Sinatra
¶ ↑
Sinatra
is a DSL for quickly creating web applications in Ruby with minimal effort:
# myapp.rb require 'sinatra' get '/' do 'Hello world!' end
Install the gem:
gem install sinatra
And run with:
ruby myapp.rb
View at: localhost:4567
The code you changed will not take effect until you restart the server. Please restart the server every time you change or use sinatra/reloader.
It is recommended to also run gem install puma
, which Sinatra
will pick up if available.
Table of Contents¶ ↑
-
-
-
-
{Templates with
yield
and nested layouts}[#templates-with-yield-and-nested-layouts]
-
Routes¶ ↑
In Sinatra
, a route is an HTTP method paired with a URL-matching pattern. Each route is associated with a block:
get '/' do .. show something .. end post '/' do .. create something .. end put '/' do .. replace something .. end patch '/' do .. modify something .. end delete '/' do .. annihilate something .. end options '/' do .. appease something .. end 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.
Routes with trailing slashes are different from the ones without:
get '/foo' do # Does not match "GET /foo/" end
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 /\/hello\/([\w]+)/ do "Hello, #{params['captures'].first}!" end
Or with a block parameter:
get %r{/hello/([\w]+)} do |c| # Matches "GET /meta/hello/world", "GET /hello/world/1234" etc. "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 also utilize query parameters:
get '/posts' do # matches "GET /posts?title=foo&author=bar" title = params['title'] author = params['author'] # uses title and author variables; query is optional to the /posts route 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.
You may customize the Mustermann options used for a given route by passing in a :mustermann_opts
hash:
get '\A/posts\z', :mustermann_opts => { :type => :regexp, :check_anchors => false } do # matches /posts exactly, with explicit anchoring "If you match an anchored pattern clap your hands!" end
It looks like a condition, but it isn’t one! These options will be merged into the global :mustermann_opts
hash described below.
Conditions¶ ↑
Routes may include a variety of matching conditions, such as the user agent:
get '/foo', :agent => /Songbird (\d\.\d)[\d\/]*?/ do "You're using Songbird version #{params['agent'][0]}" end get '/foo' do # Matches non-songbird browsers end
Other available conditions are host_name
and provides
:
get '/', :host_name => /^admin\./ do "Admin Area, Access denied!" end get '/', :provides => 'html' do haml :index end get '/', :provides => ['rss', 'atom', 'xml'] do builder :feed end
provides
searches the request’s Accept header.
You can easily define your own conditions:
set(:probability) { |value| condition { rand <= value } } get '/win_a_car', :probability => 0.1 do "You won!" end get '/win_a_car' do "Sorry, you lost." end
For a condition that takes multiple values use a splat:
set(:auth) do |*roles| # <- notice the splat here condition do unless logged_in? && roles.any? {|role| current_user.in_role? role } redirect "/login/", 303 end end end get "/my/account/", :auth => [:user, :admin] do "Your Account Details" end get "/only/admin/", :auth => :admin do "Only admins are allowed here!" end
Return Values¶ ↑
The return value of a route block determines at least the response body passed on to the HTTP client, or at least the next middleware in the Rack
stack. Most commonly, this is a string, as in the above examples. But other values are also accepted.
You can return any object that would either be a valid Rack
response, Rack
body object or HTTP status code:
-
An Array with three elements:
[status (Integer), headers (Hash), response body (responds to #each)]
-
An Array with two elements:
[status (Integer), response body (responds to #each)]
-
An object that responds to
#each
and passes nothing but strings to the given block -
A Integer representing the status code
That way we can, for instance, easily implement a streaming example:
class Stream def each 100.times { |i| yield "#{i}\n" } end end get('/') { Stream.new }
You can also use the stream
helper method (described below) to reduce boiler plate and embed the streaming logic in the route.
Custom Route Matchers¶ ↑
As shown above, Sinatra
ships with built-in support for using String patterns and regular expressions as route matches. However, it does not stop there. You can easily define your own matchers:
class AllButPattern Match = Struct.new(:captures) def initialize(except) @except = except @captures = Match.new([]) end def match(str) @captures unless @except === str end end def all_but(pattern) AllButPattern.new(pattern) end get all_but("/index") do # ... end
Note that the above example might be over-engineered, as it can also be expressed as:
get // do pass if request.path_info == "/index" # ... end
Or, using negative look ahead:
get %r{(?!/index)} do # ... end
Static Files¶ ↑
Static files are served from the ./public
directory. You can specify a different location by setting the :public_folder
option:
set :public_folder, __dir__ + '/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.
Views / Templates¶ ↑
Each template language is exposed via its own rendering method. These methods simply return a string:
get '/' do erb :index end
This renders 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.
