Make `content_tag_for` and `div_for` accepts the array of records

So instead of having to do this:

   @items.each do |item|
     content_tag_for(:li, item) do
        Title: <%= item.title %>
     end
   end

You can now do this:

   content_tag_for(:li, @items) do |item|
     Title: <%= item.title %>
   end

actionpack/CHANGELOG

 *Rails 3.2.0 (unreleased)*
 
+* content_tag_for and div_for can now take the collection of records. It will also yield the record as the first argument if you set a receiving argument in your block [Prem Sichanugrist]
+
+  So instead of having to do this:
+
+    @items.each do |item|
+      content_tag_for(:li, item) do
+         Title: <%= item.title %>
+      end
+    end
+
+  You can now do this:
+
+    content_tag_for(:li, @items) do |item|
+      Title: <%= item.title %>
+    end
+
 * send_file now guess the mime type [Esad Hajdarevic]
 
 * Mime type entries for PDF, ZIP and other formats were added [Esad Hajdarevic]

actionpack/lib/action_view/helpers/record_tag_helper.rb

@@ -17,6 +17,19 @@ module RecordTagHelper
       #
       #    <div id="person_123" class="person foo"> Joe Bloggs </div>
       #
+      # You can also pass an array of Active Record objects, which will then
+      # get iterates over and yield each record as an argument for the block.
+      # For example:
+      #
+      #    <%= div_for(@people, :class => "foo") do |person| %>
+      #      <%= person.name %>
+      #    <% end %>
+      #
+      # produces:
+      #
+      #    <div id="person_123" class="person foo"> Joe Bloggs </div>
+      #    <div id="person_124" class="person foo"> Jane Bloggs </div>
+      #
       def div_for(record, *args, &block)
         content_tag_for(:div, record, *args, &block)
       end
@@ -42,6 +55,21 @@ def div_for(record, *args, &block)
       #
       #    <tr id="foo_person_123" class="person">...
       #
+      # You can also pass an array of objects which this method will loop through
+      # and yield the current object to the supplied block, reduce the need for
+      # having to iterate through the object (using <tt>each</tt>) beforehand.
+      # For example (assuming @people is an array of Person objects):
+      #
+      #    <%= content_tag_for(:tr, @people) do |person| %>
+      #      <td><%= person.first_name %></td>
+      #      <td><%= person.last_name %></td>
+      #    <% end %>
+      #
+      # produces:
+      #
+      #   <tr id="person_123" class="person">...</tr>
+      #   <tr id="person_124" class="person">...</tr>
+      #
       # content_tag_for also accepts a hash of options, which will be converted to
       # additional HTML attributes. If you specify a <tt>:class</tt> value, it will be combined
       # with the default class name for your object. For example:
@@ -52,12 +80,30 @@ def div_for(record, *args, &block)
       #
       #    <li id="person_123" class="person bar">...
       #
-      def content_tag_for(tag_name, record, prefix = nil, options = nil, &block)
-        options, prefix = prefix, nil if prefix.is_a?(Hash)
-        options ||= {}
-        options.merge!({ :class => "#{dom_class(record, prefix)} #{options[:class]}".strip, :id => dom_id(record, prefix) })
-        content_tag(tag_name, options, &block)
+      def content_tag_for(tag_name, single_or_multiple_records, prefix = nil, options = nil, &block)
+        if single_or_multiple_records.respond_to?(:to_ary)
+          single_or_multiple_records.to_ary.map do |single_record|
+            capture { content_tag_for_single_record(tag_name, single_record, prefix, options, &block) }
+          end.join("\n")
+        else
+          content_tag_for_single_record(tag_name, single_or_multiple_records, prefix, options, &block)
+        end
       end
+
+      private
+
+        # Called by <tt>content_tag_for</tt> internally to render a content tag
+        # for each record.
+        def content_tag_for_single_record(tag_name, record, prefix, options, &block)
+          options, prefix = prefix, nil if prefix.is_a?(Hash)
+          options ||= {}
+          options.merge!({ :class => "#{dom_class(record, prefix)} #{options[:class]}".strip, :id => dom_id(record, prefix) })
+          if block.arity == 0
+            content_tag(tag_name, capture(&block), options)
+          else
+            content_tag(tag_name, capture(record, &block), options)
+          end
+        end
     end
   end
 end

actionpack/test/template/record_tag_helper_test.rb

@@ -4,11 +4,12 @@
 class Post
   extend ActiveModel::Naming
   include ActiveModel::Conversion
+  attr_writer :id, :body
   def id
-     45
+     @id || 45
   end
   def body
-    super || "What a wonderful world!"
+    super || @body || "What a wonderful world!"
   end
 end
 
