= Sinatra
Sinatra is a DSL for quickly creating web applications in Ruby with minimal
effort:
# myapp.rb
require 'rubygems'
require 'sinatra'
get '/' do
'Hello world!'
end
Install the gem and run with:
sudo gem install sinatra
ruby myapp.rb
View at: http://localhost:4567
== Routes
In Sinatra, a route is an HTTP method paired with an URL matching pattern.
Each route is associated with a block:
get '/' do
.. show something ..
end
post '/' do
.. create something ..
end
put '/' do
.. update something ..
end
delete '/' do
.. annihilate something ..
end
Routes are matched in the order they are defined. The first route that
matches the request is invoked.
Route patterns may include named parameters, accessible via the
<tt>params</tt> hash:
get '/hello/:name' do
# matches "GET /hello/foo" and "GET /hello/bar"
# params[:name] is 'foo' or 'bar'
"Hello #{params[:name]}!"
end
You can also access named parameters via block parameters:
get '/hello/:name' do |n|
"Hello #{n}!"
end
Route patterns may also include splat (or wildcard) parameters, accessible
via the <tt>params[:splat]</tt> array.
get '/say/*/to/*' do
# matches /say/hello/to/world
params[:splat] # => ["hello", "world"]
end
get '/download/*.*' do
# matches /download/path/to/file.xml
params[:splat] # => ["path/to/file", "xml"]
end
Route matching with Regular Expressions:
get %r{/hello/([\w]+)} do
"Hello, #{params[:captures].first}!"
end
Or with a block parameter:
get %r{/hello/([\w]+)} do |c|
"Hello, #{c}!"
end
Routes may include a variety of matching conditions, such as the user agent:
get '/foo', :agent => /Songbird (\d\.\d)[\d\/]*?/ do
"You're using Songbird version #{params[:agent][0]}"
end
get '/foo' do
# Matches non-songbird browsers
end
== Static Files
Static files are served from the <tt>./public</tt> directory. You can specify
a different location by setting the <tt>:public</tt> option:
set :public, File.dirname(__FILE__) + '/static'
Note that the public directory name is not included in the URL. A file
<tt>./public/css/style.css</tt> is made available as
<tt>http://example.com/css/style.css</tt>.
== Views / Templates
Templates are assumed to be located directly under the <tt>./views</tt>
directory. To use a different views directory:
set :views, File.dirname(__FILE__) + '/templates'
One important thing to remember is that you always have to reference
templates with symbols, even if they're in a subdirectory (in this
case use <tt>:'subdir/template'</tt>). Rendering methods will render
any strings passed to them directly.
=== Haml Templates
The haml gem/library is required to render HAML templates:
## You'll need to require haml in your app
require 'haml'
get '/' do
haml :index
end
Renders <tt>./views/index.haml</tt>.
{Haml's options}[http://haml.hamptoncatlin.com/docs/rdoc/classes/Haml.html]
can be set globally through Sinatra's configurations,
see {Options and Configurations}[http://www.sinatrarb.com/configuration.html],
and overridden on an individual basis.
set :haml, {:format => :html5 } # default Haml format is :xhtml
get '/' do
haml :index, :haml_options => {:format => :html4 } # overridden
end
=== Erb Templates
## You'll need to require erb in your app
require 'erb'
get '/' do
erb :index
end
Renders <tt>./views/index.erb</tt>
=== Erubis
The erubis gem/library is required to render builder templates:
## You'll need to require erubis in your app
require 'erubis'
get '/' do
erubis :index
end
Renders <tt>./views/index.erubis</tt>
=== Builder Templates
The builder gem/library is required to render builder templates:
## You'll need to require builder in your app
require 'builder'
get '/' do
content_type 'application/xml', :charset => 'utf-8'
builder :index
end
Renders <tt>./views/index.builder</tt>.
=== Sass Templates
The sass gem/library is required to render Sass templates:
## You'll need to require haml or sass in your app
require 'sass'
get '/stylesheet.css' do
content_type 'text/css', :charset => 'utf-8'
sass :stylesheet
end
Renders <tt>./views/stylesheet.sass</tt>.
{Sass' options}[http://haml.hamptoncatlin.com/docs/rdoc/classes/Sass.html]
can be set globally through Sinatra's configurations,
see {Options and Configurations}[http://www.sinatrarb.com/configuration.html],
and overridden on an individual basis.
set :sass, {:style => :compact } # default Sass style is :nested
get '/stylesheet.css' do
content_type 'text/css', :charset => 'utf-8'
sass :stylesheet, :style => :expanded # overridden
end
=== Inline Templates
get '/' do
haml '%div.title Hello World'
end
Renders the inlined template string.
