sinatra/README.rdoc

= Sinatra

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

  # myapp.rb
  require 'sinatra'

  get '/' do
    'Hello world!'
  end

Install the gem and run with:

  gem install sinatra
  ruby -rubygems myapp.rb

View at: http://localhost:4567

It is recommended to also run <tt>gem install thin</tt>, which Sinatra will
pick up if available.

== Routes

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

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

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

  put '/' do
    .. replace something ..
  end

  patch '/' do
    .. modify something ..
  end

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

  options '/' do
    .. appease 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

Or with block parameters:

  get '/download/*.*' do |path, ext|
    [path, ext] # => ["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

Route patterns may have optional parameters:

  get '/posts.?:format?' do
    # matches "GET /posts" and any extension "GET /posts.json", "GET /posts.xml" etc.
  end

By the way, unless you disable the path traversal attack protection (see below),
the request path might be modified before matching against your routes.

=== Conditions

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

Other available conditions are +host_name+ and +provides+:

  get '/', :host_name => /^admin\./ do
    "Admin Area, Access denied!"
  end

  get '/', :provides => 'html' do
    haml :index
  end

  get '/', :provides => ['rss', 'atom', 'xml'] do
    builder :feed
  end

You can easily define your own conditions:

  set(:probability) { |value| condition { rand <= value } }

  get '/win_a_car', :probability => 0.1 do
    "You won!"
  end

  get '/win_a_car' do
    "Sorry, you lost."
  end

For a condition that takes multiple values use a splat:

  set(:auth) do |*roles|   # <- notice the splat here
    condition do
      unless logged_in? && roles.any? {|role| current_user.in_role? role }
        redirect "/login/", 303
      end
    end
  end

  get "/my/account/", :auth => [:user, :admin] do
    "Your Account Details"
  end

  get "/only/admin/", :auth => :admin do
    "Only admins are allowed here!"
  end

=== Return Values

The return value of a route block determines at least the response body passed
on to the HTTP client, or at least the next middleware in the Rack stack.
Most commonly, this is a string, as in the above examples. But other values are
also accepted.

You can return any object that would either be a valid Rack response, Rack
body object or HTTP status code:

* An Array with three elements: <tt>[status (Fixnum), headers (Hash), response
  body (responds to #each)]</tt>
* An Array with two elements: <tt>[status (Fixnum), response body (responds to
  #each)]</tt>
* An object that responds to <tt>#each</tt> and passes nothing but strings to
  the given block
* A Fixnum representing the status code

That way we can, for instance, easily implement a streaming example:

    class Stream
      def each
        100.times { |i| yield "#{i}\n" }
      end
    end

    get('/') { Stream.new }

You can also use the +stream+ helper method (described below) to reduce boiler
plate and embed the streaming logic in the route.

=== Custom Route Matchers

As shown above, Sinatra ships with built-in support for using String patterns
and regular expressions as route matches. However, it does not stop there. You
can easily define your own matchers:

  class AllButPattern
    Match = Struct.new(:captures)

    def initialize(except)
      @except   = except
      @captures = Match.new([])
    end

    def match(str)
      @captures unless @except === str
    end
  end

  def all_but(pattern)
    AllButPattern.new(pattern)
  end

  get all_but("/index") do
    # ...
  end

Note that the above example might be over-engineered, as it can also be
expressed as:

  get // do
    pass if request.path_info == "/index"
    # ...
  end

Or, using negative look ahead:

  get %r{^(?!/index$)} do
    # ...
  end

== Static Files

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

  set :public_folder, 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>.

Use the <tt>:static_cache_control</tt> setting (see below) to add
<tt>Cache-Control</tt> header info.

== Views / Templates

Each template language is exposed via its own rendering method. These
methods simply return a string:

  get '/' do
    erb :index
  end

This renders <tt>views/index.erb</tt>.

Instead of a template name, you can also just pass in the template content
directly:

  get '/' do
    code = "<%= Time.now %>"
    erb code
  end

Templates take a second argument, the options hash:

  get '/' do
    erb :index, :layout => :post
  end

This will render <tt>views/index.erb</tt> embedded in the
<tt>views/post.erb</tt> (default is <tt>views/layout.erb</tt>, if it exists).

Any options not understood by Sinatra will be passed on to the template
engine:

  get '/' do
    haml :index, :format => :html5
  end

You can also set options per template language in general:

  set :haml, :format => :html5

  get '/' do
    haml :index
  end

Options passed to the render method override options set via +set+.

Available Options:

[locals]
  List of locals passed to the document. Handy with partials.
  Example: <tt>erb "<%= foo %>", :locals => {:foo => "bar"}</tt>

[default_encoding]
  String encoding to use if uncertain. Defaults to
  <tt>settings.default_encoding</tt>.

[views]
  Views folder to load templates from. Defaults to <tt>settings.views</tt>.

[layout]
  Whether to use a layout (+true+ or +false+), if it's a Symbol, specifies
  what template to use. Example: <tt>erb :index, :layout => !request.xhr?</tt>

[content_type]
  Content-Type the template produces, default depends on template language.

[scope]
  Scope to render template under. Defaults to the application instance. If you
  change this, instance variables and helper methods will not be available.

[layout_engine]
  Template engine to use for rendering the layout. Useful for languages that
  do not support layouts otherwise. Defaults to the engine used for the
  template. Example: <tt>set :rdoc, :layout_engine => :erb</tt>

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

  set :views, settings.root + '/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>). You must use a symbol because
otherwise rendering methods will render any strings passed to them
directly.