Literal Templates¶ ↑
get '/' do haml '%div.title Hello World' end
Renders the template string. You can optionally specify :path
and :line
for a clearer backtrace if there is a filesystem path or line associated with that string:
get '/' do haml '%div.title Hello World', :path => 'examples/file.haml', :line => 3 end
Available Template Languages¶ ↑
Some languages have multiple implementations. To specify what implementation to use (and to be thread-safe), you should simply require it first:
require 'rdiscount' # or require 'bluecloth' get('/') { markdown :index }
Haml Templates¶ ↑
Dependency | haml |
File Extension | .haml |
Example | haml :index, :format => :html5 |
Erb Templates¶ ↑
Dependency | erubi or erubis or erb (included in Ruby) |
File Extensions | .erb, .rhtml or .erubi (Erubi only) or .erubis (Erubis only) |
Example | erb :index |
Builder Templates¶ ↑
Dependency | builder |
File Extension | .builder |
Example | builder { |xml| xml.em "hi" } |
It also takes a block for inline templates (see example).
Nokogiri Templates¶ ↑
Dependency | nokogiri |
File Extension | .nokogiri |
Example | nokogiri { |xml| xml.em "hi" } |
It also takes a block for inline templates (see example).
Sass Templates¶ ↑
Dependency | sass |
File Extension | .sass |
Example | sass :stylesheet, :style => :expanded |
SCSS Templates¶ ↑
Dependency | sass |
File Extension | .scss |
Example | scss :stylesheet, :style => :expanded |
Less Templates¶ ↑
Dependency | less |
File Extension | .less |
Example | less :stylesheet |
Liquid Templates¶ ↑
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.
Markdown Templates¶ ↑
Dependency | Anyone of: RDiscount, RedCarpet, BlueCloth, kramdown, maruku commonmarker pandoc |
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:
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.
Textile Templates¶ ↑
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:
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.
RDoc Templates¶ ↑
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:
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.
AsciiDoc Templates¶ ↑
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.
Radius Templates¶ ↑
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.
Markaby Templates¶ ↑
Dependency | Markaby |
File Extension | .mab |
Example | markaby { h1 "Welcome!" } |
It also takes a block for inline templates (see example).
RABL Templates¶ ↑
Dependency | Rabl |
File Extension | .rabl |
Example | rabl :index |
Slim Templates¶ ↑
Dependency | Slim Lang |
File Extension | .slim |
Example | slim :index |
Creole Templates¶ ↑
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:
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.
MediaWiki Templates¶ ↑
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:
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.
CoffeeScript Templates¶ ↑
Dependency | CoffeeScript and a way to execute javascript |
File Extension | .coffee |
Example | coffee :index |
Stylus Templates¶ ↑
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
Yajl Templates¶ ↑
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);
WLang Templates¶ ↑
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.
Accessing Variables in Templates¶ ↑
Templates are evaluated within the same context as route handlers. Instance variables set in route handlers are directly accessible by templates:
get '/:id' do @foo = Foo.find(params['id']) haml '%h1= @foo.name' end
Or, specify an explicit Hash of local variables:
get '/:id' do foo = Foo.find(params['id']) haml '%h1= bar.name', :locals => { :bar => foo } end
This is typically used when rendering templates as partials from within other templates.
Templates with yield
and nested layouts¶ ↑
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.
Inline 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.
Named Templates¶ ↑
Templates may also be defined using the top-level template
method:
template :layout do "%html\n =yield\n" end template :index do '%div.title Hello World!' end get '/' do haml :index end
If a template named “layout” exists, it will be used each time a template is rendered. You can 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
Associating File Extensions¶ ↑
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]
Adding Your Own Template Engine¶ ↑
First, register your engine with Tilt, then create a rendering method:
Tilt.register :myat, MyAwesomeTemplateEngine helpers do def myat(*args) render(:myat, *args) end end get '/' do myat :index end
Renders ./views/index.myat
. Learn more about Tilt.
Using Custom Logic for Template Lookup¶ ↑
To implement your own template lookup mechanism you can write your own #find_template
method:
configure do set :views, [ './views/a', './views/b' ] end def find_template(views, name, engine, &block) Array(views).each do |v| super(v, name, engine, &block) end end
Filters¶ ↑
Before filters are evaluated before each request within the same context as the routes will be and can modify the request and response. Instance variables set in filters are accessible by routes and templates:
before do @note = 'Hi!' request.path_info = '/foo/bar/baz' end get '/foo/*' do @note #=> 'Hi!' params['splat'] #=> 'bar/baz' end
After filters are evaluated after each request within the same context 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
Helpers¶ ↑
Use the top-level helpers
method to define helper methods for use in route handlers and templates:
helpers do def bar(name) "#{name}bar" end end get '/:name' do bar(params['name']) end
Alternatively, helper methods can be separately defined in a module:
module FooUtils def foo(name) "#{name}foo" end end module BarUtils def bar(name) "#{name}bar" end end helpers FooUtils, BarUtils
The effect is the same as including the modules in the application class.
