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:
gem install sinatra
And run with:
ruby myapp.rb
View at: http://localhost:4567
It is recommended to also run gem install thin
, which Sinatra will
pick up if available.
- Sinatra
- Table of Contents
- Routes
- Conditions
- Return Values
- Custom Route Matchers
- Static Files
- Views / Templates
- Literal Templates
- Available Template Languages
- Haml Templates
- Erb Templates
- Builder Templates
- Nokogiri Templates
- Sass Templates
- SCSS Templates
- Less Templates
- Liquid Templates
- Markdown Templates
- Textile Templates
- RDoc Templates
- AsciiDoc Templates
- Radius Templates
- Markaby Templates
- RABL Templates
- Slim Templates
- Creole Templates
- MediaWiki Templates
- CoffeeScript Templates
- Stylus Templates
- Yajl Templates
- WLang Templates
- Accessing Variables in Templates
- Templates with
yield
and nested layouts - Inline Templates
- Named Templates
- Associating File Extensions
- Adding Your Own Template Engine
- Filters
- Helpers
- Configuration
- Environments
- Error Handling
- Rack Middleware
- Testing
- Sinatra::Base - Middleware, Libraries, and Modular Apps
- Scopes and Binding
- Command Line
- Requirement
- The Bleeding Edge
- Versioning
- Further Reading
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
link '/' do
.. affiliate something ..
end
unlink '/' do
.. separate 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|
# matches "GET /hello/foo" and "GET /hello/bar"
# params[:name] is 'foo' or 'bar'
# n stores params[:name]
"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
By the way, unless you disable the path traversal attack protection (see below), the request path might be modified before matching against your routes.
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 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 or false). 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
- layout_options
- Special options only used for rendering the layout. Example: set :rdoc, :layout_options => { :views => 'views/layouts' }
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'
or 'subdir/template'.to_sym
). You must use a symbol
because otherwise rendering methods will render any strings passed to them
directly.
get '/' do
haml '%div.title Hello World'
end
Renders the template string.
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 | haml |
File Extension | .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 | builder |
File Extension | .builder |
Example | builder { |xml| xml.em "hi" } |
It also takes a block for inline templates (see example).
Dependency | nokogiri |
File Extension | .nokogiri |
Example | nokogiri { |xml| xml.em "hi" } |
It also takes a block for inline templates (see example).
Dependency | sass |
File Extension | .sass |
Example | sass :stylesheet, :style => :expanded |
Dependency | sass |
File Extension | .scss |
Example | scss :stylesheet, :style => :expanded |
Dependency | less |
File Extension | .less |
Example | less :stylesheet |
Dependency | liquid |
File Extension | .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 | Anyone of: RDiscount, RedCarpet, BlueCloth, kramdown, maruku |
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 | RedCloth |
File Extension | .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 | RDoc |
File Extension | .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 | Asciidoctor |
File Extension | .asciidoc, .adoc and .ad |
Example | asciidoc :README, :layout_engine => :erb |
Since you cannot call Ruby methods directly from an AsciiDoc template, you almost always want to pass locals to it.
Dependency | Radius |
File Extension | .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 | Markaby |
File Extension | .mab |
Example | markaby { h1 "Welcome!" } |
It also takes a block for inline templates (see example).
Dependency | Rabl |
File Extension | .rabl |
Example | rabl :index |
Dependency | Slim Lang |
File Extension | .slim |
Example | slim :index |
Dependency | Creole |
File Extension | .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 | WikiCloth |
File Extension | .mediawiki and .mw |
Example | mediawiki :wiki, :layout_engine => :erb |
It is not possible to call methods from MediaWiki markup, nor to pass locals to it. You therefore will usually use it in combination with another rendering engine:
erb :overview, :locals => { :text => mediawiki(:introduction) }
Note that you may also call the mediawiki
method from within other templates:
%h1 Hello From Haml!
%p= mediawiki(:greetings)
Since you cannot call Ruby from MediaWiki, you cannot use layouts written in
MediaWiki. However, it is possible to use another rendering engine for the
template than for the layout by passing the :layout_engine
option.
Dependency | CoffeeScript and a way to execute javascript |
File Extension | .coffee |
Example | coffee :index |
Dependency | Stylus and a way to execute javascript |
File Extension | .styl |
Example | stylus :index |
Before being able to use Stylus templates, you need to load stylus
and
stylus/tilt
first:
require 'sinatra'
require 'stylus'
require 'stylus/tilt'
get '/' do
stylus :example
end
Dependency | yajl-ruby |
File Extension | .yajl |
Example | yajl :index, :locals => { :key => 'qux' }, :callback => 'present', :variable => 'resource' |
The template source is evaluated as a Ruby string, and the
resulting json variable is converted using #to_json
:
json = { :foo => 'bar' }
json[:baz] = key
The :callback
and :variable
options can be used to decorate the rendered
object:
var resource = {"foo":"bar","baz":"qux"};
present(resource);
Dependency | WLang |
File Extension | .wlang |
Example | wlang :index, :locals => { :key => 'value' } |
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.
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.
A layout is usually just a template that calls yield
.
Such a template can be used either through the :template
option as
described above, or it can be rendered with a block as follows:
erb :post, :layout => false do
erb :index
end
This code is mostly equivalent to erb :index, :layout => :post
.
Passing blocks to rendering methods is most useful for creating nested layouts:
erb :main_layout, :layout => false do
erb :admin_layout do
erb :user
end
end
This can also be done in fewer lines of code with:
erb :admin_layout, :layout => :main_layout do
erb :user
end
Currently, the following rendering methods accept a block: erb
, haml
,
liquid
, slim
, wlang
.
