error_messages_for and friends also work with local variables. Closes #9699.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@7779 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

5 files changed, 64 insertions, 6 deletions

diff --git a/actionpack/CHANGELOG b/actionpack/CHANGELOG
index 01e560f79d..f282f70dfc 100644
--- a/actionpack/CHANGELOG
+++ b/actionpack/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* error_messages_for and friends also work with local variables.  #9699 [Frederick Cheung]
+
 * Fix url_for, redirect_to, etc. with :controller => :symbol instead of 'string'.  #8562, #9525 [Justin Lynn, Tarmo Tänav, shoe]
 
 * Use #require_library_or_gem to load the memcache library for the MemCache session and fragment cache stores.  Closes #8662. [Rick]
diff --git a/actionpack/lib/action_view/helpers/active_record_helper.rb b/actionpack/lib/action_view/helpers/active_record_helper.rb
index 08abdbd8a8..e2e35cb0bd 100644
--- a/actionpack/lib/action_view/helpers/active_record_helper.rb
+++ b/actionpack/lib/action_view/helpers/active_record_helper.rb
@@ -76,16 +76,21 @@ module ActionView
 
       # Returns a string containing the error message attached to the +method+ on the +object+ if one exists.
       # This error message is wrapped in a <tt>DIV</tt> tag, which can be extended to include a +prepend_text+ and/or +append_text+
-      # (to properly explain the error), and a +css_class+ to style it accordingly. As an example, let's say you have a model
+      # (to properly explain the error), and a +css_class+ to style it accordingly. +object+ should either be the name of an instance variable or
+      # the actual object. As an example, let's say you have a model
       # +post+ that has an error message on the +title+ attribute:
       #
       #   <%= error_message_on "post", "title" %> =>
       #     <div class="formError">can't be empty</div>
       #
+      #   <%= error_message_on @post, "title" %> =>
+      #     <div class="formError">can't be empty</div>
+      #
       #   <%= error_message_on "post", "title", "Title simply ", " (or it won't work).", "inputError" %> =>
       #     <div class="inputError">Title simply can't be empty (or it won't work).</div>
       def error_message_on(object, method, prepend_text = "", append_text = "", css_class = "formError")
-        if (obj = instance_variable_get("@#{object}")) && (errors = obj.errors.on(method))
+        if (obj = (object.respond_to?(:errors) ? object : instance_variable_get("@#{object}"))) &&
+          (errors = obj.errors.on(method))
           content_tag("div", "#{prepend_text}#{errors.is_a?(Array) ? errors.first : errors}#{append_text}", :class => css_class)
         else 
           ''
@@ -101,6 +106,8 @@ module ActionView
       # * <tt>header_tag</tt> - Used for the header of the error div (default: h2)
       # * <tt>id</tt> - The id of the error div (default: errorExplanation)
       # * <tt>class</tt> - The class of the error div (default: errorExplanation)
+      # * <tt>object</tt> - The object (or array of objects) for which to display errors, 
+      # if you need to escape the instance variable convention
       # * <tt>object_name</tt> - The object name to use in the header, or
       # any text that you prefer. If <tt>object_name</tt> is not set, the name of
       # the first object will be used.
@@ -114,12 +121,21 @@ module ActionView
       #
       #   error_messages_for 'user_common', 'user', :object_name => 'user'
       #
+      # If the objects cannot be located as instance variables, you can add an extra +object+ paremeter which gives the actual
+      # object (or array of objects to use)
+      #
+      #   error_messages_for 'user', :object => @question.user
+      #
       # NOTE: This is a pre-packaged presentation of the errors with embedded strings and a certain HTML structure. If what
       # you need is significantly different from the default presentation, it makes plenty of sense to access the object.errors
       # instance yourself and set it up. View the source of this method to see how easy it is.
       def error_messages_for(*params)
         options = params.extract_options!.symbolize_keys
-        objects = params.collect {|object_name| instance_variable_get("@#{object_name}") }.compact
+        if object = options.delete(:object)
+          objects = [object].flatten
+        else
+          objects = params.collect {|object_name| instance_variable_get("@#{object_name}") }.compact
+        end
         count   = objects.inject(0) {|sum, object| sum + object.errors.count }
         unless count.zero?
           html = {}
diff --git a/actionpack/lib/action_view/helpers/form_helper.rb b/actionpack/lib/action_view/helpers/form_helper.rb
index 9bfc3041af..3b4e05bc1d 100644
--- a/actionpack/lib/action_view/helpers/form_helper.rb
+++ b/actionpack/lib/action_view/helpers/form_helper.rb
@@ -628,11 +628,11 @@ module ActionView
       end
       