Using Sessions¶ ↑
A session is used to keep state during requests. If activated, you have one session hash per user session:
enable :sessions get '/' do "value = " << session[:value].inspect end get '/:value' do session['value'] = params['value'] end
Session Secret Security¶ ↑
To improve security, the session data in the cookie is signed with a session secret using HMAC-SHA1
. This session secret should optimally be a cryptographically secure random value of an appropriate length which for HMAC-SHA1
is greater than or equal to 64 bytes (512 bits, 128 hex characters). You would be advised not to use a secret that is less than 32 bytes of randomness (256 bits, 64 hex characters). It is therefore very important that you don’t just make the secret up, but instead use a secure random number generator to create it. Humans are extremely bad at generating random values.
By default, a 32 byte secure random session secret is generated for you by Sinatra
, but it will change with every restart of your application. If you have multiple instances of your application, and you let Sinatra
generate the key, each instance would then have a different session key which is probably not what you want.
For better security and usability it’s recommended that you generate a secure random secret and store it in an environment variable on each host running your application so that all of your application instances will share the same secret. You should periodically rotate this session secret to a new value. Here are some examples of how you might create a 64 byte secret and set it:
Session Secret Generation
$ ruby -e "require 'securerandom'; puts SecureRandom.hex(64)" 99ae8af...snip...ec0f262ac
Session Secret Generation (Bonus Points)
Use the sysrandom gem to prefer use of system RNG facilities to generate random values instead of userspace OpenSSL
which MRI Ruby currently defaults to:
$ gem install sysrandom Building native extensions. This could take a while... Successfully installed sysrandom-1.x 1 gem installed $ ruby -e "require 'sysrandom/securerandom'; puts SecureRandom.hex(64)" 99ae8af...snip...ec0f262ac
Session Secret Environment Variable
Set a SESSION_SECRET
environment variable for Sinatra
to the value you generated. Make this value persistent across reboots of your host. Since the method for doing this will vary across systems this is for illustrative purposes only:
# echo "export SESSION_SECRET=99ae8af...snip...ec0f262ac" >> ~/.bashrc
Session Secret App Config
Setup your app config to fail-safe to a secure random secret if the SESSION_SECRET
environment variable is not available.
For bonus points use the sysrandom gem here as well:
require 'securerandom' # -or- require 'sysrandom/securerandom' set :session_secret, ENV.fetch('SESSION_SECRET') { SecureRandom.hex(64) }
Session Config¶ ↑
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'
Choosing Your Own Session Middleware¶ ↑
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, one of the following methods can be used:
enable :sessions set :session_store, Rack::Session::Pool
Or to set up sessions with a hash of options:
set :sessions, :expire_after => 2592000 set :session_store, Rack::Session::Pool
Another option is to not call enable :sessions
, but instead pull in your middleware of choice as you would any other middleware.
It is important to note that when using this method, session based protection will not be enabled by default.
The Rack
middleware to do that will also need to be added:
use Rack::Session::Pool, :expire_after => 2592000 use Rack::Protection::RemoteToken use Rack::Protection::SessionHijacking
See ‘Configuring attack protection’ for more information.
Halting¶ ↑
To immediately stop a request within a filter or route use:
halt
You can also specify the status when halting:
halt 410
Or the body:
halt 'this will be the body'
Or both:
halt 401, 'go away!'
With headers:
halt 402, {'Content-Type' => 'text/plain'}, 'revenge'
It is of course possible to combine a template with halt
:
halt erb(:error)
Passing¶ ↑
A route can punt processing to the next matching route using 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.
Triggering Another Route¶ ↑
Sometimes pass
is not what you want, instead you would like to get the result of calling another route. Simply use call
to achieve this:
get '/foo' do status, headers, body = call env.merge("PATH_INFO" => '/bar') [status, headers, body.map(&:upcase)] end get '/bar' do "bar" end
Note that in the example above, you would ease testing and increase performance by simply moving "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
.
Setting Body, Status Code and Headers¶ ↑
It is possible and recommended to set the status code and response body with the return value of the route block. However, in some scenarios you might want to set the body at an arbitrary point in the execution flow. You can do so with the body
helper method. If you do so, you can use that method from there on to access the body:
get '/foo' do body "bar" end after do puts body end
It is also possible to pass a block to body
, which will be executed by the Rack
handler (this can be used to implement streaming, see “Return Values”).