=== Available Template Languages

Some languages have multiple implementations. To specify what implementation
to use (and to be thread-safe), you should simply require it first:

  require 'rdiscount' # or require 'bluecloth'
  get('/') { markdown :index }

=== Haml Templates

Dependency::        {haml}[http://haml.info/]
File Extension::   <tt>.haml</tt>
Example::           <tt>haml :index, :format => :html5</tt>

=== Erb Templates

Dependency::        {erubis}[http://www.kuwata-lab.com/erubis/] or
                    erb (included in Ruby)
File Extensions::   <tt>.erb</tt>, <tt>.rhtml</tt> or <tt>.erubis</tt> (Erubis
                    only)
Example::           <tt>erb :index</tt>

=== Builder Templates

Dependency::        {builder}[http://builder.rubyforge.org/]
File Extension::   <tt>.builder</tt>
Example::           <tt>builder { |xml| xml.em "hi" }</tt>

It also takes a block for inline templates (see example).

=== Nokogiri Templates

Dependency::        {nokogiri}[http://nokogiri.org/]
File Extension::   <tt>.nokogiri</tt>
Example::           <tt>nokogiri { |xml| xml.em "hi" }</tt>

It also takes a block for inline templates (see example).

=== Sass Templates

Dependency::        {sass}[http://sass-lang.com/]
File Extension::   <tt>.sass</tt>
Example::           <tt>sass :stylesheet, :style => :expanded</tt>

=== SCSS Templates

Dependency::        {sass}[http://sass-lang.com/]
File Extension::   <tt>.scss</tt>
Example::           <tt>scss :stylesheet, :style => :expanded</tt>

=== Less Templates

Dependency::        {less}[http://www.lesscss.org/]
File Extension::   <tt>.less</tt>
Example::           <tt>less :stylesheet</tt>

=== Liquid Templates

Dependency::        {liquid}[http://www.liquidmarkup.org/]
File Extension::   <tt>.liquid</tt>
Example::           <tt>liquid :index, :locals => { :key => 'value' }</tt>

Since you cannot call Ruby methods (except for +yield+) from a Liquid
template, you almost always want to pass locals to it.

=== Markdown Templates

Dependency::        {rdiscount}[https://github.com/rtomayko/rdiscount],
                    {redcarpet}[https://github.com/tanoku/redcarpet],
                    {bluecloth}[http://deveiate.org/projects/BlueCloth],
                    {kramdown}[http://kramdown.rubyforge.org/] *or*
                    {maruku}[http://maruku.rubyforge.org/]
File Extensions::   <tt>.markdown</tt>, <tt>.mkd</tt> and <tt>.md</tt>
Example::           <tt>markdown :index, :layout_engine => :erb</tt>

It is not possible to call methods from markdown, nor to pass locals to it.
You therefore will usually use it in combination with another rendering
engine:

  erb :overview, :locals => { :text => markdown(:introduction) }

Note that you may also call the +markdown+ method from within other templates:

  %h1 Hello From Haml!
  %p= markdown(:greetings)

Since you cannot call Ruby from Markdown, you cannot use layouts written in
Markdown. However, it is possible to use another rendering engine for the
template than for the layout by passing the <tt>:layout_engine</tt> option.

=== Textile Templates

Dependency::        {RedCloth}[http://redcloth.org/]
File Extension::   <tt>.textile</tt>
Example::           <tt>textile :index, :layout_engine => :erb</tt>

It is not possible to call methods from textile, nor to pass locals to it. You
therefore will usually use it in combination with another rendering engine:

  erb :overview, :locals => { :text => textile(:introduction) }

Note that you may also call the +textile+ method from within other templates:

  %h1 Hello From Haml!
  %p= textile(:greetings)

Since you cannot call Ruby from Textile, you cannot use layouts written in
Textile. However, it is possible to use another rendering engine for the
template than for the layout by passing the <tt>:layout_engine</tt> option.

=== RDoc Templates

Dependency::        {rdoc}[http://rdoc.rubyforge.org/]
File Extension::   <tt>.rdoc</tt>
Example::           <tt>rdoc :README, :layout_engine => :erb</tt>

It is not possible to call methods from rdoc, nor to pass locals to it. You
therefore will usually use it in combination with another rendering engine:

  erb :overview, :locals => { :text => rdoc(:introduction) }

Note that you may also call the +rdoc+ method from within other templates:

  %h1 Hello From Haml!
  %p= rdoc(:greetings)

Since you cannot call Ruby from RDoc, you cannot use layouts written in
RDoc. However, it is possible to use another rendering engine for the
template than for the layout by passing the <tt>:layout_engine</tt> option.

=== Radius Templates

Dependency::        {radius}[http://radius.rubyforge.org/]
File Extension::   <tt>.radius</tt>
Example::           <tt>radius :index, :locals => { :key => 'value' }</tt>

Since you cannot call Ruby methods directly from a Radius template, you almost
always want to pass locals to it.

=== Markaby Templates

Dependency::        {markaby}[http://markaby.github.com/]
File Extension::   <tt>.mab</tt>
Example::           <tt>markaby { h1 "Welcome!" }</tt>

It also takes a block for inline templates (see example).

=== RABL Templates

Dependency::        {rabl}[https://github.com/nesquena/rabl]
File Extension::   <tt>.rabl</tt>
Example::           <tt>rabl :index</tt>

=== Slim Templates

Dependency::        {slim}[http://slim-lang.com/]
File Extension::   <tt>.slim</tt>
Example::           <tt>slim :index</tt>

=== Creole Templates

Dependency::        {creole}[https://github.com/minad/creole]
File Extension::   <tt>.creole</tt>
Example::           <tt>creole :wiki, :layout_engine => :erb</tt>

It is not possible to call methods from creole, nor to pass locals to it. You
therefore will usually use it in combination with another rendering engine:

  erb :overview, :locals => { :text => creole(:introduction) }

Note that you may also call the +creole+ method from within other templates:

  %h1 Hello From Haml!
  %p= creole(:greetings)

Since you cannot call Ruby from Creole, you cannot use layouts written in
Creole. However, it is possible to use another rendering engine for the
template than for the layout by passing the <tt>:layout_engine</tt> option.

