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 http://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[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

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

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

at the top of your sinatra.rb file

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

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