Similar to the body, you can also set the status code and headers:
get '/foo' do status 418 headers \ "Allow" => "BREW, POST, GET, PROPFIND, WHEN", "Refresh" => "Refresh: 20; https://ietf.org/rfc/rfc2324.txt" body "I'm a tea pot!" end
Like body
, headers
and status
with no arguments can be used to access their current values.
Streaming Responses¶ ↑
Sometimes you want to start sending out data while still generating parts of the response body. In extreme examples, you want to keep sending data until the client closes the connection. You can use the stream
helper to avoid creating your own wrapper:
get '/' do stream do |out| out << "It's gonna be legen -\n" sleep 0.5 out << " (wait for it) \n" sleep 1 out << "- dary!\n" end end
This allows you to implement streaming APIs, Server Sent Events, 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 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 Rainbows. Other servers will still close the stream:
# config.ru require 'sinatra/base' class App < Sinatra::Base connections = [] get '/subscribe', provides: 'text/event-stream' do # register a client's interest in server events stream(:keep_open) do |out| connections << out # purge dead connections connections.reject!(&:closed?) end end post '/' do connections.each do |out| # notify client that a new message has arrived out << "data: #{params[:msg]}\n\n" # indicate client to connect again out.close end 204 # response without entity body end end run App
# rainbows.conf Rainbows! do use :EventMachine end ```` Run:
shell rainbows -c rainbows.conf
It's also possible for the client to close the connection when trying to write to the socket. Because of this, it's recommended to check `out.closed?` before trying to write. ### Logging In the request scope, the `logger` helper exposes a `Logger` instance:
ruby 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:
ruby 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']`. ### Mime Types When using `send_file` or static files you may have mime types Sinatra doesn't understand. Use `mime_type` to register them by file extension:
ruby configure do mime_type :foo, ‘text/foo’ end
You can also use it with the `content_type` helper:
ruby get ‘/’ do content_type :foo “foo foo foo” end
### Generating URLs For generating URLs you should use the `url` helper method, for instance, in Haml:
ruby %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](#browser-redirect) for an example). ### Browser Redirect You can trigger a browser redirect with the `redirect` helper method:
ruby get ‘/foo’ do redirect to(‘/bar’) end
Any additional parameters are handled like arguments passed to `halt`:
ruby redirect to(‘/bar’), 303 redirect ‘www.google.com/’, ‘wrong place, buddy’
You can also easily redirect back to the page the user came from with `redirect back`:
ruby 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:
ruby redirect to(‘/bar?sum=42’)
Or use a session:
ruby enable :sessions
get ‘/foo’ do session = ‘foo’ redirect to(‘/bar’) end
get ‘/bar’ do session end
### Cache Control Setting your headers correctly is the foundation for proper HTTP caching. You can easily set the Cache-Control header like this:
ruby get ‘/’ do cache_control :public “cache it!” end
Pro tip: Set up caching in a before filter:
ruby 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:
ruby 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:
ruby get “/article/:id” do @article = Article.find params last_modified @article.updated_at etag @article.sha1 erb :article end
It is also possible to use a [weak ETag](https://en.wikipedia.org/wiki/HTTP_ETag#Strong_and_weak_validation):
ruby 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](https://github.com/rtomayko/rack-cache#readme):
ruby 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](#cache-control)) 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:
ruby 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:
ruby etag ”, :new_resource => true, :kind => :weak
### Sending Files To return the contents of a file as the response, you can use the `send_file` helper method:
ruby get ‘/’ do send_file ‘foo.png’ end
It also takes options:
ruby send_file ‘foo.png’, :type => :jpg
The options are: <dl> <dt>filename</dt> <dd>File name to be used in the response, defaults to the real file name.</dd> <dt>last_modified</dt> <dd>Value for Last-Modified header, defaults to the file's mtime.</dd> <dt>type</dt> <dd>Value for Content-Type header, guessed from the file extension if missing.</dd> <dt>disposition</dt> <dd> Value for Content-Disposition header, possible values: <tt>nil</tt> (default), <tt>:attachment</tt> and <tt>:inline</tt> </dd> <dt>length</dt> <dd>Value for Content-Length header, defaults to file size.</dd> <dt>status</dt> <dd> 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> </dl> ### Accessing the Request Object The incoming request object can be accessed from request level (filter, routes, error handlers) through the `request` method:
ruby
app running on 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 # 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 # “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:
