Enhance documentation and add examples for url_for. Closes #8227. [jeremymcanally]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@6674 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

2 files changed, 165 insertions, 57 deletions

diff --git a/actionpack/CHANGELOG b/actionpack/CHANGELOG
index 57491941c3..543bb8bb1d 100644
--- a/actionpack/CHANGELOG
+++ b/actionpack/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Enhance documentation and add examples for url_for. [jeremymcanally]
+
 * Fix documentation typo in routes. [norbert, pam]
 
 * Sweep flash when filter chain is halted. [Caio Chassot <lists@v2studio.com>]
diff --git a/actionpack/lib/action_view/helpers/url_helper.rb b/actionpack/lib/action_view/helpers/url_helper.rb
index a573ee1961..ca7e9872cc 100644
--- a/actionpack/lib/action_view/helpers/url_helper.rb
+++ b/actionpack/lib/action_view/helpers/url_helper.rb
@@ -2,20 +2,51 @@ require 'action_view/helpers/javascript_helper'
 
 module ActionView
   module Helpers #:nodoc:
-    # Provides a set of methods for making easy links and getting urls that
-    # depend on the controller and action. This means that you can use the
-    # same format for links in the views that you do in the controller.
+    # Provides a set of methods for making links and getting URLs that
+    # depend on the routing subsystem (see ActionController::Routing). 
+    # This allows you to use the same format for links in views 
+    # and controllers.
     module UrlHelper
       include JavaScriptHelper
 
       # Returns the URL for the set of +options+ provided. This takes the
-      # same options as url_for in action controller. For a list, see the
-      # documentation for ActionController::Base#url_for. Note that it'll
-      # set :only_path => true so you'll get the relative /controller/action
-      # instead of the fully qualified http://example.com/controller/action.
+      # same options as url_for in ActionController (see the
+      # documentation for ActionController::Base#url_for). Note that by default
+      # <tt>:only_path</tt> is <tt>true</tt> so you'll get the relative /controller/action
+      # instead of the fully qualified URL like http://example.com/controller/action.
       #
       # When called from a view, url_for returns an HTML escaped url. If you
       # need an unescaped url, pass :escape => false in the +options+.
+      #
+      # ==== Options
+      # * <tt>:anchor</tt> -- specifies the anchor name to be appended to the path.
+      # * <tt>:only_path</tt> --  if true, returns the relative URL (omitting the protocol, host name, and port) (<tt>true</tt> by default)
+      # * <tt>:trailing_slash</tt> --  if true, adds a trailing slash, as in "/archive/2005/". Note that this
+      #   is currently not recommended since it breaks caching.
+      # * <tt>:host</tt> -- overrides the default (current) host if provided
+      # * <tt>:protocol</tt> -- overrides the default (current) protocol if provided
+      # * <tt>:user</tt> -- Inline HTTP authentication (only plucked out if :password is also present)
+      # * <tt>:password</tt> -- Inline HTTP authentication (only plucked out if :user is also present)
+      # * <tt>:escape</tt> -- Determines whether the returned URL will be HTML escaped or not (<tt>true</tt> by default)
+      #
+      # ==== Examples
+      #   <%= url_for(:action => 'index') %>
+      #   # => /blog/
+      #
+      #   <%= url_for(:action => 'find', :controller => 'books') %>
+      #   # => /books/find
+      #
+      #   <%= url_for(:action => 'login', :controller => 'members', :only_path => false, :protocol => 'https') %>
+      #   # => https://www.railsapplication.com/members/login/
+      #
+      #   <%= url_for(:action => 'play', :anchor => 'player') %>
+      #   # => /messages/play/#player
+      #
+      #   <%= url_for(:action => 'checkout', :anchor => 'tax&ship') %>
+      #   # => /testing/jump/#tax&amp;ship
+      #
+      #   <%= url_for(:action => 'checkout', :anchor => 'tax&ship', :escape => false) %>
+      #   # => /testing/jump/#tax&ship
       def url_for(options = {}, *parameters_for_method_reference)
         if options.kind_of? Hash
           options = { :only_path => true }.update(options.symbolize_keys)
@@ -30,22 +61,20 @@ module ActionView
 
