= Sinatra

Sinatra is a DSL for quickly creating web applications in Ruby with minimal
effort:

  # myapp.rb
  require 'rubygems'
  require 'sinatra'
  get '/' do
    'Hello world!'
  end

Install the gem and run with:

  sudo gem install sinatra
  ruby myapp.rb

View at: http://localhost:4567

== Routes

In Sinatra, a route is an HTTP method paired with an URL matching pattern.
Each route is associated with a block:

  get '/' do
    .. show something ..
  end

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

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

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

Routes are matched in the order they are defined. The first route that
matches the request is invoked.

Route patterns may include named parameters, accessible via the
<tt>params</tt> hash:

  get '/hello/:name' do
    # matches "GET /hello/foo" and "GET /hello/bar"
    # params[:name] is 'foo' or 'bar'
    "Hello #{params[:name]}!"
  end

You can also access named parameters via block parameters:

  get '/hello/:name' do |n|
    "Hello #{n}!"
  end

Route patterns may also include splat (or wildcard) parameters, accessible
via the <tt>params[:splat]</tt> array.

  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

Route matching with Regular Expressions:

  get %r{/hello/([\w]+)} do
    "Hello, #{params[:captures].first}!"
  end

Or with a block parameter:

  get %r{/hello/([\w]+)} do |c|
    "Hello, #{c}!"
  end

Routes may include a variety of matching conditions, such as the user 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

Static files are served from the <tt>./public</tt> directory. You can specify
a different location by setting the <tt>:public</tt> option:

  set :public, File.dirname(__FILE__) + '/static'

Note that the public directory name is not included in the URL. A file
<tt>./public/css/style.css</tt> is made available as
<tt>http://example.com/css/style.css</tt>.

== Views / Templates

Templates are assumed to be located directly under the <tt>./views</tt>
directory. To use a different views directory:

  set :views, File.dirname(__FILE__) + '/templates'

One important thing to remember is that you always have to reference
templates with symbols, even if they're in a subdirectory (in this
case use <tt>:'subdir/template'</tt>). Rendering methods will render
any strings passed to them directly.

=== Haml Templates

The haml gem/library is required to render HAML templates:

  ## You'll need to require haml in your app
  require 'haml'

  get '/' do
    haml :index
  end

Renders <tt>./views/index.haml</tt>.

{Haml's options}[http://haml.hamptoncatlin.com/docs/rdoc/classes/Haml.html]
can be set globally through Sinatra's configurations,
see {Options and Configurations}[http://www.sinatrarb.com/configuration.html],
and overridden on an individual basis.

  set :haml, {:format => :html5 } # default Haml format is :xhtml

  get '/' do
    haml :index, :haml_options => {:format => :html4 } # overridden
  end


=== Erb Templates

  ## You'll need to require erb in your app
  require 'erb'

  get '/' do
    erb :index
  end

Renders <tt>./views/index.erb</tt>

=== Builder Templates

The builder gem/library is required to render builder templates:

  ## You'll need to require builder in your app
  require 'builder'

  get '/' do
    content_type 'application/xml', :charset => 'utf-8'
    builder :index
  end

Renders <tt>./views/index.builder</tt>.

=== Sass Templates

The sass gem/library is required to render Sass templates:

  ## You'll need to require haml or sass in your app
  require 'sass'

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

Renders <tt>./views/stylesheet.sass</tt>.

{Sass' options}[http://haml.hamptoncatlin.com/docs/rdoc/classes/Sass.html]
can be set globally through Sinatra's configurations,
see {Options and Configurations}[http://www.sinatrarb.com/configuration.html],
and overridden on an individual basis.

  set :sass, {:style => :compact } # default Sass style is :nested

  get '/stylesheet.css' do
    content_type 'text/css', :charset => 'utf-8'
    sass :stylesheet, :sass_options => {:style => :expanded } # overridden
  end


=== Inline Templates

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

Renders the inlined template string.

=== Accessing Variables in Templates

Templates are evaluated within the same context as route handlers. Instance
variables set in route handlers are direcly accessible by templates:

  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:

  require 'rubygems'
  require 'sinatra'

  get '/' do
    haml :index
  end

  __END__

  @@ layout
  %html
    = yield

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

NOTE: In-file templates defined in the source file that requires sinatra
are automatically loaded. Call the <tt>use_in_file_templates!</tt>
method explicitly if you have in-file templates in other source files.

=== Named Templates

Templates may also be defined using the top-level <tt>template</tt> method:

  template :layout do
    "%html\n  =yield\n"
  end

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

  get '/' do
    haml :index
  end

If a template named "layout" exists, it will be used each time a template
is rendered. You can disable layouts by passing <tt>:layout => false</tt>.

  get '/' do
    haml :index, :layout => !request.xhr?
  end

== Helpers

Use the top-level <tt>helpers</tt> method to define helper methods for use in
route handlers and templates:

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

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

== Filters

Before filters are evaluated before each request within the context of the
request and can modify the request and response. Instance variables set in
filters are accessible by routes and templates:

  before do
    @note = 'Hi!'
    request.path_info = '/foo/bar/baz'
  end

  get '/foo/*' do
    @note #=> 'Hi!'
    params[:splat] #=> 'bar/baz'
  end

After filter are evaluated after each request within the context of the
request and can also modify the request and response. Instance variables
set in before filters and routes are accessible by after filters:

  after do
    puts response.status
  end

== Halting

To immediately stop a request within a filter or route use:

  halt

You can also specify a body when halting ...

  halt 'this will be the body'

Or set the status and body ...

  halt 401, 'go away!'