ruby before { request.path_info = “/” }
get “/” do “all requests end up here” end
The `request.body` is an IO or StringIO object:
ruby post “/api” do request.body.rewind # in case someone already read it data = JSON.parse request.body.read “Hello #{data}!” end
### Attachments You can use the `attachment` helper to tell the browser the response should be stored on disk rather than displayed in the browser:
ruby get ‘/’ do attachment “store it!” end
You can also pass it a file name:
ruby get ‘/’ do attachment “info.txt” “store it!” end
### Dealing with Date and Time Sinatra offers a `time_for` helper method that generates a Time object from the given value. It is also able to convert `DateTime`, `Date` and similar classes:
ruby get ‘/’ do pass if Time.now > time_for(‘Dec 23, 2016’) “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:
ruby helpers do def time_for(value) case value when :yesterday then Time.now - 24_60_60 when :tomorrow then Time.now + 24_60_60 else super end end end
get ‘/’ do last_modified :yesterday expires :tomorrow “hello” end
### Looking Up Template Files The `find_template` helper is used to find template files for rendering:
ruby find_template settings.views, ‘foo’, Tilt 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:
ruby 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:
ruby 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 } folder ||= views 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. ## Configuration Run once, at startup, in any environment:
ruby 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 (`APP_ENV` environment variable) is set to `:production`:
ruby configure :production do … end
Run when the environment is set to either `:production` or `:test`:
ruby configure :production, :test do … end
You can access those options via `settings`:
ruby configure do set :foo, ‘bar’ end
get ‘/’ do settings.foo? # => true settings.foo # => ‘bar’ … end
### Configuring attack protection Sinatra is using [Rack::Protection](https://github.com/sinatra/sinatra/tree/master/rack-protection#readme) to defend your application against common, opportunistic attacks. You can easily disable this behavior (which will open up your application to tons of common vulnerabilities):
ruby disable :protection
To skip a single defense layer, set `protection` to an options hash:
ruby set :protection, :except => :path_traversal
You can also hand in an array in order to disable a list of protections:
ruby set :protection, :except => [:path_traversal, :session_hijacking]
By default, Sinatra will only set up session based protection if `:sessions` have been enabled. See '[Using Sessions](#using-sessions)'. Sometimes you may want to set up sessions "outside" of the Sinatra app, such as in the config.ru or with a separate `Rack::Builder` instance. In that case you can still set up session based protection by passing the `:session` option:
ruby set :protection, :session => true
### Available Settings <dl> <dt>absolute_redirects</dt> <dd> If disabled, Sinatra will allow relative redirects, however, Sinatra will no longer conform with RFC 2616 (HTTP 1.1), which only allows absolute redirects. </dd> <dd> Enable if your app is running behind a reverse proxy that has not been set up properly. Note that the <tt>url</tt> helper will still produce absolute URLs, unless you pass in <tt>false</tt> as the second parameter. </dd> <dd>Disabled by default.</dd> <dt>add_charset</dt> <dd> Mime types the <tt>content_type</tt> helper will automatically add the charset info to. You should add to it rather than overriding this option: <tt>settings.add_charset << "application/foobar"</tt> </dd> <dt>app_file</dt> <dd> Path to the main application file, used to detect project root, views and public folder and inline templates. </dd> <dt>bind</dt> <dd> IP address to bind to (default: <tt>0.0.0.0</tt> <em>or</em> <tt>localhost</tt> if your `environment` is set to development). Only used for built-in server. </dd> <dt>default_content_type</dt> <dd> Content-Type to assume if unknown (defaults to <tt>"text/html"</tt>). Set to <tt>nil</tt> to not set a default Content-Type on every response; when configured so, you must set the Content-Type manually when emitting content or the user-agent will have to sniff it (or, if <tt>nosniff</tt> is enabled in Rack::Protection::XSSHeader, assume <tt>application/octet-stream</tt>). </dd> <dt>default_encoding</dt> <dd>Encoding to assume if unknown (defaults to <tt>"utf-8"</tt>).</dd> <dt>dump_errors</dt> <dd>Display errors in the log.</dd> <dt>environment</dt> <dd> Current environment. Defaults to <tt>ENV['APP_ENV']</tt>, or <tt>"development"</tt> if not available. </dd> <dt>logging</dt> <dd>Use the logger.</dd> <dt>lock</dt> <dd> Places a lock around every request, only running processing on request per Ruby process concurrently. </dd> <dd>Enabled if your app is not thread-safe. Disabled by default.</dd> <dt>method_override</dt> <dd> Use <tt>_method</tt> magic to allow put/delete forms in browsers that don't support it. </dd> <dt>mustermann_opts</dt> <dd> A default hash of options to pass to Mustermann.new when compiling routing paths. </dd> <dt>port</dt> <dd>Port to listen on. Only used for built-in server.