=== CoffeeScript Templates

Dependency::        {coffee-script}[https://github.com/josh/ruby-coffee-script]
                    and a {way to execute javascript}[https://github.com/sstephenson/execjs/blob/master/README.md#readme]
File Extension::   <tt>.coffee</tt>
Example::           <tt>coffee :index</tt>

=== Yajl Templates

Dependency::        {yajl-ruby}[https://github.com/brianmario/yajl-ruby]
File Extension::   <tt>.yajl</tt>
Example::           <tt>yajl :index, :locals => { :key => 'qux' }, :callback => 'present', :variable => 'resource' </tt>

The template source is evaluated as a Ruby string, and the resulting json variable is converted #to_json.

  json = { :foo => 'bar' }
  json[:baz] = key

The <tt>:callback</tt> and <tt>:variable</tt> options can be used to decorate the rendered object.

  var resource = {"foo":"bar","baz":"qux"}; present(resource);

=== WLang Templates

Dependency::        {wlang}[https://github.com/blambeau/wlang/]
File Extension::   <tt>.wlang</tt>
Example::           <tt>wlang :index, :locals => { :key => 'value' }</tt>

Since calling ruby methods is not idiomatic in wlang, you almost always want to pass locals
to it. Layouts written in wlang and +yield+ are supported, though.

=== Embedded Templates

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

Renders the embedded template string.

=== Accessing Variables in Templates

Templates are evaluated within the same context as route handlers. Instance
variables set in route handlers are directly 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= bar.name', :locals => { :bar => 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 '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 <tt>enable :inline_templates</tt> explicitly if you
have inline 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 individually disable layouts by passing
<tt>:layout => false</tt> or disable them by default via
<tt>set :haml, :layout => false</tt>:

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

=== Associating File Extensions

To associate a file extension with a template engine, use
<tt>Tilt.register</tt>. For instance, if you like to use the file extension
+tt+ for Textile templates, you can do the following:

  Tilt.register :tt, Tilt[:textile]

=== Adding Your Own Template Engine

First, register your engine with Tilt, then create a rendering method:

  Tilt.register :myat, MyAwesomeTemplateEngine

  helpers do
    def myat(*args) render(:myat, *args) end
  end

  get '/' do
    myat :index
  end

Renders <tt>./views/index.myat</tt>. See https://github.com/rtomayko/tilt to
learn more about Tilt.

== Filters

Before filters are evaluated before each request within the same
context as the routes will be 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 filters are evaluated after each request within the same context 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

Note: Unless you use the +body+ method rather than just returning a String from
the routes, the body will not yet be available in the after filter, since it is
generated later on.

Filters optionally take 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

Like routes, filters also take conditions:

  before :agent => /Songbird/ do
    # ...
  end

  after '/blog/*', :host_name => 'example.com' do
    # ...
  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

Alternatively, helper methods can be separately defined in a module:

  module FooUtils
    def foo(name) "#{name}foo" end
  end

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

  helpers FooUtils, BarUtils

The effect is the same as including the modules in the application class.

=== Using Sessions

A session is used to keep state during requests. If activated, you have one
session hash per user session:

  enable :sessions

  get '/' do
    "value = " << session[:value].inspect
  end

  get '/:value' do
    session[:value] = params[:value]
  end

Note that <tt>enable :sessions</tt> actually stores all data in a cookie. This
might not always be what you want (storing lots of data will increase your
traffic, for instance). You can use any Rack session middleware: in order to
do so, do *not* call <tt>enable :sessions</tt>, but instead pull in your
middleware of choice as you would any other middleware:

  use Rack::Session::Pool, :expire_after => 2592000

  get '/' do
    "value = " << session[:value].inspect
  end

  get '/:value' do
    session[:value] = params[:value]
  end

To improve security, the session data in the cookie is signed with a session
secret. A random secret is generated for you by Sinatra. However, since this
secret will change with every start of your application, you might want to
set the secret yourself, so all your application instances share it:

  set :session_secret, 'super secret'

If you want to configure it further, you may also store a hash with options in
the +sessions+ setting:

  set :sessions, :domain => 'foo.com'

=== 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'

It is of course possible to combine a template with +halt+:

  halt erb(:error)

=== 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.

=== Triggering Another Route

Sometimes +pass+ is not what you want, instead you would like to get the result
of calling another route. Simply use +call+ to achieve this:

  get '/foo' do
    status, headers, body = call env.merge("PATH_INFO" => '/bar')
    [status, headers, body.map(&:upcase)]
  end

  get '/bar' do
    "bar"
  end

Note that in the example above, you would ease testing and increase performance
by simply moving <tt>"bar"</tt> into a helper used by both <tt>/foo</tt>
and <tt>/bar</tt>.

If you want the request to be sent to the same application instance rather than
a duplicate, use <tt>call!</tt> instead of <tt>call</tt>.

Check out the Rack specification if you want to learn more about <tt>call</tt>.

=== Setting Body, Status Code and Headers

It is possible and recommended to set the status code and response body with the
return value of the route block. However, in some scenarios you might want to
set the body at an arbitrary point in the execution flow. You can do so with the
+body+ helper method. If you do so, you can use that method from there on to
access the body:

  get '/foo' do
    body "bar"
  end

  after do
    puts body
  end

It is also possible to pass a block to +body+, which will be executed by the
Rack handler (this can be used to implement streaming, see "Return Values").