== Passing

A route can punt processing to the next matching route using <tt>pass</tt>:

  get '/guess/:who' do
    pass unless params[:who] == 'Frank'
    "You got me!"
  end

  get '/guess/*' do
    "You missed!"
  end

The route block is immediately exited and control continues with the next
matching route. If no matching route is found, a 404 is returned.

== Configuration

Run once, at startup, in any environment:

  configure do
    ...
  end

Run only when the environment (RACK_ENV environment variable) is set to
<tt>:production</tt>:

  configure :production do
    ...
  end

Run when the environment is set to either <tt>:production</tt> or
<tt>:test</tt>:

  configure :production, :test do
    ...
  end

== Error handling

Error handlers run within the same context as routes and before filters, which
means you get all the goodies it has to offer, like <tt>haml</tt>, <tt>erb</tt>,
<tt>halt</tt>, etc.

=== Not Found

When a <tt>Sinatra::NotFound</tt> exception is raised, or the response's status
code is 404, the <tt>not_found</tt> handler is invoked:

  not_found do
    'This is nowhere to be found'
  end

=== Error

The +error+ handler is invoked any time an exception is raised from a route
block or before filter. The exception object can be obtained from the
<tt>sinatra.error</tt> Rack variable:

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

Custom errors:

  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 get this:

  So what happened was... something bad

Sinatra installs special <tt>not_found</tt> and <tt>error</tt> handlers when
running under the development environment.

== Mime types

When using <tt>send_file</tt> or static files you may have mime types Sinatra
doesn't understand. Use +mime_type+ to register them by file extension:

  mime_type :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.

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

Sinatra tests can be written using any Rack-based testing library
or framework. {Rack::Test}[http://gitrdoc.com/brynary/rack-test] is
recommended:

  require 'my_sinatra_app'
  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

NOTE: The built-in Sinatra::Test module and Sinatra::TestHarness class
are deprecated as of the 0.9.2 release.

== Sinatra::Base - Middleware, Libraries, and Modular Apps

Defining your app at the top-level works well for micro-apps but has
considerable drawbacks when building reuseable components such as Rack
middleware, Rails metal, simple libraries with a server component, or
even Sinatra extensions. The top-level DSL pollutes the Object namespace
and assumes a micro-app style configuration (e.g., a single application
file, ./public and ./views directories, logging, exception detail page,
etc.). That's where Sinatra::Base comes into play:

  require 'sinatra/base'

  class MyApp < Sinatra::Base
    set :sessions, true
    set :foo, 'bar'

    get '/' do
      'Hello world!'
    end
  end

The MyApp class is an independent Rack component that can act as
Rack middleware, a Rack application, or Rails metal. You can +use+ or
+run+ this class from a rackup +config.ru+ file; or, control a server
component shipped as a library:

   MyApp.run! :host => 'localhost', :port => 9090

The methods available to Sinatra::Base subclasses are exactly as those
available via the top-level DSL. Most top-level apps can be converted to
Sinatra::Base components with two modifications:

* Your file should require +sinatra/base+  instead of +sinatra+;
  otherwise, all of Sinatra's DSL methods are imported into the main
  namespace.
* Put your app's routes, error handlers, filters, and options in a subclass
  of Sinatra::Base.

+Sinatra::Base+ is a blank slate. Most options are disabled by default,
including the built-in server. See {Options and Configuration}[http://sinatra.github.com/configuration.html]
for details on available options and their behavior.

SIDEBAR: Sinatra's top-level DSL is implemented using a simple delegation
system. The +Sinatra::Application+ class -- a special subclass of
Sinatra::Base -- receives all :get, :put, :post, :delete, :before,
:error, :not_found, :configure, and :set messages sent to the
top-level. Have a look at the code for yourself: here's the
{Sinatra::Delegator mixin}[http://github.com/sinatra/sinatra/blob/master/lib/sinatra/base.rb#L1064]
being {included into the main namespace}[http://github.com/sinatra/sinatra/blob/master/lib/sinatra/main.rb#L25].

== Command line

Sinatra applications can be run directly:

  ruby myapp.rb [-h] [-x] [-e ENVIRONMENT] [-p PORT] [-s HANDLER]

Options are:

  -h # help
  -p # set the port (default is 4567)
  -e # set the environment (default is development)
  -s # specify rack server/handler (default is thin)
  -x # turn on the mutex lock (default is off)

== The Bleeding Edge

If you would like to use Sinatra's latest bleeding code, create a local
clone and run your app with the <tt>sinatra/lib</tt> directory on the
<tt>LOAD_PATH</tt>:

  cd myapp
  git clone git://github.com/sinatra/sinatra.git
  ruby -Isinatra/lib myapp.rb

Alternatively, you can add the <tt>sinatra/lib</tt> directory to the
<tt>LOAD_PATH</tt> in your application:

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

  get '/about' do
    "I'm running version " + Sinatra::VERSION
  end

To update the Sinatra sources in the future:

  cd myproject/sinatra
  git pull

== More

* {Project Website}[http://sinatra.github.com/] - Additional documentation,
  news, and links to other resources.
* {Contributing}[http://sinatra.github.com/contributing.html] - Find a bug? Need
  help? Have a patch?
* {Lighthouse}[http://sinatra.lighthouseapp.com] - Issue tracking and release
  planning.
* {Twitter}[http://twitter.com/sinatra]
* {Mailing List}[http://groups.google.com/group/sinatrarb]
* {IRC: #sinatra}[irc://chat.freenode.net/#sinatra] on http://freenode.net