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Sinatra

Sinatra a DSL for quickly creating web-applications in Ruby with minimal effort.

Sample app:

# myapp.rb

require 'rubygems'
require 'sinatra'

get '/' do
  'Hello world!'
end

Ruby this as ruby myapp.rb and view at localhost:4567

RESTful

get '/' do
  .. show things ..
end

post '/' do
  .. create something ..
end

put '/' do
  .. update something ..
end

delete '/' do
  .. annihilate something ..
end

head '/' do

end

NOTE: put and delete are triggered when a _method param is set to PUT or DELETE and the HTTP_REQUEST_METHOD is a POST

Routes

NOTE: Routes are looked up in order of declaration

Simple

get '/hi' do
  ...
end

With params

get '/:name' do
  # matches /sinatra and the like and sets params[:name]
end

Splat'n

get '/say/*/to/*' do
  # matches /say/hello/to/world
  params["splat"] # => ["hello", "world"]
end

get '/download/*.*' do
  # matches /download/path/to/file.xml
  params["splat"] # => ["path/to/file", "xml"]
end

Get an agent!

get '/foo', :agent => /Songbird (\d\.\d)[\d\/]*?/ do
  "You're using Songbird version #{params[:agent][0]}"
end

get '/foo' do
  # matches non-songbird browsers
end

Static files

Put all of your static content in the ./public directory

root
  \ public

If a file exists that maps to the REQUEST_PATH then it is served and the request end; Sinatra will look for and event that matches the path otherwise

Views (if you need MVC)

All file-based views are looked up in:

root
  | - views/

Templates

Haml

get '/' do
  haml :index
end

This will render ./views/index.haml

Sass

get '/stylesheet.css' do
  content_type 'text/css', :charset => 'utf-8'
  sass :stylesheet
end

This will render ./views/stylesheet.sass

Inline

get '/' do
  haml '%div.title Hello World'
end

This will render the inlined template string

Accessing Variables

Templates are rendered in the context the current Sinatra::EventContext. This means you get all instance/class variables and methods it has access to.

get '/:id' do
  @foo = Foo.find(params[:id])
  haml '%h1== @foo.name'
end

Send local objects like:

get '/:id' do
  localvar = Foo.find(params[:id])
  haml '%h1== localvar.name', :locals => { :localvar => localvar }
end

This is more ideal for rendering templates as partials from within templates

In file templates

This one is cool:

get '/' do
  haml :index
end

use_in_file_templates!

__END__

@@ layout
X
= yield
X

@@ index
%div.title Hello world!!!!!

Try it!

You can do this too but it's not as cool

template :layout do
  "X\n=yield\nX"
end

template :index do
  '%div.title Hello World!'
end

get '/' do
  haml :index
end

Erb

This works like Haml except you use erb instead of haml

Sass

This works like Haml except you use sass instead of haml. It's also a good idea to add content_type 'text/css', :charset => 'utf-8' before your call to sass so Sinatra returns the proper content type header with the file.

Builder

See Sinatra::Builder

Helpers

It is ill-advised to create helpers on (main). Use the handy helpers to install helper methods on Sinatra::EventContext for use inside events and templates.

Example:

helpers do

  def bar(name)
    "#{name}bar"
  end

end

get '/:name' do
  bar(params[:name])
end

Before filters

These are run in Sinatra::EventContext

before do
  .. this code will run before each event ..
end

Halt!

To immediately stop a request during a before filter or event use:

throw :halt

Variations

Set the body to the result of a helper method

throw :halt, :helper_method

Set the body to the result of a helper method after sending it parameters from the local scope

throw :halt, [:helper_method, foo, bar]

Set the body to a simple string

throw :halt, 'this will be the body'

Set status then the body

throw :halt, [401, 'go away!']

Set the status then call a helper method with params from local scope

throw :halt, [401, [:helper_method, foo, bar]]

Run a proc inside the Sinatra::EventContext instance and set the body to the result

throw :halt, lambda { puts 'In a proc!'; 'I just wrote to $stdout!' }

Create you own to_result

class MyResultObject
  def to_result(event_context, *args)
    event_context.body = 'This will be the body!
  end
end

get '/' do
  throw :halt, MyResultObject.new
end

Get the gist? If you want more fun with this then checkout to_result on Array, Symbol, Fixnum, NilClass.

Configuration & Re-loading

Sinatra supports multiple environments and re-loading. Re-loading happens on every request when in :development. Wrap your configurations in configure (i.e. Database connections, Constants, etc.) to protect them from re-loading and to only work in certain environments.