</dd> <dt>prefixed_redirects</dt> <dd> Whether or not to insert <tt>request.script_name</tt> into redirects if no absolute path is given. That way <tt>redirect '/foo'</tt> would behave like <tt>redirect to('/foo')</tt>. Disabled by default. </dd> <dt>protection</dt> <dd> Whether or not to enable web attack protections. See protection section above. </dd> <dt>public_dir</dt> <dd>Alias for <tt>public_folder</tt>. See below.</dd> <dt>public_folder</dt> <dd> Path to the folder public files are served from. Only used if static file serving is enabled (see <tt>static</tt> setting below). Inferred from <tt>app_file</tt> setting if not set. </dd> <dt>quiet</dt> <dd> Disables logs generated by Sinatra's start and stop commands. <tt>false</tt> by default. </dd> <dt>reload_templates</dt> <dd> Whether or not to reload templates between requests. Enabled in development mode. </dd> <dt>root</dt> <dd> Path to project root folder. Inferred from <tt>app_file</tt> setting if not set. </dd> <dt>raise_errors</dt> <dd> Raise exceptions (will stop application). Enabled by default when <tt>environment</tt> is set to <tt>"test"</tt>, disabled otherwise. </dd> <dt>run</dt> <dd> If enabled, Sinatra will handle starting the web server. Do not enable if using rackup or other means. </dd> <dt>running</dt> <dd>Is the built-in server running now? Do not change this setting!</dd> <dt>server</dt> <dd> Server or list of servers to use for built-in server. Order indicates priority, default depends on Ruby implementation. </dd> <dt>server_settings</dt> <dd> If you are using a WEBrick web server, presumably for your development environment, you can pass a hash of options to <tt>server_settings</tt>, such as <tt>SSLEnable</tt> or <tt>SSLVerifyClient</tt>. However, web servers such as Puma do not support this, so you can set <tt>server_settings</tt> by defining it as a method when you call <tt>configure</tt>. </dd> <dt>sessions</dt> <dd> Enable cookie-based sessions support using <tt>Rack::Session::Cookie</tt>. See 'Using Sessions' section for more information. </dd> <dt>session_store</dt> <dd> The Rack session middleware used. Defaults to <tt>Rack::Session::Cookie</tt>. See 'Using Sessions' section for more information. </dd> <dt>show_exceptions</dt> <dd> Show a stack trace in the browser when an exception happens. Enabled by default when <tt>environment</tt> is set to <tt>"development"</tt>, disabled otherwise. </dd> <dd> Can also be set to <tt>:after_handler</tt> to trigger app-specified error handling before showing a stack trace in the browser. </dd> <dt>static</dt> <dd>Whether Sinatra should handle serving static files.</dd> <dd>Disable when using a server able to do this on its own.</dd> <dd>Disabling will boost performance.</dd> <dd> Enabled by default in classic style, disabled for modular apps. </dd> <dt>static_cache_control</dt> <dd> When Sinatra is serving static files, set this to add <tt>Cache-Control</tt> headers to the responses. Uses the <tt>cache_control</tt> helper. Disabled by default. </dd> <dd> Use an explicit array when setting multiple values: <tt>set :static_cache_control, [:public, :max_age => 300]</tt> </dd> <dt>threaded</dt> <dd> If set to <tt>true</tt>, will tell server to use <tt>EventMachine.defer</tt> for processing the request. </dd> <dt>traps</dt> <dd>Whether Sinatra should handle system signals.</dd> <dt>views</dt> <dd> Path to the views folder. Inferred from <tt>app_file</tt> setting if not set. </dd> <dt>x_cascade</dt> <dd> Whether or not to set the X-Cascade header if no route matches. Defaults to <tt>true</tt>. </dd> </dl> ## Environments There are three predefined `environments`: `"development"`, `"production"` and `"test"`. Environments can be set through the `APP_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 `APP_ENV` environment variable:
shell APP_ENV=production ruby my_app.rb
You can use predefined methods: `development?`, `test?` and `production?` to check the current environment setting:
ruby get ‘/’ do if settings.development? “development!” else “not development!” end end
## Error Handling Error handlers run within the same context as routes and before filters, which means you get all the goodies it has to offer, like `haml`, `erb`, `halt`, etc. ### Not Found When a `Sinatra::NotFound` exception is raised, or the response's status code is 404, the `not_found` handler is invoked:
ruby 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. But note in development it will only run if you set the show exceptions option to `:after_handler`:
ruby set :show_exceptions, :after_handler
The exception object can be obtained from the `sinatra.error` Rack variable:
ruby error do ‘Sorry there was a nasty error - ’ + env.message end
Custom errors:
ruby error MyCustomError do ‘So what happened was…’ + env.message end
Then, if this happens:
ruby 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:
ruby error 403 do ‘Access forbidden’ end
get ‘/secret’ do 403 end
Or a range:
ruby 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. ## Rack Middleware Sinatra rides on [Rack](https://rack.github.io/), 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:
