/chapters/html-parsing/">Parsing HTML with Nokogiri</a></li>
<li><a href="http://blog.segment7.net/2010/11/15/how-to-name-gems">http://blog.segment7.net/2010/11/15/how-to-name-gems</a></li>
<li><a href="http://rubylearning.com/blog/2010/10/06/gem-sawyer-modern-day-ruby-warrior/">http://rubylearning.com/blog/2010/10/06/gem-sawyer-modern-day-ruby-warrior/</a></li>
<li><a href="http://guides.rubygems.org/make-your-own-gem/">http://guides.rubygems.org/make-your-own-gem/</a></li>
<li><a href="http://coderack.org/">http://coderack.org/</a></li>
<li><a href="http://m.onkey.org/ruby-on-rack-2-the-builder">http://m.onkey.org/ruby-on-rack-2-the-builder</a></li>
<li><a href="http://rubysource.com/php-vs-ruby-whats-the-point/">http://rubysource.com/php-vs-ruby-whats-the-point/</a></li>
<li><a href="http://rubysource.com/rack-for-middlewares/">http://rubysource.com/rack-for-middlewares/</a></li>
<li><a href="http://devcenter.heroku.com/articles/static-sites-on-heroku">http://devcenter.heroku.com/articles/static-sites-on-heroku</a></li>
<li><a href="http://www.w3schools.com/json/default.asp">http://www.w3schools.com/json/default.asp</a></li>
<li><a href="https://github.com/karlseguin/the-little-mongodb-book">https://github.com/karlseguin/the-little-mongodb-book</a></li>
<li><a href="http://rubylearning.com/blog/2010/12/21/being-awesome-with-the-mongodb-ruby-driver/">http://rubylearning.com/blog/2010/12/21/being-awesome-with-the-mongodb-ruby-driver/</a></li>
<li><a href="http://api.mongodb.org/ruby/current/file.TUTORIAL.html">http://api.mongodb.org/ruby/current/file.TUTORIAL.html</a></li>
<li><a href="http://shop.oreilly.com/product/0636920019664.do">http://shop.oreilly.com/product/0636920019664.do</a></li>
<li><a href="http://sinatra.rubylearning.org/">Sinatra and only Sinatra!</a></li>
</ul>
<p>
<strong>
<a href="chapter8.html"><Chapter 8 | </a>
<a href="toc.html">TOC | </a>
<a href="chapter9.html">Chapter 9></a>
</strong>
</p>
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