Fix bug when simple_fields_for is used with a hask like model

Thanks to @rafaelfranca and @spohlenz fixing in simple_form and Rails!

See:
heartcombo/simple_form@14b6263
rails/rails#1778

ref formtastic#568

lib/formtastic/helpers/form_helper.rb

@@ -166,7 +166,7 @@ def semantic_form_for(record_or_name_or_array, *args, &proc)
       #
       # @see #semantic_form_for
       def semantic_fields_for(record_name, record_object = nil, options = {}, &block)
-        options, record_object = record_object, nil if record_object.is_a?(Hash)
+        options, record_object = record_object, nil if record_object.is_a?(Hash) && record_object.extractable_options?
         options[:builder] ||= @@builder
         @@builder.custom_namespace = options[:namespace].to_s # TODO needed?
 

spec/builder/semantic_fields_for_spec.rb

@@ -22,6 +22,9 @@
       semantic_fields_for(:author, @new_post.author) do |nested_builder|
         nested_builder.class.should == Formtastic::Helpers::FormHelper.builder
       end
+      semantic_fields_for(:author, @hash_backed_author) do |nested_builder|
+        nested_builder.class.should == Formtastic::Helpers::FormHelper.builder
+      end
     end
 
     it 'should respond to input' do
@@ -34,6 +37,9 @@
       semantic_fields_for(:author, @new_post.author) do |nested_builder|
         nested_builder.respond_to?(:input).should be_true
       end
+      semantic_fields_for(:author, @hash_backed_author) do |nested_builder|
+        nested_builder.respond_to?(:input).should be_true
+      end
     end
   end
 
@@ -46,6 +52,14 @@
       end
     end
 
+    it 'yields an instance of FormHelper.builder with hash-like model' do
+      semantic_form_for(:user) do |builder|
+        builder.semantic_fields_for(:author, @hash_backed_author) do |nested_builder|
+          nested_builder.class.should == Formtastic::Helpers::FormHelper.builder
+        end
+      end
+    end
+
     it 'nests the object name' do
       semantic_form_for(@new_post) do |builder|
         builder.semantic_fields_for(@bob) do |nested_builder|
@@ -113,4 +127,3 @@
   end
 
 end
-

spec/spec_helper.rb

@@ -93,6 +93,7 @@ def id
     def persisted?
     end
   end
+
   module ::Namespaced
     class Post
       extend ActiveModel::Naming if defined?(ActiveModel::Naming)
@@ -105,6 +106,7 @@ def persisted?
       end
     end
   end
+
   class ::Author
     extend ActiveModel::Naming if defined?(ActiveModel::Naming)
     include ActiveModel::Conversion if defined?(ActiveModel::Conversion)
@@ -115,10 +117,21 @@ def to_label
     def persisted?
     end
   end
+
+  class ::HashBackedAuthor < Hash
+    extend ActiveModel::Naming if defined?(ActiveModel::Naming)
+    include ActiveModel::Conversion if defined?(ActiveModel::Conversion)
+    def persisted?; false; end
+    def name
+      'hash backed author'
+    end
+  end
+
   class ::Continent
     extend ActiveModel::Naming if defined?(ActiveModel::Naming)
     include ActiveModel::Conversion if defined?(ActiveModel::Conversion)
   end
+
   class ::PostModel
     extend ActiveModel::Naming if defined?(ActiveModel::Naming)
     include ActiveModel::Conversion if defined?(ActiveModel::Conversion)
@@ -209,6 +222,8 @@ def new_author_path; "/authors/new"; end
     ::Author.stub!(:to_key).and_return(nil)
     ::Author.stub!(:persisted?).and_return(nil)
 
+    @hash_backed_author = HashBackedAuthor.new
+
     # Sometimes we need a mock @post object and some Authors for belongs_to
     @new_post = mock('post')
     @new_post.stub!(:class).and_return(::Post)