Similar to the body, you can also set the status code and headers:

  get '/foo' do
    status 418
    headers \
      "Allow"   => "BREW, POST, GET, PROPFIND, WHEN",
      "Refresh" => "Refresh: 20; http://www.ietf.org/rfc/rfc2324.txt"
    body "I'm a tea pot!"
  end

Like +body+, +headers+ and +status+ with no arguments can be used to access
their current values.

=== Streaming Responses

Sometimes you want to start sending out data while still generating parts of
the response body. In extreme examples, you want to keep sending data until
the client closes the connection. You can use the +stream+ helper to avoid
creating your own wrapper:

  get '/' do
    stream do |out|
      out << "It's gonna be legen -\n"
      sleep 0.5
      out << " (wait for it) \n"
      sleep 1
      out << "- dary!\n"
    end
  end

This allows you to implement streaming APIs,
{Server Sent Events}[http://dev.w3.org/html5/eventsource/] and can be used as
the basis for {WebSockets}[http://en.wikipedia.org/wiki/WebSocket]. It can also be
used to increase throughput if some but not all content depends on a slow
resource.

Note that the streaming behavior, especially the number of concurrent requests,
highly depends on the web server used to serve the application. Some servers,
like WEBRick, might not even support streaming at all. If the server does not
support streaming, the body will be sent all at once after the block passed to
+stream+ finishes executing. Streaming does not work at all with Shotgun.

If the optional parameter is set to +keep_open+, it will not call +close+ on
the stream object, allowing you to close it at any later point in the
execution flow. This only works on evented servers, like Thin and Rainbows.
Other servers will still close the stream:

  set :server, :thin
  connections = []

  get '/' do
    # keep stream open
    stream(:keep_open) { |out| connections << out }
  end

  post '/' do
    # write to all open streams
    connections.each { |out| out << params[:message] << "\n" }
    "message sent"
  end

=== Logging

In the request scope, the +logger+ helper exposes a +Logger+ instance:

  get '/' do
    logger.info "loading data"
    # ...
  end

This logger will automatically take your Rack handler's logging settings into
account. If logging is disabled, this method will return a dummy object, so
you do not have to worry in your routes and filters about it.

Note that logging is only enabled for <tt>Sinatra::Application</tt> by
default, so if you inherit from <tt>Sinatra::Base</tt>, you probably want to
enable it yourself:

  class MyApp < Sinatra::Base
    configure :production, :development do
      enable :logging
    end
  end

To avoid any logging middleware to be set up, set the +logging+ setting to
+nil+. However, keep in mind that +logger+ will in that case return +nil+. A
common use case is when you want to set your own logger. Sinatra will use
whatever it will find in <tt>env['rack.logger']</tt>.

=== 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:

  configure do
    mime_type :foo, 'text/foo'
  end

You can also use it with the +content_type+ helper:

  get '/' do
    content_type :foo
    "foo foo foo"
  end

=== Generating URLs

For generating URLs you should use the +url+ helper method, for instance, in
Haml:

  %a{:href => url('/foo')} foo

It takes reverse proxies and Rack routers into account, if present.

This method is also aliased to +to+ (see below for an example).

=== Browser Redirect

You can trigger a browser redirect with the +redirect+ helper method:

  get '/foo' do
    redirect to('/bar')
  end

Any additional parameters are handled like arguments passed to +halt+:

  redirect to('/bar'), 303
  redirect 'http://google.com', 'wrong place, buddy'

You can also easily redirect back to the page the user came from with
<tt>redirect back</tt>:

  get '/foo' do
    "<a href='/bar'>do something</a>"
  end

  get '/bar' do
    do_something
    redirect back
  end

To pass arguments with a redirect, either add them to the query:

  redirect to('/bar?sum=42')

Or use a session:

  enable :sessions

  get '/foo' do
    session[:secret] = 'foo'
    redirect to('/bar')
  end

  get '/bar' do
    session[:secret]
  end

=== Cache Control

Setting your headers correctly is the foundation for proper HTTP caching.

You can easily set the Cache-Control header like this:

  get '/' do
    cache_control :public
    "cache it!"
  end

Pro tip: Set up caching in a before filter:

  before do
    cache_control :public, :must_revalidate, :max_age => 60
  end

If you are using the +expires+ helper to set the corresponding header,
<tt>Cache-Control</tt> will be set automatically for you:

  before do
    expires 500, :public, :must_revalidate
  end

To properly use caches, you should consider using +etag+ or +last_modified+.
It is recommended to call those helpers *before* doing any heavy lifting, as they
will immediately flush a response if the client already has the current
version in its cache:

  get '/article/:id' do
    @article = Article.find params[:id]
    last_modified @article.updated_at
    etag @article.sha1
    erb :article
  end

It is also possible to use a
{weak ETag}[http://en.wikipedia.org/wiki/HTTP_ETag#Strong_and_weak_validation]:

  etag @article.sha1, :weak

These helpers will not do any caching for you, but rather feed the necessary
information to your cache. If you are looking for a quick reverse-proxy caching
solution, try {rack-cache}[http://rtomayko.github.com/rack-cache/]:

  require "rack/cache"
  require "sinatra"

  use Rack::Cache

  get '/' do
    cache_control :public, :max_age => 36000
    sleep 5
    "hello"
  end

Use the <tt>:static_cache_control</tt> setting (see below) to add
<tt>Cache-Control</tt> header info to static files.

