Sinatra

Sinatra is 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

Run with ruby myapp.rb and view at http://localhost:4567

HTTP Methods

  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 also triggered when a _method parameter is set to PUT or DELETE and the HTTP request method is POST

Routes

Routes are matched based on the order of declaration. The first route that matches the request is invoked.

Simple:

  get '/hi' do
    ...
  end

Named parameters:

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

Splat parameters:

  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

User agent matching:

  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 ends. Otherwise, Sinatra will look for an event that matches the path.

Views

Views are searched for in a "views" directory in the same location as your main application.

Haml Templates

  get '/' do
    haml :index
  end

Renders ./views/index.haml.

Erb

  get '/' do
    erb :index
  end

Renders ./views/index.erb

Builder

See Sinatra::Builder

Sass

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

Renders ./views/stylesheet.sass.

Inline Templates

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

Renders the inlined template string.

Accessing Variables

Templates are evaluated within the Sinatra::EventContext instance used to evaluate event blocks. Instance variables set in event blocks can be accessed direcly in views:

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

Or, specify an explicit Hash of local variables:

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

This is typically used when rendering templates as partials from within other templates.

In-file Templates

Templates may be defined at the end of the source file:

  get '/' do
    haml :index
  end

  use_in_file_templates!

  __END__

  @@ layout
  X
  = yield
  X

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

It’s also possible to define named templates using the top-level template method:

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

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

  get '/' do
    haml :index
  end

Helpers

The top-level helpers method takes a block and extends all EventContext instances with the methods defined:

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

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

Filters

These are run in Sinatra::EventContext before every event.

  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

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 and Reloading

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

Because Sinatra gives 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'

Rack Middleware

Sinatra rides on Rack[http://rack.rubyforge.org/], 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[http://rack.rubyforge.org/doc/classes/Rack/Builder.html] 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

Specs

  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

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)

Contributing

Tools

Besides Ruby itself, you only need a text editor, preferably one that supports Ruby syntax hilighting. VIM and Emacs are a fine choice on any platform, but feel free to use whatever you’re familiar with.

Sinatra uses the Git source code management system. If you’re unfamiliar with Git, you can find more information and tutorials on http://git.or.cz/ as well as http://git-scm.com/. Scott Chacon created a great series of introductory screencasts about Git, which you can find here: http://www.gitcasts.com/

First Time: Cloning The Sinatra Repo

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

Updating Your Existing Sinatra Clone

  cd where/you/keep/sinatra
  git pull

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
  end

Contributing a Patch

There are several ways to do this. Probably the easiest (and preferred) way is to fork Sinatra on GitHub (http://github.com/bmizerany/sinatra), push your changes to your Sinatra repo, and then send Blake Mizerany (bmizerany on GitHub) a pull request.

You can also create a patch file and attach it to a feature request or bug fix on the issue tracker (see below) or send it to the mailing list (see Community section).

Issue Tracking and Feature Requests

http://sinatra.lighthouseapp.com/

Community

Mailing List

http://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 we cannot pay attention to the channel all the time, so please stick around for a while after asking a question.