@@ -58,4 +59,23 @@ def test_div_for_in_erb
     actual = div_for(@post, :class => "bar") { concat @post.body }
     assert_dom_equal expected, actual
   end
+
+  def test_content_tag_for_collection
+    post_1 = Post.new.tap { |post| post.id = 101; post.body = "Hello!"; post.persisted = true }
+    post_2 = Post.new.tap { |post| post.id = 102; post.body = "World!"; post.persisted = true }
+    expected = %(<li class="post" id="post_101">Hello!</li>\n<li class="post" id="post_102">World!</li>)
+    actual = content_tag_for(:li, [post_1, post_2]) { |post| concat post.body }
+    assert_dom_equal expected, actual
+  end
+
+  def test_content_tag_for_collection_is_html_safe
+  end
+
+  def test_div_for_collection
+    post_1 = Post.new.tap { |post| post.id = 101; post.body = "Hello!"; post.persisted = true }
+    post_2 = Post.new.tap { |post| post.id = 102; post.body = "World!"; post.persisted = true }
+    expected = %(<div class="post" id="post_101">Hello!</div>\n<div class="post" id="post_102">World!</div>)
+    actual = div_for([post_1, post_2]) { |post| concat post.body }
+    assert_dom_equal expected, actual
+  end
 end

railties/guides/source/action_view_overview.textile

@@ -454,6 +454,83 @@ input("post", "title") # =>
   <input id="post_title" name="post[title]" size="30" type="text" value="Hello World" />
 </ruby>
 
+h4. RecordTagHelper
+
+This module provides methods for generating a container tag, such as a +<div>+, for your record. This is the recommended way of creating a container for render your Active Record object, as it adds an appropriate class and id attributes to that container. You can then refer to those containers easily by following the convention, instead of having to think about which class or id attribute you should use.
+
+h5. content_tag_for
+
+Renders a container tag that relates to your Active Record Object.
+
+For example, given +@post+ is the object of +Post+ class, you can do:
+
+<ruby>
+<%= content_tag_for(:tr, @post) do %>
+  <td><%= @post.title %></td>
+<% end %>
+</ruby>
+
+This will generate this HTML output:
+
+<html>
+<tr id="post_1234" class="post">
+  <td>Hello World!</td>
+</tr>
+</html>
+
+You can also supply HTML attributes as an additional option hash. For example:
+
+<ruby>
+<%= content_tag_for(:tr, @post, :class => "frontpage") do %>
+  <td><%= @post.title %></td>
+<% end %>
+</ruby>
+
+Will generate this HTML output:
+
+<html>
+<tr id="post_1234" class="post frontpage">
+  <td>Hello World!</td>
+</tr>
+</html>
+
+You can pass a collection of Active Record objects. This method will loops through your objects and create a container for each of them. For example, given +@posts+ is an array of two +Post+ objects:
+
+<ruby>
+<%= content_tag_for(:tr, @posts) do |post| %>
+  <td><%= post.title %></td>
+<% end %>
+</ruby>
+
+Will generate this HTML output:
+
+<html>
+<tr id="post_1234" class="post">
+  <td>Hello World!</td>
+</tr>
+<tr id="post_1235" class="post">
+  <td>Ruby on Rails Rocks!</td>
+</tr>
+</html>
+
+h5. div_for
+
+This is actually a convenient method which calls +content_tag_for+ internally with +:div+ as the tag name. You can pass either an Active Record object or a collection of objects. For example:
+
+<ruby>
+<%= div_for(@post, :class => "frontpage") do %>
+  <td><%= @post.title %></td>
+<% end %>
+</ruby>
+
+Will generate this HTML output:
+
+<html>
+<div id="post_1234" class="post frontpage">
+  <td>Hello World!</td>
+</div>
+</html>
+
 h4. AssetTagHelper
 
 This module provides methods for generating HTML that links views to assets such as images, JavaScript files, stylesheets, and feeds.