According to RFC 2616 your application should behave differently if the If-Match
or If-None-Match header is set to <tt>*</tt> depending on whether the resource
requested is already in existence. Sinatra assumes resources for safe (like get)
and idempotent (like put) requests are already in existence, whereas other
resources (for instance for post requests), are treated as new resources. You
can change this behavior by passing in a <tt>:new_resource</tt> option:

  get '/create' do
    etag '', :new_resource => true
    Article.create
    erb :new_article
  end

If you still want to use a weak ETag, pass in a <tt>:kind</tt> option:

  etag '', :new_resource => true, :kind => :weak

=== Sending Files

For sending files, you can use the <tt>send_file</tt> helper method:

  get '/' do
    send_file 'foo.png'
  end

It also takes options:

  send_file 'foo.png', :type => :jpg

The options are:

[filename]
  file name, in response, defaults to the real file name.

[last_modified]
  value for Last-Modified header, defaults to the file's mtime.

[type]
  content type to use, guessed from the file extension if missing.

[disposition]
  used for Content-Disposition, possible values: +nil+ (default),
  <tt>:attachment</tt> and <tt>:inline</tt>

[length]
  Content-Length header, defaults to file size.

[status]
  Status code to be send. Useful when sending a static file as an error page.

If supported by the Rack handler, other means than streaming from the Ruby
process will be used. If you use this helper method, Sinatra will automatically
handle range requests.

=== Accessing the Request Object

The incoming request object can be accessed from request level (filter, routes,
error handlers) through the <tt>request</tt> method:

  # app running on http://example.com/example
  get '/foo' do
    t = %w[text/css text/html application/javascript]
    request.accept              # ['text/html', '*/*']
    request.accept? 'text/xml'  # true
    request.preferred_type(t)   # 'text/html'
    request.body                # request body sent by the client (see below)
    request.scheme              # "http"
    request.script_name         # "/example"
    request.path_info           # "/foo"
    request.port                # 80
    request.request_method      # "GET"
    request.query_string        # ""
    request.content_length      # length of request.body
    request.media_type          # media type of request.body
    request.host                # "example.com"
    request.get?                # true (similar methods for other verbs)
    request.form_data?          # false
    request["some_param"]       # value of some_param parameter. [] is a shortcut to the params hash.
    request.referrer            # the referrer of the client or '/'
    request.user_agent          # user agent (used by :agent condition)
    request.cookies             # hash of browser cookies
    request.xhr?                # is this an ajax request?
    request.url                 # "http://example.com/example/foo"
    request.path                # "/example/foo"
    request.ip                  # client IP address
    request.secure?             # false (would be true over ssl)
    request.forwarded?          # true (if running behind a reverse proxy)
    request.env                 # raw env hash handed in by Rack
  end

Some options, like <tt>script_name</tt> or <tt>path_info</tt>, can also be
written:

  before { request.path_info = "/" }

  get "/" do
    "all requests end up here"
  end

The <tt>request.body</tt> is an IO or StringIO object:

  post "/api" do
    request.body.rewind  # in case someone already read it
    data = JSON.parse request.body.read
    "Hello #{data['name']}!"
  end

=== Attachments

You can use the +attachment+ helper to tell the browser the response should be
stored on disk rather than displayed in the browser:

  get '/' do
    attachment
    "store it!"
  end

You can also pass it a file name:

  get '/' do
    attachment "info.txt"
    "store it!"
  end

=== Dealing with Date and Time

Sinatra offers a +time_for+ helper method that generates a Time object
from the given value. It is also able to convert +DateTime+, +Date+ and
similar classes:

  get '/' do
    pass if Time.now > time_for('Dec 23, 2012')
    "still time"
  end

This method is used internally by +expires+, +last_modified+ and akin. You can
therefore easily extend the behavior of those methods by overriding +time_for+
in your application:

  helpers do
    def time_for(value)
      case value
      when :yesterday then Time.now - 24*60*60
      when :tomorrow  then Time.now + 24*60*60
      else super
      end
    end
  end

  get '/' do
    last_modified :yesterday
    expires :tomorrow
    "hello"
  end

=== Looking Up Template Files

The <tt>find_template</tt> helper is used to find template files for rendering:

  find_template settings.views, 'foo', Tilt[:haml] do |file|
    puts "could be #{file}"
  end

This is not really useful. But it is useful that you can actually override this
method to hook in your own lookup mechanism. For instance, if you want to be
able to use more than one view directory:

  set :views, ['views', 'templates']

  helpers do
    def find_template(views, name, engine, &block)
      Array(views).each { |v| super(v, name, engine, &block) }
    end
  end

Another example would be using different directories for different engines:

  set :views, :sass => 'views/sass', :haml => 'templates', :default => 'views'

  helpers do
    def find_template(views, name, engine, &block)
      _, folder = views.detect { |k,v| engine == Tilt[k] }
      folder ||= views[:default]
      super(folder, name, engine, &block)
    end
  end

You can also easily wrap this up in an extension and share with others!

Note that <tt>find_template</tt> does not check if the file really exists but
rather calls the given block for all possible paths. This is not a performance
issue, since +render+ will use +break+ as soon as a file is found. Also,
template locations (and content) will be cached if you are not running in
development mode. You should keep that in mind if you write a really crazy
method.