       def error_message_on(method, prepend_text = "", append_text = "", css_class = "formError")
-        @template.error_message_on(@object_name, method, prepend_text, append_text, css_class)
+        @template.error_message_on(@object, method, prepend_text, append_text, css_class)
       end      
 
       def error_messages(options = {})
-        @template.error_messages_for(@object_name, options)
+        @template.error_messages_for(@object_name, options.merge(:object => @object))
       end
       
       def submit(value = "Save changes", options = {})
diff --git a/actionpack/test/template/active_record_helper_test.rb b/actionpack/test/template/active_record_helper_test.rb
index 4a85ae1751..4630cbc1f3 100644
--- a/actionpack/test/template/active_record_helper_test.rb
+++ b/actionpack/test/template/active_record_helper_test.rb
@@ -181,6 +181,11 @@ class ActiveRecordHelperTest < Test::Unit::TestCase
     assert_dom_equal "<div class=\"formError\">can't be empty</div>", error_message_on(:post, :author_name)
   end
 
+  def test_error_message_on_no_instance_variable
+    other_post = @post
+    assert_dom_equal "<div class=\"formError\">can't be empty</div>", error_message_on(other_post, :author_name)
+  end
+  
   def test_error_message_on_should_use_options
     assert_dom_equal "<div class=\"differentError\">beforecan't be emptyafter</div>", error_message_on(:post, :author_name, "before", "after", "differentError")
   end
@@ -203,7 +208,23 @@ class ActiveRecordHelperTest < Test::Unit::TestCase
     # should space object name
     assert_dom_equal %(<div class="errorExplanation" id="errorExplanation"><h2>2 errors prohibited this chunky bacon from being saved</h2><p>There were problems with the following fields:</p><ul><li>User email can't be empty</li><li>Author name can't be empty</li></ul></div>), error_messages_for(:user, :post, :object_name => "chunky_bacon")
   end
-
+  
+  def test_error_messages_for_non_instance_variable
+    actual_user = @user
+    actual_post = @post
+    @user = nil
+    @post = nil
+
+  #explicitly set object
+    assert_dom_equal %(<div class="errorExplanation" id="errorExplanation"><h2>1 error prohibited this post from being saved</h2><p>There were problems with the following fields:</p><ul><li>Author name can't be empty</li></ul></div>), error_messages_for("post", :object => actual_post)
+      
+  #multiple objects
+    assert_dom_equal %(<div class="errorExplanation" id="errorExplanation"><h2>2 errors prohibited this user from being saved</h2><p>There were problems with the following fields:</p><ul><li>User email can't be empty</li><li>Author name can't be empty</li></ul></div>), error_messages_for("user", "post", :object => [actual_user, actual_post])
+    
+  #nil object
+    assert_equal '', error_messages_for('user', :object => nil)
+  end
+  
   def test_form_with_string_multipart
     assert_dom_equal(
       %(<form action="create" enctype="multipart/form-data" method="post"><p><label for="post_title">Title</label><br /><input id="post_title" name="post[title]" size="30" type="text" value="Hello World" /></p>\n<p><label for="post_body">Body</label><br /><div class="fieldWithErrors"><textarea cols="40" id="post_body" name="post[body]" rows="20">Back to the hill and over it again!</textarea></div></p><input name="commit" type="submit" value="Create" /></form>),
diff --git a/actionpack/test/template/form_helper_test.rb b/actionpack/test/template/form_helper_test.rb
index 1c842fc307..32529c66f7 100644
--- a/actionpack/test/template/form_helper_test.rb
+++ b/actionpack/test/template/form_helper_test.rb
@@ -527,6 +527,25 @@ class FormHelperTest < Test::Unit::TestCase
     assert_dom_equal expected, _erbout
 
   end
+  
+  def test_default_form_builder_no_instance_variable
+    post = @post
+    @post = nil
+    
+    _erbout = '' 
+    form_for(:post, post) do |f|
+       _erbout.concat f.error_message_on('author_name')
+       _erbout.concat f.error_messages
+    end    
+    
+    expected = %(<form action='http://www.example.com' method='post'>) + 
+               %(<div class='formError'>can't be empty</div>) + 
+               %(<div class="errorExplanation" id="errorExplanation"><h2>1 error prohibited this post from being saved</h2><p>There were problems with the following fields:</p><ul><li>Author name can't be empty</li></ul></div>) +
+               %(</form>)
+    
+    assert_dom_equal expected, _erbout
+    
+  end
 
   # Perhaps this test should be moved to prototype helper tests.
   def test_remote_form_for_with_labelled_builder