:subdomain, :domain and :tld_length options can now be used in url_for, allowing for easy manipulation of the host during link generation.

Signed-off-by: José Valim <jose.valim@gmail.com>

actionpack/lib/action_controller/metal/url_for.rb

@@ -6,7 +6,8 @@ module ActionController
 
     def url_options
       @_url_options ||= super.reverse_merge(
-        :host => request.host_with_port,
+        :host => request.host,
+        :port => request.optional_port,
         :protocol => request.protocol,
         :_path_segments => request.symbolized_path_parameters
       ).freeze
@@ -20,5 +21,6 @@ module ActionController
         @_url_options
       end
     end
+
   end
 end

actionpack/lib/action_dispatch/http/url.rb

@@ -4,6 +4,27 @@ module ActionDispatch
       mattr_accessor :tld_length
       self.tld_length = 1
 
+      def self.extract_domain(host, tld_length = @@tld_length)
+        return nil unless named_host?(host)
+
+        host.split('.').last(1 + tld_length).join('.')
+      end
+
+      def self.extract_subdomains(host, tld_length = @@tld_length)
+        return [] unless named_host?(host)
+        parts = host.split('.')
+        parts[0..-(tld_length+2)]
+      end
+
+      def self.extract_subdomain(host, tld_length = @@tld_length)
+        extract_subdomains(host, tld_length).join('.')
+      end
+
+      def self.named_host?(host)
+        !(host.nil? || /\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/.match(host))
+      end
+
+
       # Returns the complete URL used for this request.
       def url
         protocol + host_with_port + fullpath
@@ -31,15 +52,18 @@ module ActionDispatch
       # Returns a \host:\port string for this request, such as "example.com" or
       # "example.com:8080".
       def host_with_port
-        "#{host}#{port_string}"
+        opt_port = optional_port ? ":#{optional_port}" : nil
+        "#{host}#{opt_port}"
       end
 
       # Returns the port number of this request as an integer.
       def port
-        if raw_host_with_port =~ /:(\d+)$/
-          $1.to_i
-        else
-          standard_port
+        @port ||= begin
+          if raw_host_with_port =~ /:(\d+)$/
+            $1.to_i
+          else
+            standard_port
+          end
         end
       end
 
@@ -56,10 +80,10 @@ module ActionDispatch
         port == standard_port
       end
 
-      # Returns a \port suffix like ":8080" if the \port number of this request
+      # Returns a \port suffix like "8080" if the \port number of this request
       # is not the default HTTP \port 80 or HTTPS \port 443.
-      def port_string
-        port == standard_port ? '' : ":#{port}"
+      def optional_port
+        standard_port? ? nil : port
       end
 
       def server_port
@@ -69,9 +93,7 @@ module ActionDispatch
       # Returns the \domain part of a \host, such as "rubyonrails.org" in "www.rubyonrails.org". You can specify
       # a different <tt>tld_length</tt>, such as 2 to catch rubyonrails.co.uk in "www.rubyonrails.co.uk".
       def domain(tld_length = @@tld_length)
-        return nil unless named_host?(host)
-
-        host.split('.').last(1 + tld_length).join('.')
+        ActionDispatch::Http::URL.extract_domain(host, tld_length)
       end
 
       # Returns all the \subdomains as an array, so <tt>["dev", "www"]</tt> would be
@@ -79,20 +101,17 @@ module ActionDispatch
       # such as 2 to catch <tt>["www"]</tt> instead of <tt>["www", "rubyonrails"]</tt>
       # in "www.rubyonrails.co.uk".
       def subdomains(tld_length = @@tld_length)
-        return [] unless named_host?(host)
-        parts = host.split('.')
-        parts[0..-(tld_length+2)]
+        ActionDispatch::Http::URL.extract_subdomains(host, tld_length)
       end
 
+      # Returns all the \subdomains as a string, so <tt>"dev.www"</tt> would be
+      # returned for "dev.www.rubyonrails.org". You can specify a different <tt>tld_length</tt>,
+      # such as 2 to catch <tt>["www"]</tt> instead of <tt>"www.rubyonrails"</tt>
+      # in "www.rubyonrails.co.uk".
       def subdomain(tld_length = @@tld_length)
-        subdomains(tld_length).join('.')
+        subdomains(tld_length)
       end
 
-    private
-
-      def named_host?(host)
-        !(host.nil? || /\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/.match(host))
-      end
     end
   end
 end

actionpack/lib/action_dispatch/routing/route_set.rb

@@ -485,7 +485,8 @@ module ActionDispatch
         Generator.new(options, recall, self, extras).generate
       end
 
