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: localhost:4567
It is recommended to also run gem install thin
, which Sinatra will pick up if available.
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 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
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
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
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:
[status (Fixnum), headers (Hash), response body (responds to #each)]
-
An Array with two elements:
[status (Fixnum), response body (responds to #each)]
-
An object that responds to
#each
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.
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 are served from the ./public
directory. You can specify a different location by setting the :public_folder
option:
set :public_folder, 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
.
Use the :static_cache_control
setting (see below) to add Cache-Control
header info.
Each template language is exposed as via its own rendering method. These methods simply return a string:
get '/' do erb :index end
This renders views/index.erb
.
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 views/index.erb
embedded in the views/post.erb
(default is views/layout.erb
, 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:
erb "<%= foo %>", :locals => {:foo => "bar"}
- default_encoding
-
String encoding to use if uncertain. Defaults to
settings.default_encoding
. - views
-
Views folder to load templates from. Defaults to
settings.views
. - layout
-
Whether to use a layout (
true
orfalse
), if it’s a Symbol, specifies what template to use. Example:erb :index, :layout => !request.xhr?
- 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:
set :rdoc, :layout_engine => :erb
Templates are assumed to be located directly under the ./views
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 :'subdir/template'
). You must use a symbol because otherwise rendering methods will render any strings passed to them directly.
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 }
- Dependency
- File Extensions
-
.haml
- Example
-
haml :index, :format => :html5
- Dependency
-
erubis or erb (included in Ruby)
- File Extensions
-
.erb
,.rhtml
or.erubis
(Erubis only) - Example
-
erb :index
- Dependency
- File Extensions
-
.builder
- Example
-
builder { |xml| xml.em "hi" }
It also takes a block for inline templates (see example).
- Dependency
- File Extensions
-
.nokogiri
- Example
-
nokogiri { |xml| xml.em "hi" }
It also takes a block for inline templates (see example).
- Dependency
- File Extensions
-
.sass
- Example
-
sass :stylesheet, :style => :expanded
- Dependency
- File Extensions
-
.scss
- Example
-
scss :stylesheet, :style => :expanded
- Dependency
- File Extensions
-
.less
- Example
-
less :stylesheet
- Dependency
- File Extensions
-
.liquid
- Example
-
liquid :index, :locals => { :key => 'value' }
Since you cannot call Ruby methods (except for yield
) from a Liquid template, you almost always want to pass locals to it.
- Dependency
- File Extensions
-
.markdown
,.mkd
and.md
- Example
-
markdown :index, :layout_engine => :erb
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 :layout_engine
option.
- Dependency
- File Extensions
-
.textile
- Example
-
textile :index, :layout_engine => :erb
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 :layout_engine
option.
- Dependency
- File Extensions
-
.rdoc
- Example
-
rdoc :README, :layout_engine => :erb
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 :layout_engine
option.
- Dependency
- File Extensions
-
.radius
- Example
-
radius :index, :locals => { :key => 'value' }
Since you cannot call Ruby methods directly from a Radius template, you almost always want to pass locals to it.
- Dependency
- File Extensions
-
.mab
- Example
-
markaby { h1 "Welcome!" }
It also takes a block for inline templates (see example).
- Dependency
- File Extensions
-
.slim
- Example
-
slim :index
- Dependency
- File Extensions
-
.creole
- Example
-
creole :wiki, :layout_engine => :erb
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 :layout_engine
option.
- Dependency
- File Extensions
-
.coffee
- Example
-
coffee :index
get '/' do haml '%div.title Hello World' end
Renders the embedded template string.
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.
Templates may be defined at the end of the source file:
require 'sinatra' get '/' do haml :index end __END__
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.
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 individually disable layouts by passing :layout => false
or disable them by default via set :haml, :layout => false
:
get '/' do haml :index, :layout => !request.xhr? end
To associate a file extension with a template engine, use Tilt.register
. For instance, if you like to use the file extension tt
for Textile templates, you can do the following:
Tilt.register :tt, Tilt[:textile]
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 ./views/index.myat
. See github.com/rtomayko/tilt to learn more about Tilt.
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
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
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 enable :sessions
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 enable :sessions
, 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 generate 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'
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)
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.
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 "bar"
into a helper used by both /foo
and /bar
.
If you want the request to be sent to the same application instance rather than a duplicate, use call!
instead of call
.
Check out the Rack specification if you want to learn more about call
.
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.
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 and can be used as basis for WebSockets. 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 request, 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
finished executing.
If the optional parameter is set to false
, 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(false) { |out| connections << out } end post '/' do # write to all open streams connections.each { |out| out << params[:message] << "\n" } "message sent" end
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 Sinatra::Application
by default, so if you inherit from Sinatra::Base
, you probably want to enable it yourself:
class MyApp < Sinatra::Base configure(:production, :development) do enable :logging end end
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:
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
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).
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 redirect back
:
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 :session get '/foo' do session[:secret] = 'foo' redirect to('/bar') end get '/bar' do session[:secret] end
Setting your headers correctly is the foundation for proper HTTP caching.
You can easily set the Cache-Control header with 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, Cache-Control
will be set automatically for you:
before do expires 500, :public, :must_revalidate end
To properly use caches, you should consider using etag
and last_modified
. It is recommended to call those helpers before doing 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:
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 caching solutions, try rack-cache:
require "rack/cache" require "sinatra" use Rack::Cache get '/' do cache_control :public, :max_age => 36000 sleep 5 "hello" end
Use the :static_cache_control
setting (see below) to add Cache-Control
header info to static files.
For sending files, you can use the send_file
helper method:
get '/' do send_file 'foo.png' end
It also takes a couple of 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),:attachment
and:inline
- length
-
Content-Length header, defaults to file size.