=== Accessing Variables in Templates
Templates are evaluated within the same context as route handlers. Instance
variables set in route handlers are direcly accessible by templates:
get '/:id' do
@foo = Foo.find(params[:id])
haml '%h1= @foo.name'
end
Or, specify an explicit Hash of local variables:
get '/:id' do
foo = Foo.find(params[:id])
haml '%h1= foo.name', :locals => { :foo => foo }
end
This is typically used when rendering templates as partials from within
other templates.
=== Inline Templates
Templates may be defined at the end of the source file:
require 'rubygems'
require 'sinatra'
get '/' do
haml :index
end
__END__
@@ layout
%html
= yield
@@ index
%div.title Hello world!!!!!
NOTE: Inline templates defined in the source file that requires sinatra
are automatically loaded. Call `enable :inline_templates` explicitly if you
have inline templates in other source files.
=== Named Templates
Templates may also be defined using the top-level <tt>template</tt> method:
template :layout do
"%html\n =yield\n"
end
template :index do
'%div.title Hello World!'
end
get '/' do
haml :index
end
If a template named "layout" exists, it will be used each time a template
is rendered. You can disable layouts by passing <tt>:layout => false</tt>.
get '/' do
haml :index, :layout => !request.xhr?
end
== Helpers
Use the top-level <tt>helpers</tt> method to define helper methods for use in
route handlers and templates:
helpers do
def bar(name)
"#{name}bar"
end
end
get '/:name' do
bar(params[:name])
end
== Filters
Before filters are evaluated before each request within the context of the
request and can modify the request and response. Instance variables set in
filters are accessible by routes and templates:
before do
@note = 'Hi!'
request.path_info = '/foo/bar/baz'
end
get '/foo/*' do
@note #=> 'Hi!'
params[:splat] #=> 'bar/baz'
end
After filter are evaluated after each request within the context of the
request and can also modify the request and response. Instance variables
set in before filters and routes are accessible by after filters:
after do
puts response.status
end
== Halting
To immediately stop a request within a filter or route use:
halt
You can also specify the status when halting ...
halt 410
Or the body ...
halt 'this will be the body'
Or both ...
halt 401, 'go away!'
With headers ...
halt 402, {'Content-Type' => 'text/plain'}, 'revenge'
== Passing
A route can punt processing to the next matching route using <tt>pass</tt>:
get '/guess/:who' do
pass unless params[:who] == 'Frank'
'You got me!'
end
get '/guess/*' do
'You missed!'
end
The route block is immediately exited and control continues with the next
matching route. If no matching route is found, a 404 is returned.
== Configuration
Run once, at startup, in any environment:
configure do
...
end
Run only when the environment (RACK_ENV environment variable) is set to
<tt>:production</tt>:
configure :production do
...
end
Run when the environment is set to either <tt>:production</tt> or
<tt>:test</tt>:
configure :production, :test do
...
end
== Error handling
Error handlers run within the same context as routes and before filters, which
means you get all the goodies it has to offer, like <tt>haml</tt>, <tt>erb</tt>,
<tt>halt</tt>, etc.
=== Not Found
When a <tt>Sinatra::NotFound</tt> exception is raised, or the response's status
code is 404, the <tt>not_found</tt> handler is invoked:
not_found do
'This is nowhere to be found'
end
=== Error
The +error+ handler is invoked any time an exception is raised from a route
block or a filter. The exception object can be obtained from the
<tt>sinatra.error</tt> Rack variable:
error do
'Sorry there was a nasty error - ' + env['sinatra.error'].name
end
Custom errors:
error MyCustomError do
'So what happened was...' + request.env['sinatra.error'].message
end
Then, if this happens:
get '/' do
raise MyCustomError, 'something bad'
end
You get this:
So what happened was... something bad
Alternatively, you can install error handler for a status code:
error 403 do
'Access forbidden'
end
get '/secret' do
403
end
Or a range:
error 400..510 do
'Boom'
end
Sinatra installs special <tt>not_found</tt> and <tt>error</tt> handlers when
running under the development environment.
== Mime types
When using <tt>send_file</tt> or static files you may have mime types Sinatra
doesn't understand. Use +mime_type+ to register them by file extension:
mime_type :foo, 'text/foo'
You can also use it with the +content_type+ helper:
content_type :foo
== Rack Middleware
Sinatra rides on Rack[http://rack.rubyforge.org/], a minimal standard
interface for Ruby web frameworks. One of Rack's most interesting capabilities
for application developers is support for "middleware" -- components that sit
between the server and your application monitoring and/or manipulating the
HTTP request/response to provide various types of common functionality.
Sinatra makes building Rack middleware pipelines a cinch via a top-level
+use+ method:
require 'sinatra'
require 'my_custom_middleware'
use Rack::Lint
use MyCustomMiddleware
get '/hello' do
'Hello World'
end
The semantics of +use+ are identical to those defined for the
Rack::Builder[http://rack.rubyforge.org/doc/classes/Rack/Builder.html] DSL
(most frequently used from rackup files). For example, the +use+ method
accepts multiple/variable args as well as blocks:
use Rack::Auth::Basic do |username, password|
username == 'admin' && password == 'secret'
end
Rack is distributed with a variety of standard middleware for logging,
debugging, URL routing, authentication, and session handling. Sinatra uses
many of of these components automatically based on configuration so you
typically don't have to +use+ them explicitly.