== Configuration

Run once, at startup, in any environment:

  configure do
    # setting one option
    set :option, 'value'

    # setting multiple options
    set :a => 1, :b => 2

    # same as `set :option, true`
    enable :option

    # same as `set :option, false`
    disable :option

    # you can also have dynamic settings with blocks
    set(:css_dir) { File.join(views, 'css') }
  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

You can access those options via <tt>settings</tt>:

  configure do
    set :foo, 'bar'
  end

  get '/' do
    settings.foo? # => true
    settings.foo  # => 'bar'
    ...
  end

=== Configuring attack protection

Sinatra is using
{Rack::Protection}[https://github.com/rkh/rack-protection#readme] to defend
your application against common, opportunistic attacks. You can easily disable
this behavior (which will open up your application to tons of common
vulnerabilities):

  disable :protection

To skip a single defense layer, set +protection+ to an options hash:

  set :protection, :except => :path_traversal

You can also hand in an array in order to disable a list of protections:

  set :protection, :except => [:path_traversal, :session_hijacking]

=== Available Settings

[absolute_redirects]   If disabled, Sinatra will allow relative redirects,
                       however, Sinatra will no longer conform with RFC 2616
                       (HTTP 1.1), which only allows absolute redirects.

                       Enable if your app is running behind a reverse proxy that
                       has not been set up properly. Note that the +url+ helper
                       will still produce absolute URLs, unless you pass in
                       +false+ as the second parameter.

                       Disabled per default.

[add_charsets]         mime types the <tt>content_type</tt> helper will
                       automatically add the charset info to.

                       You should add to it rather than overriding this option:

                         settings.add_charsets << "application/foobar"

[app_file]             Path to the main application file, used to detect project
                       root, views and public folder and inline templates.

[bind]                 IP address to bind to (default: 0.0.0.0).
                       Only used for built-in server.

[default_encoding]     encoding to assume if unknown
                       (defaults to <tt>"utf-8"</tt>).

[dump_errors]          display errors in the log.

[environment]          current environment, defaults to <tt>ENV['RACK_ENV']</tt>,
                       or <tt>"development"</tt> if not available.

[logging]              use the logger.

[lock]                 Places a lock around every request, only running
                       processing on request per Ruby process concurrently.

                       Enabled if your app is not thread-safe.
                       Disabled per default.

[method_override]      use <tt>_method</tt> magic to allow put/delete forms in
                       browsers that don't support it.

[port]                 Port to listen on. Only used for built-in server.

[prefixed_redirects]   Whether or not to insert <tt>request.script_name</tt>
                       into redirects if no absolute path is given. That way
                       <tt>redirect '/foo'</tt> would behave like
                       <tt>redirect to('/foo')</tt>. Disabled per default.

[protection]           Whether or not to enable web attack protections. See
                       protection section above.

[public_dir]           Alias for <tt>public_folder</tt>. See below.

[public_folder]        Path to the folder public files are served from. Only
                       used if static file serving is enabled (see
                       <tt>static</tt> setting below). Inferred from
                       <tt>app_file</tt> setting if not set.

[reload_templates]     whether or not to reload templates between requests.
                       Enabled in development mode.

[root]                 Path to project root folder. Inferred from +app_file+
                       setting if not set.

[raise_errors]         raise exceptions (will stop application). Enabled
                       by default when <tt>environment</tt> is set to
                       <tt>"test"</tt>, disabled otherwise.

[run]                  if enabled, Sinatra will handle starting the web server,
                       do not enable if using rackup or other means.

[running]              is the built-in server running now?
                       do not change this setting!

[server]               server or list of servers to use for built-in server.
                       defaults to ['thin', 'mongrel', 'webrick'], order
                       indicates priority.

[sessions]             enable cookie-based sessions support using
                       <tt>Rack::Session::Cookie</tt>. See 'Using Sessions'
                       section for more information.

[show_exceptions]      show a stack trace in the browser when an exception
                       happens. Enabled by default when <tt>environment</tt>
                       is set to <tt>"development"</tt>, disabled otherwise.
                       Can also be set to <tt>:after_handler</tt> to trigger
                       app-specified error handling before showing a stack
                       trace in the browser.

[static]               Whether Sinatra should handle serving static files.
                       Disable when using a server able to do this on its own.
                       Disabling will boost performance.
                       Enabled per default in classic style, disabled for
                       modular apps.

[static_cache_control] When Sinatra is serving static files, set this to add
                       <tt>Cache-Control</tt> headers to the responses. Uses the
                       +cache_control+ helper. Disabled by default.
                       Use an explicit array when setting multiple values:
                       <tt>set :static_cache_control, [:public, :max_age => 300]</tt>

[threaded]             If set to +true+, will tell Thin to use
                       <tt>EventMachine.defer</tt> for processing the request.

[views]                Path to the views folder. Inferred from <tt>app_file</tt>
                       setting if not set.

== Environments

There are three predefined +environments+: <tt>"development"</tt>,
<tt>"production"</tt> and <tt>"test"</tt>. Environments can be set
through the +RACK_ENV+ environment variable. The default value is
<tt>"development"</tt>. In the <tt>"development"</tt> environment all templates are reloaded between
requests, and special <tt>not_found</tt> and <tt>error</tt> handlers 
display stack traces in your browser.
In the <tt>"production"</tt> and <tt>"test"</tt> environments, templates are cached by default.

To run different environments use the <tt>-e</tt> option:

  ruby my_app.rb -e [ENVIRONMENT]

You can use predefined methods: +development?+, +test?+ and +production?+ to
check the current environment setting.

== 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 a 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...' + 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 an 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 <tt>not_found</tt> and <tt>error</tt> handlers when
running under the development environment.

== 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 these components automatically based on configuration so you
typically don't have to +use+ them explicitly.

You can find useful middleware in
{rack}[https://github.com/rack/rack/tree/master/lib/rack],
{rack-contrib}[https://github.com/rack/rack-contrib#readme],
with {CodeRack}[http://coderack.org/] or in the
{Rack wiki}[https://github.com/rack/rack/wiki/List-of-Middleware].