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.
The incoming request object can be accessed from request level (filter, routes, error handlers) through the request
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_HEADER"] # value of SOME_HEADER header 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 script_name
or path_info
, can also be written:
before { request.path_info = "/" } get "/" do "all requests end up here" end
The request.body
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
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
The find_template
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 find_template
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.
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 :production
:
configure :production do ... end
Run when the environment is set to either :production
or :test
:
configure :production, :test do ... end
You can access those options via settings
:
configure do set :foo, 'bar' end get '/' do settings.foo? # => true settings.foo # => 'bar' ... end
- 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 infalse
as second parameter.Disabled per default.
- add_charsets
-
mime types the
content_type
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
-
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
"utf-8"
). - dump_errors
-
display errors in the log.
- environment
-
current environment, defaults to
ENV['RACK_ENV']
, or"development"
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
_method
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
request.script_name
into redirects if no absolute path is given. That wayredirect '/foo'
would behave likeredirect to('/foo')
. Disabled per default. - public_folder
-
folder public files are served from
- reload_templates
-
whether or not to reload templates between requests. Enabled in development mode.
- root
-
project root folder.
- raise_errors
-
raise exceptions (will stop application).
- 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.
- show_exceptions
-
show 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
Cache-Control
headers to the responses. Uses thecache_control
helper. Disabled by default. Use an explicit array when setting multiple values:set :static_cache_control, [:public, :max_age => 300]
- threaded
-
If set to
true
, will tell Thin to useEventMachine.defer
for processing the request. - views
-
views folder.
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.
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
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...' + 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 not_found
and error
handlers when running under the development environment.
Sinatra rides on Rack, 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 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, rack-contrib, with CodeRack or in the Rack wiki.
Sinatra tests can be written using any Rack-based testing library or framework. Rack::Test 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
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 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 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 ofsinatra
; 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 for details on available options and their behavior.
Contrary to common belief, there is nothing wrong with classic style. If it suits your application, you do not have to switch to a modular application.
There are only two downsides compared with modular style:
-
You may only have one Sinatra application per Ruby process. If you plan to use more, switch to modular style.
-
Classic style pollutes Object with delegator methods. If you plan to ship your application in a library/gem, switch to modular style.
There is no reason you cannot mix modular and classic style.
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
There are two common options for starting a modular app, actively starting with run!
:
# 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 config.ru
, which allows using any Rack handler:
# config.ru require './my_app' run MyApp
Run:
rackup -p 4567
Write your app file:
# app.rb require 'sinatra' get '/' do 'Hello world!' end
And a corresponding config.ru
:
require './app' run Sinatra::Application
Good signs you probably want to use a config.ru
:
-
You want to deploy with a different Rack handler (Passenger, Unicorn, Heroku, …).
-
You want to use more than one subclass of
Sinatra::Base
. -
You want to use Sinatra only for middleware, but not as endpoint.
There is no need to switch to a config.ru
only because you switched to modular style, and you don’t have to use modular style for running with a config.ru
.
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
Sometimes you want to create new applications at runtime without having to assign them to a constant, you can do this with Sinatra.new
:
require 'sinatra/base' my_app = Sinatra.new { get('/') { "hi" } } my_app.run!
It takes the application to inherit from as 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
The scope you are currently in determines what methods and variables are available.
Every Sinatra application corresponds to a subclass of Sinatra::Base
. If you are using the top-level DSL (require 'sinatra'
), then this class is Sinatra::Application
, otherwise it is the subclass you created explicitly. At class level you have methods like get
or before
, but you cannot access the request
object or the session
, as there only is 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
Sinatra.new
You can reach the scope object (the class) like this:
-
Via the object passed to configure blocks (
configure { |c| ... }
) -
settings
from within request 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
object 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
The delegation scope just forwards methods to the class scope. However, it does not behave 100% 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 Sinatra::Delegator.delegate :method_name
.
You have the delegate scope binding inside:
-
The top level binding, if you did
require "sinatra"
-
An object extended with the
Sinatra::Delegator
mixin
Have a look at the code for yourself: here’s the Sinatra::Delegator mixin being included into the main namespace.
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 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.
- Ruby 1.9.2
-
1.9.2 is supported and recommended. Note that Radius and Markaby are currently not 1.9 compatible. Do not use 1.9.2p0, it is known to cause segmentation faults when running Sinatra.
- Rubinius
-
Rubinius is officially supported (Rubinius >= 1.2.3), everything, including all template languages, works.
- JRuby
-
JRuby is officially supported (JRuby >= 1.6.1). 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 and Redcarpet at the moment.
Ruby 1.8.6 is no longer supported. 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.
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
-
MacRuby, Maglev, IronRuby
-
Ruby 1.9.0 and 1.9.1
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 1.9.3), but we can’t guarantee anything, since it is constantly moving. Expect 1.9.3p0 to be supported.
Sinatra should work on any operating system supported by the chosen Ruby implementation.
If you would like to use Sinatra’s latest bleeding 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.
If you want to run your application with the latest Sinatra, using Bundler 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 applications dependencies in there. 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
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
To update the Sinatra sources in the future:
cd myapp/sinatra git pull
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
Sinatra follows Semantic Versioning, both SemVer and SemVerTag.
-
Project Website - Additional documentation, news, and links to other resources.
-
Contributing - Find a bug? Need help? Have a patch?
-
#sinatra on freenode.net
-
Sinatra Book Cookbook Tutorial
-
Sinatra Book Contrib Community contributed recipes
-
API documentation for the latest release or the current HEAD on rubydoc.info