       # Creates a link tag of the given +name+ using a URL created by the set
       # of +options+. See the valid options in the documentation for
-      # ActionController::Base#url_for. It's also possible to pass a string instead
+      # url_for. It's also possible to pass a string instead
       # of an options hash to get a link tag that uses the value of the string as the
       # href for the link. If nil is passed as a name, the link itself will become
       # the name.
       #
-      # The +html_options+ will accept a hash of html attributes for the link tag.
-      # It also accepts 3 modifiers that specialize the link behavior.
-      #
-      # * <tt>:confirm => 'question?'</tt>: This will add a JavaScript confirm
+      # ==== Options
+      # * <tt>:confirm => 'question?'</tt> -- This will add a JavaScript confirm
       #   prompt with the question specified. If the user accepts, the link is
       #   processed normally, otherwise no action is taken.
-      # * <tt>:popup => true || array of window options</tt>: This will force the
+      # * <tt>:popup => true || array of window options</tt> -- This will force the
       #   link to open in a popup window. By passing true, a default browser window
       #   will be opened with the URL. You can also specify an array of options
       #   that are passed-thru to JavaScripts window.open method.
-      # * <tt>:method => symbol of HTTP verb</tt>: This modifier will dynamically
+      # * <tt>:method => symbol of HTTP verb</tt> -- This modifier will dynamically
       #   create an HTML form and immediately submit the form for processing using
       #   the HTTP verb specified. Useful for having links perform a POST operation
       #   in dangerous actions like deleting a record (which search bots can follow
@@ -54,15 +83,27 @@ module ActionView
       #   to using GET. If you are relying on the POST behavior, your should check
       #   for it in your controllers action by using the request objects methods
       #   for post?, delete? or put?.
+      # * The +html_options+ will accept a hash of html attributes for the link tag.
       #
       # You can mix and match the +html_options+ with the exception of
       # :popup and :method which will raise an ActionView::ActionViewError
       # exception.
       #
+      # ==== Examples
       #   link_to "Visit Other Site", "http://www.rubyonrails.org/", :confirm => "Are you sure?"
+      #   # => <a href="http://www.rubyonrails.org/" onclick="return confirm('Are you sure?');">Visit Other Site</a>
+      #
       #   link_to "Help", { :action => "help" }, :popup => true
+      #   # => <a href="/testing/help/" onclick="window.open(this.href);return false;">Help</a>
+      #
       #   link_to "View Image", { :action => "view" }, :popup => ['new_window_name', 'height=300,width=600']
+      #   # => <a href="/testing/view/" onclick="window.open(this.href,'new_window_name','height=300,width=600');return false;">View Image</a>
+      #
       #   link_to "Delete Image", { :action => "delete", :id => @image.id }, :confirm => "Are you sure?", :method => :delete
+      #   # => <a href="/testing/delete/9/" onclick="if (confirm('Are you sure?')) { var f = document.createElement('form'); 
+      #        f.style.display = 'none'; this.parentNode.appendChild(f); f.method = 'POST'; f.action = this.href;
+      #        var m = document.createElement('input'); m.setAttribute('type', 'hidden'); m.setAttribute('name', '_method'); 
+      #        m.setAttribute('value', 'delete'); f.appendChild(m);f.submit(); };return false;">Delete Image</a>
       def link_to(name, options = {}, html_options = nil, *parameters_for_method_reference)
         if html_options
           html_options = html_options.stringify_keys
@@ -90,30 +131,34 @@ module ActionView
       # described in the link_to documentation. If no <tt>:method</tt> modifier
       # is given, it will default to performing a POST operation. You can also
       # disable the button by passing <tt>:disabled => true</tt> in +html_options+.
-      #
-      #   button_to "New", :action => "new"
-      #
-      # Generates the following HTML:
-      #
-      #   <form method="post" action="/controller/new" class="button-to">
-      #     <div><input value="New" type="submit" /></div>
-      #   </form>
-      #
       # If you are using RESTful routes, you can pass the <tt>:method</tt>
       # to change the HTTP verb used to submit the form.
       #
-      #   button_to "Delete Image", { :action => "delete", :id => @image.id },
-      #             :confirm => "Are you sure?", :method => :delete
+      # ==== Options
+      # The +options+ hash accepts the same options at url_for.
       #
-      # Which generates the following HTML:
+      # There are a few special +html_options+:
+      # * <tt>:method</tt> -- specifies the anchor name to be appended to the path.
+      # * <tt>:disabled</tt> -- specifies the anchor name to be appended to the path.
+      # * <tt>:confirm</tt> -- This will add a JavaScript confirm
+      #   prompt with the question specified. If the user accepts, the link is
+      #   processed normally, otherwise no action is taken.
+      # 
+      # ==== Examples
+      #   <%= button_to "New", :action => "new" %>
+      #   # => "<form method="post" action="/controller/new" class="button-to">
+      #   #      <div><input value="New" type="submit" /></div>
+      #   #    </form>"
       #
-      #   <form method="post" action="/images/delete/1" class="button-to">
-      #     <div>
-      #       <input type="hidden" name="_method" value="delete" />
-      #       <input onclick="return confirm('Are you sure?');"
-      #                 value="Delete" type="submit" />
-      #     </div>
-      #   </form>
+      #   button_to "Delete Image", { :action => "delete", :id => @image.id },
+      #             :confirm => "Are you sure?", :method => :delete
+      #   # => "<form method="post" action="/images/delete/1" class="button-to">
+      #   #      <div>
+      #   #        <input type="hidden" name="_method" value="delete" />
+      #   #        <input onclick="return confirm('Are you sure?');"
+      #   #              value="Delete" type="submit" />
+      #   #      </div>
+      #   #    </form>"
       def button_to(name, options = {}, html_options = {})
         html_options = html_options.stringify_keys
         convert_boolean_attributes!(html_options, %w( disabled ))
@@ -140,37 +185,67 @@ module ActionView
 
