Sinatra Basics

Sinatra Up and RunningTarcisio Coutinho

04-10-2013

About Me

● Bachelor in Computer Science at CIn - UFPE● Software Developer● 空手の学生 ● git & Github lover

@tacsio

What is Sinatra?

What is Sinatra?

Isn’t Francis Albert "Frank" Sinatra

Even if He has been a great singer… Now I’m listening him

What is Sinatra?

Sinatra is a domain-specific language for building websites, web services, and web applications in Ruby.

What is Sinatra?

It emphasizes a minimalistic approach to development, offering only what is essential to handle HTTP requests and deliver responses to clients.

Sinatra’s Characteristics

● Sinatra is not a framework○ Doesn’t have an ORM○ Predefined configuration files○ Neither defined structures of directories

● Flexible by nature

Do What You Want, Cause A Pirate Is Free...You Are A Pirate


● Good option for design APIs

● Simple ecosystem○ DSL○ HTTP Verbs○ Rack Middleware○ Sinatra Base


● Simple ecosystem○ DSL

■ Domain Specific Language○ HTTP Verbs○ Rack Middleware○ Sinatra Base


● Simple ecosystem○ DSL○ HTTP Verbs

■ Get Post Put Delete Options○ Rack Middleware○ Sinatra Base


● Simple ecosystem○ DSL○ HTTP Verbs○ Rack Middleware

■ Provides an minimal interface between

webservers supporting Ruby and Ruby frameworks.

○ Sinatra Base


● Simple ecosystem○ DSL○ HTTP Verbs○ Rack Middleware○ Sinatra Base

■ Sinatra application


● Templating (erb, haml)● Tests/specs (test:unit, rspec)● Filters (Before/After)● Helpers● Error Handlers● Inline templates● Code reloading (shotgun gem)● HTTP Caching (Etag)● Streams● Rack Middleware

Who is Using It?

● Github● Heroku● BBC● thoughtbot● Songbird● Engine Yard

Let’s start

Sinatra Installation

gem install sinatra

Hello Sinatra

require ‘sinatra’

get ‘/’ do“Hello, Sinatra!”

end

Routing

The First Sufficient Match Wins When Sinatra parses routes, the first sufficient match is the one that will be executed.

This is true even when there is a better or more specific route definition later in the file.

HTTP Verbs and REST

GET - Is used to ask a server to return a representation of a resourcePOST - Is used to submit data to a web server.PUT - Is used to create or update a representation of a resource on a server. DELETE - Is used to destroy a resource on a server.

Not Found (404) & Server Error (500)

not_found do“Route not found!”

end

error do“Server error!”

end

Route Params & Redirects

get ‘/posts/:id’ do@post = Post.find(params[:id])erb :post

end

post ‘/posts’ dopost = Post.create! paramsredirect “/posts/#{post.id}”

end

Static Files

Simple way to delivery static files

Directory Tree|-- public| `-- public.html|-- app.rb

public.htmlHello Sinatra!

app.rbrequire ‘sinatra’

Static Files :: If we got this scenario?

Directory Tree|-- public| `-- public.html|-- static_file.rb


get ‘/public.html’ do“This is delivery via the route.”

end

Views & Templates

Views in Sinatra are HTML templates that can optionally contain data passed from the application.

Available engines● Erb● Haml● Erubis● ...

Template mode● Inline Templates● External Templates

Inline Templates

Are defined in the application code file itself


get ‘/index’ doerb :index_inner

end

__END__@@index_inner

__END__@@index_inner

<!DOCTYPE html><html>

<body><h1>Hello Sinatra</h1></body>

</html>

External Templates

Sinatra will look for them by default in the views subfolder.

app.erbrequire ‘sinatra’

get ‘/index’ do@msg = “Hello Sinatra”erb :index

end

Views directory :: index.erb<!DOCTYPE html><html>

<body><h1><%= @msg %></h1></body>

</html>

Hands On

And now ?

Deploy on Heroku

We must configure the database properties

Development environmentconfigure :development do

set :database, ‘sqlite3:///db/database.sqlite’end

Production environmentconfigure :development do

ActiveRecord::Base.establish_connection(ENV['DATABASE_URL'] || 'postgres://localhost/mydb')end

Questions ?

References

1. Sinatra: Up and Running - O'Reilly Media2. http://www.sinatrarb.com3. https://github.com/sinatra/sinatra

http://www.sinatrarb.com/

http://www.sinatrarb.com/

https://github.com/sinatra/sinatra

https://github.com/sinatra/sinatra

Sinatra Basics

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