== Testing

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

  require 'my_sinatra_app'
  require 'test/unit'
  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

== 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 reusable components such as Rack
middleware, Rails metal, simple libraries with a server component, or even
Sinatra extensions. The top-level assumes a micro-app style configuration
(e.g., a single application file, <tt>./public</tt> and <tt>./views</tt>
directories, logging, exception detail page, etc.). That's where
<tt>Sinatra::Base</tt> comes into play:

  require 'sinatra/base'

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

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

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

* Your file should require <tt>sinatra/base</tt> 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 <tt>Sinatra::Base</tt>.

<tt>Sinatra::Base</tt> 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.

=== Modular vs. Classic Style

Contrary to common belief, there is nothing wrong with the classic style. If it
suits your application, you do not have to switch to a modular application.

The main disadvantage of using the classic style rather than the modular style is that
you will only have one Sinatra application per Ruby process. If you plan to use
more than one, switch to the modular style. There is no reason you cannot mix
the modular and the classic styles.

If switching from one style to the other, you should be aware of slightly
different default settings:

  Setting             Classic                 Modular

  app_file            file loading sinatra    file subclassing Sinatra::Base
  run                 $0 == app_file          false
  logging             true                    false
  method_override     true                    false
  inline_templates    true                    false
  static              true                    false


=== Serving a Modular Application

There are two common options for starting a modular app, actively starting with
<tt>run!</tt>:

  # my_app.rb
  require 'sinatra/base'

  class MyApp < Sinatra::Base
    # ... app code here ...

    # start the server if ruby file executed directly
    run! if app_file == $0
  end

Start with:

  ruby my_app.rb

Or with a <tt>config.ru</tt> file, which allows using any Rack handler:

  # config.ru
  require './my_app'
  run MyApp

Run:

  rackup -p 4567

=== Using a Classic Style Application with a config.ru

Write your app file:

  # app.rb
  require 'sinatra'

  get '/' do
    'Hello world!'
  end

And a corresponding <tt>config.ru</tt>:

  require './app'
  run Sinatra::Application

=== When to use a config.ru?

A <tt>config.ru</tt> file is recommended if:

* You want to deploy with a different Rack handler (Passenger, Unicorn,
  Heroku, ...).
* You want to use more than one subclass of <tt>Sinatra::Base</tt>.
* You want to use Sinatra only for middleware, and not as an endpoint.

<b>There is no need to switch to a <tt>config.ru</tt> simply because you
switched to the modular style, and you don't have to use the modular style for running
with a <tt>config.ru</tt>.</b>

=== Using Sinatra as Middleware

Not only is Sinatra able to use other Rack middleware, any Sinatra application
can in turn be added in front of any Rack endpoint as middleware itself. This
endpoint could be another Sinatra application, or any other Rack-based
application (Rails/Ramaze/Camping/...):

  require 'sinatra/base'

  class LoginScreen < Sinatra::Base
    enable :sessions

    get('/login') { haml :login }

    post('/login') do
      if params[:name] == 'admin' && params[:password] == 'admin'
        session['user_name'] = params[:name]
      else
        redirect '/login'
      end
    end
  end

  class MyApp < Sinatra::Base
    # middleware will run before filters
    use LoginScreen

    before do
      unless session['user_name']
        halt "Access denied, please <a href='/login'>login</a>."
      end
    end

    get('/') { "Hello #{session['user_name']}." }
  end

=== Dynamic Application Creation

Sometimes you want to create new applications at runtime without having to
assign them to a constant, you can do this with <tt>Sinatra.new</tt>:

  require 'sinatra/base'
  my_app = Sinatra.new { get('/') { "hi" } }
  my_app.run!

It takes the application to inherit from as an optional argument:

  # config.ru
  require 'sinatra/base'

  controller = Sinatra.new do
    enable :logging
    helpers MyHelpers
  end

  map('/a') do
    run Sinatra.new(controller) { get('/') { 'a' } }
  end

  map('/b') do
    run Sinatra.new(controller) { get('/') { 'b' } }
  end

This is especially useful for testing Sinatra extensions or using Sinatra in
your own library.

This also makes using Sinatra as middleware extremely easy:

  require 'sinatra/base'

  use Sinatra do
    get('/') { ... }
  end

  run RailsProject::Application

== Scopes and Binding

The scope you are currently in determines what methods and variables are
available.

=== Application/Class Scope

Every Sinatra application corresponds to a subclass of <tt>Sinatra::Base</tt>.
If you are using the top-level DSL (<tt>require 'sinatra'</tt>), then this
class is <tt>Sinatra::Application</tt>, otherwise it is the subclass you
created explicitly. At class level you have methods like +get+ or +before+, but
you cannot access the +request+ or +session+ objects, as there is only a
single application class for all requests.

Options created via +set+ are methods at class level:

    class MyApp < Sinatra::Base
      # Hey, I'm in the application scope!
      set :foo, 42
      foo # => 42

      get '/foo' do
        # Hey, I'm no longer in the application scope!
      end
    end

You have the application scope binding inside:

* Your application class body
* Methods defined by extensions
* The block passed to +helpers+
* Procs/blocks used as value for +set+
* The block passed to <tt>Sinatra.new</tt>

You can reach the scope object (the class) like this:

* Via the object passed to configure blocks (<tt>configure { |c| ... }</tt>)
* +settings+ from within the request scope

=== Request/Instance Scope

For every incoming request, a new instance of your application class is
created and all handler blocks run in that scope. From within this scope you
can access the +request+ and +session+ objects or call rendering methods like
+erb+ or +haml+. You can access the application scope from within the request
scope via the +settings+ helper:

  class MyApp < Sinatra::Base
    # Hey, I'm in the application scope!
    get '/define_route/:name' do
      # Request scope for '/define_route/:name'
      @value = 42

      settings.get("/#{params[:name]}") do
        # Request scope for "/#{params[:name]}"
        @value # => nil (not the same request)
      end

      "Route defined!"
    end
  end

You have the request scope binding inside:

* get/head/post/put/delete/options blocks
* before/after filters
* helper methods
* templates/views

=== Delegation Scope

The delegation scope just forwards methods to the class scope. However, it
does not behave exactly like the class scope, as you do not have the class
binding. Only methods explicitly marked for delegation are available, and you
do not share variables/state with the class scope (read: you have a different
+self+). You can explicitly add method delegations by calling
<tt>Sinatra::Delegator.delegate :method_name</tt>.

