Web Development with Sinatra

What is Sinatra?

“Sinatra is a DSL for quickly creating web applications in
Ruby with minimal effort.” - sinatrarb.com/intro

It’s a LIBRARY not a FRAMEWORK.

http://stackoverﬂow.com/questions/148747/what-is-the-difference-between-a-framework-and-a-library

http://www.quora.com/Software-Engineering/Whats-the-difference-between-a-library-and-a-framework

“A library is essentially a set of functions that you
can call... Each call does some work and returns control to the client.” “A framework embodies some abstract design, with more behavior built in... you need to insert your behavior into various places in the framework.” http://martinfowler.com/bliki/InversionOfControl.html Martin Fowler

Sinatra allows you to structure your application to ﬁt the
problem you’re trying to solve instead of the other way around.

Simplest Example require 'sinatra' get '/hi' do "Hello World!" end
$ gem install sinatra $ ruby hi.rb == Sinatra has taken the stage .. >> Listening on 0.0.0.0:4567

Road Map • Fundamentals • “Advanced” Topics • Use Cases

Fundamentals Anatomy of a Route Handler HTTP Verb get post
put delete patch URL Behavior get '/hello/:name' do "Hello, #{params[:name]}" end Parameters

Fundamentals The First Sufﬁcient Match Wins get '/*' do "NOM
NOM NOM" end get '/specific' do "I'll never be matched... you'll won't see me!" end

Fundamentals Halting a Request get '/halt' do "You will not
see this output." halt 500 end

Fundamentals Redirecting a Request get '/search' do redirect 'http://www.google.com', 301
end Optional

Fundamentals Views: Inline Templates require 'sinatra' get '/index' do erb
:index end __END__ @@index <!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Inline Template</title> </head <body> <h1>It Worked!</h1> </body> </html> ERB by default, but any templates supported by Tilt will work Each inline template must have a unique name

Fundamentals Views: External Templates Just place your templates in a
/views folder and Sinatra will pick them up; you’re route handlers stay the same

Fundamentals Views: Passing Data get '/home' do @name = 'John
Doe' erb :home end __END__ @@home <!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Inline Template</title> </head <body> <h1><%= @name %></h1> </body> </html>

Fundamentals Filters before do content_type :json end after do "After
filter called" end

Fundamentals Helpers helpers do def link(name) case :name when :about
then '/about' when :index then '/index' else "/page/#{name}" end end # in your view template <a href="<%= link :about %>">About</a> # -- OR -- # define helpers as methods in a module module MyHelpers # helper methods end helpers MyHelpers

Fundamentals Conﬁguration configure :development do set :db, Sequel.sqlite('db/development.sqlite') end configure
:production do set :db, Sequel.connect(ENV['DATABASE_URL']) end

Fundamentals Caching get '/cache' do expires 3600, :public, :must_revalidate "This
page rendered at #{Time.now}." end See http://www.mnot.net/cache_docs/ for an explanation of HTTP caching options

Fundamentals Sessions configure do enable :sessions end get '/set' do
session[:foo] = Time.now "Session time was set." end get '/fetch' do "Session value: #{session[:foo]}" end get '/unset' do session.clear redirect '/fetch' end

Fundamentals Attachments before do content_type :txt end get '/attachment' do
attachment 'path/to/my-attachment.txt' end

Fundamentals Testing with rack-test require 'my_sinatra_app' require 'test/unit' require 'rack/test'
class MyAppTest < Test::Unit::TestCase include Rack::Test::Methods def app Sinatra::Application end def test_my_default get '/' assert_equal 'Hello World!', last_response.body end def test_with_params get '/meet', :name => 'Frank' assert_equal 'Hello Frank!', last_response.body end def test_with_rack_env get '/', {}, 'HTTP_USER_AGENT' => 'Songbird' assert_equal "You're using Songbird!", last_response.body end end

Advanced Topics Modular vs. “Classic” “For some reason, it is
a common misconception that modular applications are superior to classic applications, and that really advanced users only use modular style... This is utter nonsense and no one on the Sinatra core team shares this view. Sinatra is all about simplicity and if you can use a classic application, you should.” -- Sinatra Up and Running

Advanced Topics Reasons to Use Modular you don’t want to
pollute the Object namespace (writing a Gem) combining multiple Sinatra apps in a single process use Sinatra app as middleware

Advanced Topics Simplest Modular Example require 'sinatra/base' class MyApp <
Sinatra::Base get '/hi' do "Hello World!" end # Only start the server if the file # has been executed directly # # $0 is the executed file # __FILE__ is the current file run! if __FILE__ == $0 end

Advanced Topics Running with Rack: Rackup File # In a
file named my_app.rb require 'sinatra/base' class MyApp < Sinatra::Base get '/hi' do "Hello World!" end end # in a separate file named config.ru require './my_app' run MyApp # launch the server using # rackup command or shotgun

Advanced Topics Running with Rack: Middleware Chain # In a
file named my_app.rb require 'sinatra/base' class Foo < Sinatra::Base get('/foo') { 'foo' } end class Bar < Sinatra::Base get('/bar') { 'bar' } use Foo end # config.ru require 'my_app' run Bar # Or Foo and Bar can be in separate files # remember... it's just Ruby!

Advanced Topics Running with Rack: Cascade require 'sinatra/base' class Foo
< Sinatra::Base get('/foo') { 'foo' } end class Bar < Sinatra::Base get('/bar') { 'bar' } end # config.ru require 'my_app' run Rack::Cascade, [Foo, Bar] # Differences: # * _slightly_ better performance, but only if you have a lot of endpoints # * you can use any Rack app (like Rails)

Advanced Topics Extensions: LinkedIn Example

Use Cases Prototyping Web Apps API Server for iOS /
Android / JavaScript Apps HTML5 Mobile Apps

Resources • http://rubydoc.info/gems/sinatra/file/README.rdoc • http://www.sinatrarb.com/documentation • Sinatra: Up and Running
(http://shop.oreilly.com/product/0636920019664.do) • http://stackoverflow.com/questions/148747/what-is-the-difference-between-a- framework-and-a-library • http://www.quora.com/Software-Engineering/Whats-the-difference-between-a- library-and-a-framework • http://martinfowler.com/bliki/InversionOfControl.html • http://www.mnot.net/cache_docs/ • https://github.com/bnadlerjr/sidestep • https://github.com/bnadlerjr/leaflet • https://github.com/bnadlerjr/sinatra-linkedin • https://github.com/bnadlerjr/fuelyo • http://rubygems.org/gems/middleman

Questions? Bob Nadler @bnadlerjr [email protected]

Web Development with Sinatra

Web Development with Sinatra

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