All environments:

configure do

end

Production

configure :production do

end

Two at a time:

configure :production, :test do

end

This is also really nifty for error handling.

Error handling

Not Found

Remember: These are run inside the Sinatra::EventContext which means you get all the goodies is has to offer (i.e. haml, erb, :halt, etc.)

Whenever NotFound is raised this will be called

not_found do
  'This is nowhere to be found'
end

Error

By default error will catch Sinatra::ServerError

Sinatra will pass you the error via the 'sinatra.error' in request.env

error do
  'Sorry there was a nasty error - ' + request.env['sinatra.error'].name
end

Custom error mapping:

error MyCustomError do
  'So what happened was...' + request.env['sinatra.error'].message
end

then if this happens:

get '/' do
  raise MyCustomError, 'something bad'
end

you gets this:

So what happened was... something bad

one guess what this does ;)

not_found do
  'I have no clue what you're looking for'
end

Try it!

Because Sinatra give you a default not_found and error do :production that are secure. If you want to customize only for :production but want to keep the friendly helper screens for :development then do this:

configure :production do

  not_found do
    "We're so sorry, but we don't what this is"
  end

  error do
    "Something really nasty happened.  We're on it!"
  end

end

Mime types

When using send_file or static files you may have mime types Sinatra doesn't understand. Use mime in those cases.

mime :foo, 'text/foo'

Using Rack Middleware

Sinatra rides on Rack, a minimal standard interface for Ruby web frameworks. 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. What's more, middleware is portable between web frameworks, so middleware components developed under, e.g., Merb, can be used with Sinatra and vice versa.

Sinatra makes building Rack middleware pipelines a cinch via a top-level use method:

require 'sinatra'
require 'my_custom_middleware'

use Rack::Lint
use MyCustomMiddleware

get '/hello' do
  'Hello World'
end

The semantics of use are identical to those defined for the Rack::Builder DSL (most frequently used from rackup files). For example, the use method accepts multiple/variable args as well as blocks:

use Rack::Auth::Basic do |username, password|
  username == 'admin' && password == 'secret'
end

Rack is distributed with a variety of standard middleware for logging, debugging, URL routing, authentication, and session handling. Sinatra uses many of of these components automatically based on configuration so you typically don't have to use them explicitly.

Testing

Methods

get_it path, params
get_it path, params.merge(:env => { 'HTTP_HOST' => 'www.sinatrarb.com' }) or
get_it path, params.merge(:env => { :host => 'www.sinatrarb.com' })

RESTful:

post_it '/foo', '<myxml></myxml>', 'HTTP_ACCEPT' => 'application/xml'

also works with:

get_it, post_it, put_it, delete_it, head_it

Test/Unit

require 'my_sinatra_app'
require 'sinatra/test/unit'

class MyAppTest < Test::Unit::TestCase

  def test_my_default
    get_it '/'
    assert_equal 'My Default Page!', @response.body
  end

  def test_with_agent
    get_it '/', :agent => 'Songbird'
    assert_equal 'You're in Songbird!', @response.body
  end

  ...

end

Test/Spec

require 'my_sinatra_app'
require 'sinatra/test/spec'

context 'My app'

  should "show a default page" do
    get_it '/'
    should.be.ok
    body.should.equal 'My Default Page!'
  end
  ...

end

Test helpers

See Sinatra::Test::Methods

Irb

This will be back in soon

Command line

Run your sinatra file like:

ruby myapp.rb [options]

Options are:

-h # help
-p # set the port (default is 4567)
-e # set the environment (default is development)
-x # turn on the mutex lock (default is off)

Contribute

First Time: Cloning the sinatra repo

cd where/you/keep/your/projects
git clone git://github.com/bmizerany/sinatra.git
cd sinatra
git submodule update --init
cd path/to/your_project
ln -s ../sinatra/

Updating your existing Sinatra clone

cd where/you/keep/sinatra
git pull
git submodule update --init

Using edge Sinatra in your app

at the top of your sinatra_app.rb file:

$:.unshift File.dirname(__FILE__) + '/sinatra/lib'
require 'sinatra'

get '/about' do
  "I'm running on Version " + Sinatra::Version.combined
end

Community

Mailing List

groups.google.com/group/sinatrarb

If you have a problem or question, please make sure to include all the relevant information in your mail, like the Sinatra version you're using, what version of Ruby you have, and so on.

IRC Channel

You can find us on the Freenode network in the channel #sinatra (irc://chat.freenode.net/#sinatra)

There's usually someone online at any given time, but since we cannot pay attention to the channel all the time, so please stick around for a while after asking a question.

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