 
       # Creates a link tag of the given +name+ using a URL created by the set of
-      # +options+ unless the current request uri is the same as the links, in
+      # +options+ unless the current request URI is the same as the links, in
       # which case only the name is returned (or the given block is yielded, if
-      # one exists). Refer to the documentation for link_to_unless for block usage.
+      # one exists).  You can give link_to_unless_current a block which will 
+      # specialize the default behavior (e.g., show a "Start Here" link rather
+      # than the link's text).
+      #
+      # ==== Examples
+      # Let's say you have a navigation menu...
       #
       #   <ul id="navbar">
       #     <li><%= link_to_unless_current("Home", { :action => "index" }) %></li>
       #     <li><%= link_to_unless_current("About Us", { :action => "about" }) %></li>
       #   </ul>
       #
-      # This will render the following HTML when on the about us page:
+      # If in the "about" action, it will render...
       #
       #   <ul id="navbar">
       #     <li><a href="/controller/index">Home</a></li>
       #     <li>About Us</li>
       #   </ul>
+      #
+      # ...but if in the "home" action, it will render:
+      #
+      #   <ul id="navbar">
+      #     <li><a href="/controller/index">Home</a></li>
+      #     <li><a href="/controller/about">About Us</a></li>
+      #   </ul>
+      #
+      # The implicit block given to link_to_unless_current is evaluated if the current
+      # action is the action given.  So, if we had a comments page and wanted to render a 
+      # "Go Back" link instead of a link to the comments page, we could do something like this...
+      #   
+      #    <%= 
+      #        link_to_unless_current("Comment", { :controller => 'comments', :action => 'new}) do
+      #           link_to("Go back", { :controller => 'posts', :action => 'index' }) 
+      #        end 
+      #     %>
       def link_to_unless_current(name, options = {}, html_options = {}, *parameters_for_method_reference, &block)
         link_to_unless current_page?(options), name, options, html_options, *parameters_for_method_reference, &block
       end
 
       # Creates a link tag of the given +name+ using a URL created by the set of
       # +options+ unless +condition+ is true, in which case only the name is
-      # returned. To specialize the default behavior, you can pass a block that
-      # accepts the name or the full argument list for link_to_unless (see the example).
+      # returned. To specialize the default behavior (i.e., show a login link rather
+      # than just the plaintext link text), you can pass a block that
+      # accepts the name or the full argument list for link_to_unless.
       #
+      # ==== Examples
       #   <%= link_to_unless(@current_user.nil?, "Reply", { :action => "reply" }) %>
+      #   # If the user is logged in...
+      #   # => <a href="/controller/reply/">Reply</a>
       #
-      # This example uses a block to modify the link if the condition isn't met.
-      #
-      #   <%= link_to_unless(@current_user.nil?, "Reply", { :action => "reply" }) do |name|
-      #      link_to(name, { :controller => "accounts", :action => "signup" })
-      #    end %>
+      #   <%= 
+      #      link_to_unless(@current_user.nil?, "Reply", { :action => "reply" }) do |name|
+      #        link_to(name, { :controller => "accounts", :action => "signup" })
+      #      end 
+      #   %>
+      #   # If the user is logged in...
+      #   # => <a href="/controller/reply/">Reply</a>
+      #   # If not...
+      #   # => <a href="/accounts/signup">Reply</a>
       def link_to_unless(condition, name, options = {}, html_options = {}, *parameters_for_method_reference, &block)
         if condition
           if block_given?
@@ -188,19 +263,33 @@ module ActionView
       # returned. To specialize the default behavior, you can pass a block that
       # accepts the name or the full argument list for link_to_unless (see the examples
       # in link_to_unless).
+      #
+      # ==== Examples
+      #   <%= link_to_if(@current_user.nil?, "Login", { :controller => "sessions", :action => "new" }) %>
+      #   # If the user isn't logged in...
+      #   # => <a href="/sessions/new/">Login</a>
+      #
+      #   <%= 
+      #      link_to_if(@current_user.nil?, "Login", { :controller => "sessions", :action => "new" }) do
+      #        link_to(@current_user.login, { :controller => "accounts", :action => "show", :id => @current_user })
+      #      end 
+      #   %>
+      #   # If the user isn't logged in...
+      #   # => <a href="/sessions/new/">Login</a>
+      #   # If they are logged in...
+      #   # => <a href="/accounts/show/3">my_username</a>
       def link_to_if(condition, name, options = {}, html_options = {}, *parameters_for_method_reference, &block)
         link_to_unless !condition, name, options, html_options, *parameters_for_method_reference, &block
       end
 