ruby 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://www.rubydoc.info/github/rack/rack/master/Rack/Builder) DSL (most frequently used from rackup files). For example, the `use` method accepts multiple/variable args as well as blocks:
ruby use Rack::Auth::Basic do |username, password| username == ‘admin’ && password == ‘secret’ end
Rack is distributed with a variety of standard middleware for logging, debugging, URL routing, authentication, and session handling. Sinatra uses many of these components automatically based on configuration so you typically don't have to `use` them explicitly. You can find useful middleware in [rack](https://github.com/rack/rack/tree/master/lib/rack), [rack-contrib](https://github.com/rack/rack-contrib#readme), or in the [Rack wiki](https://github.com/rack/rack/wiki/List-of-Middleware). ## Testing Sinatra tests can be written using any Rack-based testing library or framework. [Rack::Test](http://www.rubydoc.info/github/brynary/rack-test/master/frames) is recommended:
ruby require ‘my_sinatra_app’ require ‘minitest/autorun’ require ‘rack/test’
class MyAppTest < Minitest::Test 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_user_agent 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. ## Sinatra::Base - Middleware, Libraries, and Modular Apps Defining your app at the top-level works well for micro-apps but has considerable drawbacks when building reusable components such as Rack middleware, Rails metal, simple libraries with a server component, or even Sinatra extensions. The top-level assumes a micro-app style configuration (e.g., a single application file, `./public` and `./views` directories, logging, exception detail page, etc.). That's where `Sinatra::Base` comes into play:
ruby 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 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 [Configuring Settings](http://www.sinatrarb.com/configuration.html) for details on available options and their behavior. If you want behavior more similar to when you define your app at the top level (also known as Classic style), you can subclass `Sinatra::Application`:
ruby require ‘sinatra/base’
class MyApp < Sinatra::Application
get ‘/’ do ‘Hello world!’ end end
### Modular vs. Classic Style Contrary to common belief, there is nothing wrong with the classic style. If it suits your application, you do not have to switch to a modular application. The main disadvantage of using the classic style rather than the modular style is that you will only have one Sinatra application per Ruby process. If you plan to use more than one, switch to the modular style. There is no reason you cannot mix the modular and the classic styles. If switching from one style to the other, you should be aware of slightly different default settings: <table> <tr> <th>Setting</th> <th>Classic</th> <th>Modular</th> <th>Modular</th> </tr> <tr> <td>app_file</td> <td>file loading sinatra</td> <td>file subclassing Sinatra::Base</td> <td>file subclassing Sinatra::Application</td> </tr> <tr> <td>run</td> <td>$0 == app_file</td> <td>false</td> <td>false</td> </tr> <tr> <td>logging</td> <td>true</td> <td>false</td> <td>true</td> </tr> <tr> <td>method_override</td> <td>true</td> <td>false</td> <td>true</td> </tr> <tr> <td>inline_templates</td> <td>true</td> <td>false</td> <td>true</td> </tr> <tr> <td>static</td> <td>true</td> <td>File.exist?(public_folder)</td> <td>true</td> </tr> </table> ### Serving a Modular Application There are two common options for starting a modular app, actively starting with `run!`:
ruby
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:
shell ruby my_app.rb
Or with a `config.ru` file, which allows using any Rack handler:
ruby
config.ru (run with rackup)¶ ↑
require ‘./my_app’ run MyApp
Run:
shell rackup -p 4567
### Using a Classic Style Application with a config.ru Write your app file:
ruby
app.rb¶ ↑
require ‘sinatra’
get ‘/’ do ‘Hello world!’ end
And a corresponding `config.ru`:
ruby require ‘./app’ run Sinatra::Application
### When to use a config.ru? 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`.** ### Using Sinatra as Middleware Not only is Sinatra able to use other Rack middleware, any Sinatra application can in turn be added in front of any Rack endpoint as middleware itself. This endpoint could be another Sinatra application, or any other Rack-based application (Rails/Hanami/Roda/...):
ruby require ‘sinatra/base’
class LoginScreen < Sinatra::Base enable :sessions
get(‘/login’) { haml :login }
post(‘/login’) do if params == ‘admin’ && params == ‘admin’ session = params else redirect ‘/login’ end end end
class MyApp < Sinatra::Base # middleware will run before filters use LoginScreen
before do unless session halt “Access denied, please <a href=‘/login’>login</a>.” end end
get(‘/’) { “Hello #{session}.” } end
### Dynamic Application Creation Sometimes you want to create new applications at runtime without having to assign them to a constant. You can do this with `Sinatra.new`:
ruby require ‘sinatra/base’ my_app = Sinatra.new { get(‘/’) { “hi” } } my_app.run!