Also the general render
method accepts a block.
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 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 https://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 as the routes will be 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
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.
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 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'
To share your session across other apps on subdomains of foo.com, prefix the domain with a . like this instead:
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 the 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 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:
# long polling
set :server, :thin
connections = []
get '/subscribe' do
# register a client's interest in server events
stream(:keep_open) { |out| connections << out }
# purge dead connections
connections.reject!(&:closed?)
# acknowledge
"subscribed"
end
post '/message' do
connections.each do |out|
# notify client that a new message has arrived
out << params[:message] << "\n"
# indicate client to connect again
out.close
end
# acknowledge
"message received"
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 about it in your routes and filters.
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
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 env['rack.logger']
.
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 :sessions
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 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
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:
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:
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.
According to RFC 2616, your application should behave differently if the If-Match
or If-None-Match header is set to *
, 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 post requests) are treated as new resources. You
can change this behavior by passing in a :new_resource
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 :kind
option:
etag '', :new_resource => true, :kind => :weak
For sending files, you can use the send_file
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 value: nil (default), :attachment and :inline
- length
- Content-Length header, defaults to file size.
- status
-
Status code to be sent. 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. </dd>
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_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 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
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
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
Sinatra is using Rack::Protection 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]
By default, Sinatra will only set up session based protection if :sessions
has been enabled. Sometimes you want to set up sessions on your own, though. In
that case you can get it to set up session based protections by passing the
:session
option:
use Rack::Session::Pool
set :protection, :session => true
- 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 by 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
- 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 or localhost if your `environment` is set to development.). 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 way redirect '/foo' would behave like redirect to('/foo'). Disabled per default.
- protection
- Whether or not to enable web attack protections. See protection section above.
- public_dir
- Alias for public_folder. See below.
- public_folder
- Path to the folder public files are served from. Only used if static file serving is enabled (see static setting below). Inferred from app_file 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 environment is set to "test", 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. Order indicates priority, default depends on Ruby implementation.
- sessions
- Enable cookie-based sessions support using Rack::Session::Cookie. See 'Using Sessions' section for more information.
- show_exceptions
- Show a stack trace in the browser when an exception happens. Enabled by default when environment is set to "development", disabled otherwise.
- Can also be set to :after_handler 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 Cache-Control headers to the responses. Uses the cache_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 use EventMachine.defer for processing the request.
- traps
- Whether Sinatra should handle system signals.
- views
- Path to the views folder. Inferred from app_file setting if not set.
- x_cascade
- Whether or not to set the X-Cascade header if no route matches. Defaults to true.
There are three predefined environments
: "development"
,
"production"
and "test"
. Environments can be set
through the RACK_ENV
environment variable. The default value is
"development"
. In the "development"
environment all templates are reloaded between
requests, and special not_found
and error
handlers
display stack traces in your browser.
In the "production"
and "test"
environments, templates are cached by default.
To run different environments, set the RACK_ENV
environment variable:
RACK_ENV=production ruby my_app.rb
You can use predefined methods: development?
, test?
and production?
to
check the current environment setting:
get '/' do
if settings.development?
"development!"
else
"not development!"
end
end
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 to display nice stack traces
and additional debugging information in your browser.
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, 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
Note: If you are using Sinatra in the modular style, replace Sinatra::Application
above with the class name of your app.
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, ./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 the same 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
Configuring Settings
for details on available options and their behavior.
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 |
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
file, which allows using any Rack handler:
# config.ru (run with rackup)
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
A config.ru
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
Sinatra::Base
. - You want to use Sinatra only for middleware, and not as an endpoint.
There is no need to switch to a config.ru
simply because you
switched to the modular style, and you don't have to use the 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 an optional argument:
# config.ru (run with rackup)
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
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
Sinatra.new
You can reach the scope object (the class) like this:
- Via the object passed to configure blocks (
configure { |c| ... }
) settings
from within the 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
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, patch, link, and unlink blocks
- before and after filters
- helper methods
- templates/views
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
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 extending the main object.
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 or switching to JRuby or Rubinius. Support for 1.8.7 will not be dropped before Sinatra 2.0. Ruby 1.8.6 is no longer supported.
- Ruby 1.9.2
- 1.9.2 is fully supported. Do not use 1.9.2p0, as it is known to cause segmentation faults when running Sinatra. Official support will continue at least until the release of Sinatra 1.5.
- 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. 1.9.3 will be supported until the release of Sinatra 2.0.
- Ruby 2.0.0
- 2.0.0 is fully supported and recommended. There are currently no plans to drop official support for it.
- Rubinius
- Rubinius is officially supported (Rubinius >= 2.x). It is recommended to gem install puma.
- JRuby
- The latest stable release of JRuby is officially supported. It is not recommended to use C extensions with JRuby. It is recommended to gem install trinidad.
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 2.1.0), but we can't guarantee anything, since it is constantly moving. Expect 2.1.0 to be fully supported.
Sinatra should work on any operating system supported by the chosen Ruby implementation.
If you run MacRuby, you should gem install control_tower
.
Sinatra currently doesn't run on Cardinal, SmallRuby, BlueRuby or any Ruby version prior to 1.8.7.
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.
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 'https://rubygems.org'
gem 'sinatra', :github => "sinatra/sinatra"
# 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
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 -I sinatra/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?
- Issue tracker
- Mailing List
- IRC: #sinatra on http://freenode.net
- Sinatra Book Cookbook Tutorial
- Sinatra Recipes Community contributed recipes
- API documentation for the latest release or the current HEAD on http://rubydoc.info
- CI server