       # Creates a mailto link tag to the specified +email_address+, which is
       # also used as the name of the link unless +name+ is specified. Additional
-      # html attributes for the link can be passed in +html_options+.
+      # HTML attributes for the link can be passed in +html_options+.
       #
       # mail_to has several methods for hindering email harvestors and customizing
       # the email itself by passing special keys to +html_options+.
       #
-      # Special HTML Options:
-      #
+      # ==== Options
       # * <tt>:encode</tt>  - This key will accept the strings "javascript" or "hex".
       #   Passing "javascript" will dynamically create and encode the mailto: link then
       #   eval it into the DOM of the page. This method will not show the link on
@@ -219,20 +308,22 @@ module ActionView
       # * <tt>:cc</tt>  - Carbon Copy addition recipients on the email.
       # * <tt>:bcc</tt>  - Blind Carbon Copy additional recipients on the email.
       #
-      # Examples:
-      #   mail_to "me@domain.com"  # => <a href="mailto:me@domain.com">me@domain.com</a>
-      #   mail_to "me@domain.com", "My email", :encode => "javascript"  # =>
-      #     <script type="text/javascript">eval(unescape('%64%6f%63...%6d%65%6e'))</script>
+      # ==== Examples
+      #   mail_to "me@domain.com" 
+      #   # => <a href="mailto:me@domain.com">me@domain.com</a>
       #
-      #   mail_to "me@domain.com", "My email", :encode => "hex"  # =>
-      #     <a href="mailto:%6d%65@%64%6f%6d%61%69%6e.%63%6f%6d">My email</a>
+      #   mail_to "me@domain.com", "My email", :encode => "javascript"  
+      #   # => <script type="text/javascript">eval(unescape('%64%6f%63...%6d%65%6e'))</script>
       #
-      #   mail_to "me@domain.com", nil, :replace_at => "_at_", :replace_dot => "_dot_", :class => "email"  # =>
-      #     <a href="mailto:me@domain.com" class="email">me_at_domain_dot_com</a>
+      #   mail_to "me@domain.com", "My email", :encode => "hex"  
+      #   # => <a href="mailto:%6d%65@%64%6f%6d%61%69%6e.%63%6f%6d">My email</a>
+      #
+      #   mail_to "me@domain.com", nil, :replace_at => "_at_", :replace_dot => "_dot_", :class => "email"  
+      #   # => <a href="mailto:me@domain.com" class="email">me_at_domain_dot_com</a>
       #
       #   mail_to "me@domain.com", "My email", :cc => "ccaddress@domain.com",
-      #            :subject => "This is an example email"  # =>
-      #     <a href="mailto:me@domain.com?cc=ccaddress@domain.com&subject=This%20is%20an%20example%20email">My email</a>
+      #            :subject => "This is an example email"  
+      #   # => <a href="mailto:me@domain.com?cc=ccaddress@domain.com&subject=This%20is%20an%20example%20email">My email</a>
       def mail_to(email_address, name = nil, html_options = {})
         html_options = html_options.stringify_keys
         encode = html_options.delete("encode").to_s
@@ -280,7 +371,22 @@ module ActionView
         end
       end
 
-      # True if the current request uri was generated by the given +options+.
+      # True if the current request URI was generated by the given +options+.
+      #
+      # ==== Examples
+      # Let's say we're in the <tt>/shop/checkout</tt> action.
+      #
+      #   current_page?(:action => 'process')
+      #   # => false
+      #
+      #   current_page?(:controller => 'shop', :action => 'checkout')
+      #   # => true
+      #
+      #   current_page?(:action => 'checkout')
+      #   # => true
+      #
+      #   current_page?(:controller => 'library', :action => 'checkout')
+      #   # => false
       def current_page?(options)
         url_string = CGI.escapeHTML(url_for(options))
         request = @controller.request