-      RESERVED_OPTIONS = [:anchor, :params, :only_path, :host, :protocol, :port, :trailing_slash, :script_name]
+      RESERVED_OPTIONS = [:host, :protocol, :port, :subdomain, :domain, :tld_length,
+                          :trailing_slash, :script_name, :anchor, :params, :only_path ]
 
       def _generate_prefix(options = {})
         nil
@@ -504,11 +505,8 @@ module ActionDispatch
           rewritten_url << (options[:protocol] || "http")
           rewritten_url << "://" unless rewritten_url.match("://")
           rewritten_url << rewrite_authentication(options)
-
-          raise "Missing host to link to! Please provide :host parameter or set default_url_options[:host]" unless options[:host]
-
-          rewritten_url << options[:host]
-          rewritten_url << ":#{options.delete(:port)}" if options.key?(:port)
+          rewritten_url << host_from_options(options)
+          rewritten_url << ":#{options.delete(:port)}" if options[:port]
         end
 
         script_name = options.delete(:script_name)
@@ -562,6 +560,34 @@ module ActionDispatch
       end
 
       private
+
+        def host_from_options(options)
+          computed_host = subdomain_and_domain(options) || options[:host]
+          unless computed_host
+            raise ArgumentError, "Missing host to link to! Please provide :host parameter or set default_url_options[:host]"
+          end
+          computed_host
+        end
+
+        def subdomain_and_domain(options)
+          tld_length = options[:tld_length] || ActionDispatch::Http::URL.tld_length
+
+          current_domain    = ActionDispatch::Http::URL.extract_domain(options[:host], tld_length)
+          current_subdomain = ActionDispatch::Http::URL.extract_subdomain(options[:host], tld_length)
+
+          domain_parts = if options[:subdomain] && options[:domain]
+            [options[:subdomain], options[:domain]]
+          elsif options[:subdomain]
+            [options[:subdomain], current_domain]
+          elsif options[:domain]
+            [current_subdomain, options[:domain]]
+          else
+            nil
+          end
+
+          domain_parts ? domain_parts.join('.') : nil
+        end
+
         def handle_positional_args(options)
           return unless args = options.delete(:_positional_args)
 

actionpack/lib/action_dispatch/routing/url_for.rb

@@ -115,6 +115,12 @@ module ActionDispatch
       # * <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> - Optionally specify the tld length (only used if :subdomain
+      #   or :domain are supplied).
       # * <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/"

actionpack/test/controller/url_for_test.rb

@@ -17,7 +17,7 @@ module AbstractController
       end
 
       def test_exception_is_thrown_without_host
-        assert_raise RuntimeError do
+        assert_raise ArgumentError do
           W.new.url_for :controller => 'c', :action => 'a', :id => 'i'
         end
       end
@@ -60,6 +60,27 @@ module AbstractController
         )
       end
 
+      def test_subdomain_may_be_changed
+        add_host!
+        assert_equal('http://api.basecamphq.com/c/a/i',
+          W.new.url_for(:subdomain => 'api', :controller => 'c', :action => 'a', :id => 'i')
+        )
+      end
+
+      def test_domain_may_be_changed
+        add_host!
+        assert_equal('http://www.37signals.com/c/a/i',
+          W.new.url_for(:domain => '37signals.com', :controller => 'c', :action => 'a', :id => 'i')
+        )
+      end
+
+      def test_tld_length_may_be_changed
+        add_host!
+        assert_equal('http://mobile.www.basecamphq.com/c/a/i',
+          W.new.url_for(:subdomain => 'mobile', :tld_length => 2, :controller => 'c', :action => 'a', :id => 'i')
+        )
+      end
+
       def test_port
         add_host!
         assert_equal('http://www.basecamphq.com:3000/c/a/i',

actionpack/test/dispatch/request_test.rb

@@ -164,12 +164,12 @@ class RequestTest < ActiveSupport::TestCase
     assert !request.standard_port?
   end
 
-  test "port string" do
+  test "optional port" do
     request = stub_request 'HTTP_HOST' => 'www.example.org:80'
-    assert_equal "", request.port_string
+    assert_equal nil, request.optional_port
 
     request = stub_request 'HTTP_HOST' => 'www.example.org:8080'
-    assert_equal ":8080", request.port_string
+    assert_equal 8080, request.optional_port
   end
 
   test "full path" do