accept a block in button_to helper

Make possible to use a block in button_to helper if button text is hard
to fit into the name parameter, e.g.:

    <%= button_to [:make_happy, @user] do %>
      Make happy <strong><%= @user.name %></strong>
    <% end %>
    # => "<form method="post" action="/users/1/make_happy" class="button_to">
    #      <div>
    #        <button type="submit">
    #          Make happy <strong>Name</strong>
    #        </button>
    #      </div>
    #    </form>"

actionpack/CHANGELOG.md

 ## Rails 4.0.0 (unreleased) ##
 
+*   Make possible to use a block in button_to helper if button text is hard
+    to fit into the name parameter, e.g.:
+
+        <%= button_to [:make_happy, @user] do %>
+          Make happy <strong><%= @user.name %></strong>
+        <% end %>
+        # => "<form method="post" action="/users/1/make_happy" class="button_to">
+        #      <div>
+        #        <button type="submit">
+        #          Make happy <strong>Name</strong>
+        #        </button>
+        #      </div>
+        #    </form>"
+
+    *Sergey Nartimov*
+
 *   change a way of ordering helpers from several directories. Previously,
     when loading helpers from multiple paths, all of the helpers files were
     gathered into one array an then they were sorted. Helpers from different

actionpack/lib/action_view/helpers/url_helper.rb

@@ -294,6 +294,16 @@ def link_to(*args, &block)
       #   #      <div><input value="New" type="submit" /></div>
       #   #    </form>"
       #
+      #   <%= button_to [:make_happy, @user] do %>
+      #     Make happy <strong><%= @user.name %></strong>
+      #   <% end %>
+      #   # => "<form method="post" action="/users/1/make_happy" class="button_to">
+      #   #      <div>
+      #   #        <button type="submit">
+      #   #          Make happy <strong><%= @user.name %></strong>
+      #   #        </button>
+      #   #      </div>
+      #   #    </form>"
       #
       #   <%= button_to "New", :action => "new", :form_class => "new-thing" %>
       #   # => "<form method="post" action="/controller/new" class="new-thing">
@@ -331,7 +341,16 @@ def link_to(*args, &block)
       #   #       </div>
       #   #     </form>"
       #   #
-      def button_to(name, options = {}, html_options = {})
+      def button_to(*args, &block)
+        if block_given?
+          options      = args[0] || {}
+          html_options = args[1] || {}
+        else
+          name         = args[0]
+          options      = args[1] || {}
+          html_options = args[2] || {}
+        end
+
         html_options = html_options.stringify_keys
         convert_boolean_attributes!(html_options, %w(disabled))
 
@@ -350,9 +369,15 @@ def button_to(name, options = {}, html_options = {})
         request_token_tag = form_method == 'post' ? token_tag : ''
 
         html_options = convert_options_to_data_attributes(options, html_options)
-        html_options.merge!("type" => "submit", "value" => name || url)
+        html_options['type'] = 'submit'
+
+        button = if block_given?
+          content_tag('button', html_options, &block)
+        else
+          tag('input', html_options.merge('value' => name || url))
+        end
 
-        inner_tags = method_tag.safe_concat tag('input', html_options).safe_concat request_token_tag
+        inner_tags = method_tag.safe_concat(button).safe_concat(request_token_tag)
         content_tag('form', content_tag('div', inner_tags), form_options)
       end
 

actionpack/test/template/url_helper_test.rb

@@ -144,6 +144,13 @@ def test_button_to_with_method_get
     )
   end
 
+  def test_button_to_with_block
+    assert_dom_equal(
+      "<form method=\"post\" action=\"http://www.example.com\" class=\"button_to\"><div><button type=\"submit\"><span>Hello</span></button></div></form>",
+      button_to("http://www.example.com") { content_tag(:span, 'Hello') }
+    )
+  end
+
   def test_link_tag_with_straight_url
     assert_dom_equal "<a href=\"http://www.example.com\">Hello</a>", link_to("Hello", "http://www.example.com")
   end