== Testing
Sinatra tests can be written using any Rack-based testing library
or framework. {Rack::Test}[http://gitrdoc.com/brynary/rack-test] is
recommended:
require 'my_sinatra_app'
require 'rack/test'
class MyAppTest < Test::Unit::TestCase
include Rack::Test::Methods
def app
Sinatra::Application
end
def test_my_default
get '/'
assert_equal 'Hello World!', last_response.body
end
def test_with_params
get '/meet', :name => 'Frank'
assert_equal 'Hello Frank!', last_response.body
end
def test_with_rack_env
get '/', {}, 'HTTP_USER_AGENT' => 'Songbird'
assert_equal "You're using Songbird!", last_response.body
end
end
NOTE: The built-in Sinatra::Test module and Sinatra::TestHarness class
are deprecated as of the 0.9.2 release.
== Sinatra::Base - Middleware, Libraries, and Modular Apps
Defining your app at the top-level works well for micro-apps but has
considerable drawbacks when building reuseable components such as Rack
middleware, Rails metal, simple libraries with a server component, or
even Sinatra extensions. The top-level DSL pollutes the Object namespace
and assumes a micro-app style configuration (e.g., a single application
file, ./public and ./views directories, logging, exception detail page,
etc.). That's where Sinatra::Base comes into play:
require 'sinatra/base'
class MyApp < Sinatra::Base
set :sessions, true
set :foo, 'bar'
get '/' do
'Hello world!'
end
end
The MyApp class is an independent Rack component that can act as
Rack middleware, a Rack application, or Rails metal. You can +use+ or
+run+ this class from a rackup +config.ru+ file; or, control a server
component shipped as a library:
MyApp.run! :host => 'localhost', :port => 9090
The methods available to Sinatra::Base subclasses are exactly as those
available via the top-level DSL. Most top-level apps can be converted to
Sinatra::Base components with two modifications:
* Your file should require +sinatra/base+ instead of +sinatra+;
otherwise, all of Sinatra's DSL methods are imported into the main
namespace.
* Put your app's routes, error handlers, filters, and options in a subclass
of Sinatra::Base.
+Sinatra::Base+ is a blank slate. Most options are disabled by default,
including the built-in server. See {Options and Configuration}[http://sinatra.github.com/configuration.html]
for details on available options and their behavior.
SIDEBAR: Sinatra's top-level DSL is implemented using a simple delegation
system. The +Sinatra::Application+ class -- a special subclass of
Sinatra::Base -- receives all :get, :put, :post, :delete, :before,
:error, :not_found, :configure, and :set messages sent to the
top-level. Have a look at the code for yourself: here's the
{Sinatra::Delegator mixin}[http://github.com/sinatra/sinatra/blob/master/lib/sinatra/base.rb#L1064]
being {included into the main namespace}[http://github.com/sinatra/sinatra/blob/master/lib/sinatra/main.rb#L25].
== Command line
Sinatra applications can be run directly:
ruby myapp.rb [-h] [-x] [-e ENVIRONMENT] [-p PORT] [-h HOST] [-s HANDLER]
Options are:
-h # help
-p # set the port (default is 4567)
-h # set the host (default is 0.0.0.0)
-e # set the environment (default is development)
-s # specify rack server/handler (default is thin)
-x # turn on the mutex lock (default is off)
== The Bleeding Edge
If you would like to use Sinatra's latest bleeding code, create a local
clone and run your app with the <tt>sinatra/lib</tt> directory on the
<tt>LOAD_PATH</tt>:
cd myapp
git clone git://github.com/sinatra/sinatra.git
ruby -Isinatra/lib myapp.rb
Alternatively, you can add the <tt>sinatra/lib</tt> directory to the
<tt>LOAD_PATH</tt> in your application:
$LOAD_PATH.unshift File.dirname(__FILE__) + '/sinatra/lib'
require 'rubygems'
require 'sinatra'
get '/about' do
"I'm running version " + Sinatra::VERSION
end
To update the Sinatra sources in the future:
cd myproject/sinatra
git pull
== More
* {Project Website}[http://sinatra.github.com/] - Additional documentation,
news, and links to other resources.
* {Contributing}[http://sinatra.github.com/contributing.html] - Find a bug? Need
help? Have a patch?
* {Lighthouse}[http://sinatra.lighthouseapp.com] - Issue tracking and release
planning.
* {Twitter}[http://twitter.com/sinatra]
* {Mailing List}[http://groups.google.com/group/sinatrarb]
* {IRC: #sinatra}[irc://chat.freenode.net/#sinatra] on http://freenode.net
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