You have the delegate scope binding inside:

* The top level binding, if you did <tt>require "sinatra"</tt>
* An object extended with the <tt>Sinatra::Delegator</tt> mixin

Have a look at the code for yourself: here's the
{Sinatra::Delegator mixin}[https://github.com/sinatra/sinatra/blob/ca06364/lib/sinatra/base.rb#L1609-1633]
being {extending the main object}[https://github.com/sinatra/sinatra/blob/ca06364/lib/sinatra/main.rb#L28-30].

== 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)

== Requirement

The following Ruby versions are officially supported:

[ Ruby 1.8.7 ]
  1.8.7 is fully supported, however, if nothing is keeping you from it, we
  recommend upgrading to 1.9.2 or switching to JRuby or Rubinius. Support for
  1.8.7 will not be dropped before Sinatra 2.0 and Ruby 2.0 except maybe in
  the unlikely event of 1.8.8 being released. Even then, we might continue
  supporting it. <b>Ruby 1.8.6 is no longer supported.</b> If you want to run
  with 1.8.6, downgrade to Sinatra 1.2, which will receive bug fixes until
  Sinatra 1.4.0 is released.

[ Ruby 1.9.2 ]
  1.9.2 is fully supported and recommended. Do not use 1.9.2p0, as it is known to
  cause segmentation faults when running Sinatra. Support will continue at least
  until the release of Ruby 1.9.4/2.0 and support for the latest 1.9 release
  will continue as long as it is still supported by the Ruby core team.

[ Ruby 1.9.3 ]
  1.9.3 is fully supported and recommended. Please note that switching to 1.9.3
  from an earlier version will invalidate all sessions.

[ Rubinius ]
  Rubinius is officially supported (Rubinius >= 1.2.4), everything works, including
  all template languages. The upcoming 2.0 release is supported as
  well, including 1.9 mode.

[ JRuby ]
  JRuby is officially supported (JRuby >= 1.6.7). No issues with third party
  template libraries are known, however, if you choose to use JRuby, please
  look into JRuby rack handlers, as the Thin web server is not fully supported
  on JRuby. JRuby's support for C extensions is still experimental, which only
  affects RDiscount, Redcarpet, RedCloth and Yajl templates as well as Thin
  and Mongrel at the moment.

We also keep an eye on upcoming Ruby versions.

The following Ruby implementations are not officially supported but still are
known to run Sinatra:

* Older versions of JRuby and Rubinius
* Ruby Enterprise Edition
* MacRuby, Maglev, IronRuby
* Ruby 1.9.0 and 1.9.1 (but we do recommend against using those)

Not being officially supported means if things only break there and not on a
supported platform, we assume it's not our issue but theirs.

We also run our CI against ruby-head (the upcoming 2.0.0) and the 1.9.4
branch, but we can't guarantee anything, since it is constantly moving. Expect
both 1.9.4p0 and 2.0.0p0 to be supported.

Sinatra should work on any operating system supported by the chosen Ruby
implementation.

Sinatra currently doesn't run on Cardinal, SmallRuby, BlueRuby or any
Ruby version prior to 1.8.7.

== The Bleeding Edge

If you would like to use Sinatra's latest bleeding-edge code, feel free to run your
application against the master branch, it should be rather stable.

We also push out prerelease gems from time to time, so you can do a

  gem install sinatra --pre

To get some of the latest features.

=== With Bundler

If you want to run your application with the latest Sinatra, using
{Bundler}[http://gembundler.com/] is the recommended way.

First, install bundler, if you haven't:

  gem install bundler

Then, in your project directory, create a +Gemfile+:

  source :rubygems
  gem 'sinatra', :git => "git://github.com/sinatra/sinatra.git"

  # other dependencies
  gem 'haml'                    # for instance, if you use haml
  gem 'activerecord', '~> 3.0'  # maybe you also need ActiveRecord 3.x

Note that you will have to list all your application's dependencies in the +Gemfile+.
Sinatra's direct dependencies (Rack and Tilt) will, however, be automatically
fetched and added by Bundler.

Now you can run your app like this:

  bundle exec ruby myapp.rb

=== Roll Your Own

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

To update the Sinatra sources in the future:

  cd myapp/sinatra
  git pull

=== Install Globally

You can build the gem on your own:

  git clone git://github.com/sinatra/sinatra.git
  cd sinatra
  rake sinatra.gemspec
  rake install

If you install gems as root, the last step should be

  sudo rake install

== Versioning

Sinatra follows {Semantic Versioning}[http://semver.org/], both SemVer and
SemVerTag.

== Further Reading

* {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
* {Sinatra Book}[http://sinatra-book.gittr.com] Cookbook Tutorial
* {Sinatra Recipes}[http://recipes.sinatrarb.com/] Community
  contributed recipes
* API documentation for the {latest release}[http://rubydoc.info/gems/sinatra]
  or the {current HEAD}[http://rubydoc.info/github/sinatra/sinatra] on
  http://rubydoc.info
* {CI server}[http://travis-ci.org/sinatra/sinatra]