module ActionDispatch
module Routing
# In <tt>config/routes.rb</tt> you define URL-to-controller mappings, but the reverse
# is also possible: an URL can be generated from one of your routing definitions.
# URL generation functionality is centralized in this module.
#
# See ActionDispatch::Routing for general information about routing and routes.rb.
#
# <b>Tip:</b> If you need to generate URLs from your models or some other place,
# then ActionController::UrlFor is what you're looking for. Read on for
# an introduction.
#
# == URL generation from parameters
#
# As you may know, some functions, such as ActionController::Base#url_for
# and ActionView::Helpers::UrlHelper#link_to, can generate URLs given a set
# of parameters. For example, you've probably had the chance to write code
# like this in one of your views:
#
# <%= link_to('Click here', :controller => 'users',
# :action => 'new', :message => 'Welcome!') %>
# # => "/users/new?message=Welcome%21"
#
# link_to, and all other functions that require URL generation functionality,
# actually use ActionController::UrlFor under the hood. And in particular,
# they use the ActionController::UrlFor#url_for method. One can generate
# the same path as the above example by using the following code:
#
# include UrlFor
# url_for(:controller => 'users',
# :action => 'new',
# :message => 'Welcome!',
# :only_path => true)
# # => "/users/new?message=Welcome%21"
#
# Notice the <tt>:only_path => true</tt> part. This is because UrlFor has no
# information about the website hostname that your Rails app is serving. So if you
# want to include the hostname as well, then you must also pass the <tt>:host</tt>
# argument:
#
# include UrlFor
# url_for(:controller => 'users',
# :action => 'new',
# :message => 'Welcome!',
# :host => 'www.example.com') # Changed this.
# # => "http://www.example.com/users/new?message=Welcome%21"
#
# By default, all controllers and views have access to a special version of url_for,
# that already knows what the current hostname is. So if you use url_for in your
# controllers or your views, then you don't need to explicitly pass the <tt>:host</tt>
# argument.
#
# For convenience reasons, mailers provide a shortcut for ActionController::UrlFor#url_for.
# So within mailers, you only have to type 'url_for' instead of 'ActionController::UrlFor#url_for'
# in full. However, mailers don't have hostname information, and what's why you'll still
# have to specify the <tt>:host</tt> argument when generating URLs in mailers.
#
#
# == URL generation for named routes
#
# UrlFor also allows one to access methods that have been auto-generated from
# named routes. For example, suppose that you have a 'users' resource in your
# <tt>config/routes.rb</tt>:
#
# resources :users
#
# This generates, among other things, the method <tt>users_path</tt>. By default,
# this method is accessible from your controllers, views and mailers. If you need
# to access this auto-generated method from other places (such as a model), then
# you can do that by including ActionController::UrlFor in your class:
#
# class User < ActiveRecord::Base
# include Rails.application.routes.url_helpers
#
# def base_uri
# user_path(self)
# end
# end
#
# User.find(1).base_uri # => "/users/1"
#
module UrlFor
extend ActiveSupport::Concern
include PolymorphicRoutes
included do
# TODO: with_routing extends @controller with url_helpers, trickling down to including this module which overrides its default_url_options
unless method_defined?(:default_url_options)
# Including in a class uses an inheritable hash. Modules get a plain hash.
if respond_to?(:class_attribute)
class_attribute :default_url_options
else
mattr_accessor :default_url_options
remove_method :default_url_options
end
self.default_url_options = {}
end
end
def initialize(*)
@_routes = nil
super
end
def url_options
default_url_options
end
# Generate a url based on the options provided, default_url_options and the
# routes defined in routes.rb. The following options are supported:
#
# * <tt>:only_path</tt> - If true, the relative url is returned. Defaults to +false+.
# * <tt>:protocol</tt> - The protocol to connect to. Defaults to 'http'.
# * <tt>:host</tt> - Specifies the host the link should be targeted at.
# If <tt>:only_path</tt> is false, this option must be
# provided either explicitly, or via +default_url_options+.
# * <tt>:subdomain</tt> - Specifies the subdomain of the link, using the +tld_length+
# to split the domain from the host.
# * <tt>:domain</tt> - Specifies the domain of the link, using the +tld_length+
# to split the subdomain from the host.
# * <tt>:tld_length</tt> - Number of labels the TLD id composed of, only used if
# <tt>:subdomain</tt> or <tt>:domain</tt> are supplied. Defaults to
# <tt>ActionDispatch::Http::URL.tld_length</tt>, which in turn defaults to 1.
# * <tt>:port</tt> - Optionally specify the port to connect to.
# * <tt>:anchor</tt> - An anchor name to be appended to the path.
# * <tt>:trailing_slash</tt> - If true, adds a trailing slash, as in "/archive/2009/"
#
# Any other key (<tt>:controller</tt>, <tt>:action</tt>, etc.) given to
# +url_for+ is forwarded to the Routes module.
#
# Examples:
#
# url_for :controller => 'tasks', :action => 'testing', :host => 'somehost.org', :port => '8080'
# # => 'http://somehost.org:8080/tasks/testing'
# url_for :controller => 'tasks', :action => 'testing', :host => 'somehost.org', :anchor => 'ok', :only_path => true
# # => '/tasks/testing#ok'
# url_for :controller => 'tasks', :action => 'testing', :trailing_slash => true
# # => 'http://somehost.org/tasks/testing/'
# url_for :controller => 'tasks', :action => 'testing', :host => 'somehost.org', :number => '33'
# # => 'http://somehost.org/tasks/testing?number=33'
def url_for(options = nil)
case options
when String
options
when nil, Hash
_routes.url_for((options || {}).reverse_merge(url_options).symbolize_keys)
else
polymorphic_url(options)
end
end
protected
def _with_routes(routes)
old_routes, @_routes = @_routes, routes
yield
ensure
@_routes = old_routes
end
def _routes_context
self
end
end
end
end