It takes the application to inherit from as an optional argument:
ruby
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:
ruby require ‘sinatra/base’
use Sinatra
do get(‘/’) { … } end
run RailsProject::Application
## Scopes and Binding The scope you are currently in determines what methods and variables are available. ### Application/Class Scope Every Sinatra application corresponds to a subclass of `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:
ruby 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 ### Request/Instance Scope For every incoming request, a new instance of your application class is created, and all handler blocks run in that scope. From within this scope you can access the `request` and `session` objects or call rendering methods like `erb` or `haml`. You can access the application scope from within the request scope via the `settings` helper:
ruby 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 ### Delegation Scope The delegation scope just forwards methods to the class scope. However, it does not behave exactly like the class scope, as you do not have the class binding. Only methods explicitly marked for delegation are available, and you do not share variables/state with the class scope (read: you have a different `self`). You can explicitly add method delegations by calling `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](https://github.com/sinatra/sinatra/blob/ca06364/lib/sinatra/base.rb#L1609-1633) being [extending the main object](https://github.com/sinatra/sinatra/blob/ca06364/lib/sinatra/main.rb#L28-30). ## Command Line Sinatra applications can be run directly:
shell ruby myapp.rb [-h] [-x] [-q] [-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 puma) -q # turn on quiet mode for server (default is off) -x # turn on the mutex lock (default is off)
### Multi-threading _Paraphrasing from [this StackOverflow answer](https://stackoverflow.com/a/6282999/5245129) by Konstantin_ Sinatra doesn't impose any concurrency model, but leaves that to the underlying Rack handler (server) like Puma or WEBrick. Sinatra itself is thread-safe, so there won't be any problem if the Rack handler uses a threaded model of concurrency. This would mean that when starting the server, you'd have to specify the correct invocation method for the specific Rack handler. The following example is a demonstration of how to start a multi-threaded Rainbows server:
ruby
config.ru¶ ↑
require ‘sinatra/base’
class App < Sinatra::Base get ‘/’ do “Hello, World” end end
run App
ruby
rainbows.conf¶ ↑
Rainbows configurator is based on Unicorn.¶ ↑
Rainbows! do use :ThreadSpawn end
To start the server, the command would be:
shell rainbows -c rainbows.conf
## Requirement The following Ruby versions are officially supported: <dl> <dt>Ruby 2.3</dt> <dd> 2.3 is fully supported and recommended. There are currently no plans to drop official support for it. </dd> <dt>Rubinius</dt> <dd> Rubinius is officially supported (Rubinius >= 2.x). It is recommended to <tt>gem install puma</tt>. </dd> <dt>JRuby</dt> <dd> The latest stable release of JRuby is officially supported. It is not recommended to use C extensions with JRuby. It is recommended to <tt>gem install trinidad</tt>. </dd> </dl> Versions of Ruby prior to 2.3 are no longer supported as of Sinatra 2.1.0. 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 (future releases of MRI), but we can't guarantee anything, since it is constantly moving. Expect upcoming 2.x releases 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 2.2. ## The Bleeding Edge If you would like to use Sinatra's latest bleeding-edge code, feel free to run your application against the master branch, it should be rather stable. We also push out prerelease gems from time to time, so you can do a
shell gem install sinatra –pre
to get some of the latest features. ### With Bundler If you want to run your application with the latest Sinatra, using [Bundler](https://bundler.io) is the recommended way. First, install bundler, if you haven't:
shell gem install bundler
Then, in your project directory, create a `Gemfile`:
ruby source ‘rubygems.org’ gem ‘sinatra’, :github => ‘sinatra/sinatra’
other dependencies¶ ↑
gem ‘haml’ # for instance, if you use haml
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:
shell bundle exec ruby myapp.rb
“‘
Versioning¶ ↑
Sinatra
follows Semantic Versioning, both SemVer and SemVerTag.
Further Reading¶ ↑
-
Project Website - Additional documentation, news, and links to other resources.
-
Contributing - Find a bug? Need help? Have a patch?
-
Sinatra & Friends on Slack (get an invite)
-
Sinatra Book - Cookbook Tutorial
-
Sinatra Recipes - Community contributed recipes
-
API documentation for the latest release or the current HEAD on RubyDoc