= 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 params 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 params[:splat] 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 ./public directory. You can specify a different location by setting the :public option: set :public, File.dirname(__FILE__) + '/static' Note that the public directory name is not included in the URL. A file ./public/css/style.css is made available as http://example.com/css/style.css. == Views / Templates Templates are assumed to be located directly under the ./views 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 :'subdir/template'). 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 ./views/index.haml. {Haml's options}[http://haml-lang.com/docs/yardoc/file.HAML_REFERENCE.html#options] 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 ./views/index.erb === Erubis The erubis gem/library is required to render erubis templates: ## You'll need to require erubis in your app require 'erubis' get '/' do erubis :index end Renders ./views/index.erubis === 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 ./views/index.builder. === 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 ./views/stylesheet.sass. {Sass' options}[http://sass-lang.com/docs/yardoc/file.SASS_REFERENCE.html#options] 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, :style => :expanded # overridden end === Scss Templates The sass gem/library is required to render Scss 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' scss :stylesheet end Renders ./views/stylesheet.scss. {Scss' options}[http://sass-lang.com/docs/yardoc/file.SASS_REFERENCE.html#options] 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 :scss, {:style => :compact } # default Scss style is :nested get '/stylesheet.css' do content_type 'text/css', :charset => 'utf-8' scss :stylesheet, :style => :expanded # overridden end === Less Templates The less gem/library is required to render Less templates: ## You'll need to require less in your app require 'less' get '/stylesheet.css' do content_type 'text/css', :charset => 'utf-8' less :stylesheet end Renders ./views/stylesheet.less. === 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. === Inline 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: Inline templates defined in the source file that requires sinatra are automatically loaded. Call `enable :inline_templates` explicitly if you have inline templates in other source files. === Named Templates Templates may also be defined using the top-level template 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 :layout => false. get '/' do haml :index, :layout => !request.xhr? end == Helpers Use the top-level helpers 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 Filters optionally taking a pattern, causing them to be evaluated only if the request path matches that pattern: before '/protected/*' do authenticate! end after '/create/:slug' do |slug| session[:last_slug] = slug end == Halting To immediately stop a request within a filter or route use: halt You can also specify the status when halting ... halt 410 Or the body ... halt 'this will be the body' Or both ... halt 401, 'go away!' With headers ... halt 402, {'Content-Type' => 'text/plain'}, 'revenge' == Passing A route can punt processing to the next matching route using pass: 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 :production: configure :production do ... end Run when the environment is set to either :production or :test: 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 haml, erb, halt, etc. === Not Found When a Sinatra::NotFound exception is raised, or the response's status code is 404, the not_found 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 a filter. The exception object can be obtained from the sinatra.error 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 Alternatively, you can install error handler for a status code: error 403 do 'Access forbidden' end get '/secret' do 403 end Or a range: error 400..510 do 'Boom' end Sinatra installs special not_found and error handlers when running under the development environment. == Mime types When using send_file 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' You can also use it with the +content_type+ helper: content_type :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/ceac46f0bc129a6e994a06100aa854f606fe5992/lib/sinatra/base.rb#L1128] being {included into the main namespace}[http://github.com/sinatra/sinatra/blob/ceac46f0bc129a6e994a06100aa854f606fe5992/lib/sinatra/main.rb#L28] == Command line Sinatra applications can be run directly: ruby myapp.rb [-h] [-x] [-e ENVIRONMENT] [-p PORT] [-o HOST] [-s HANDLER] Options are: -h # help -p # set the port (default is 4567) -o # set the host (default is 0.0.0.0) -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 sinatra/lib directory on the LOAD_PATH: cd myapp git clone git://github.com/sinatra/sinatra.git ruby -Isinatra/lib myapp.rb Alternatively, you can add the sinatra/lib directory to the LOAD_PATH 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://www.sinatrarb.com/] - Additional documentation, news, and links to other resources. * {Contributing}[http://www.sinatrarb.com/contributing] - Find a bug? Need help? Have a patch? * {Issue tracker}[http://github.com/sinatra/sinatra/issues] * {Twitter}[http://twitter.com/sinatra] * {Mailing List}[http://groups.google.com/group/sinatrarb/topics] * {IRC: #sinatra}[irc://chat.freenode.net/#sinatra] on http://freenode.net