fix Lazy loading breaks STI collection

Signed-off-by: Dan Kubb <dan.kubb@autopilotmarketing.com>

lib/dm-core/collection.rb

@@ -35,7 +35,9 @@ def load(values)
     # @api public
     def reload(query = {})
       @query = scoped_query(query)
-      @query.update(:fields => @query.fields | @key_properties)
+      inheritance_property  = model.base_model.inheritance_property
+      fields  = (@key_properties | [inheritance_property]).compact
+      @query.update(:fields => @query.fields | fields)
       replace(all(:reload => true))
     end
 

lib/dm-core/model.rb

@@ -234,6 +234,10 @@ def key(repository_name = default_repository_name)
       properties(repository_name).key
     end
 
+    def inheritance_property(repository_name = default_repository_name)
+      @properties[repository_name].detect { |property| property.type == DataMapper::Types::Discriminator }
+    end
+
     def default_order(repository_name = default_repository_name)
       @default_order ||= {}
       @default_order[repository_name] ||= key(repository_name).map { |property| Query::Direction.new(property) }

spec/integration/sti_spec.rb

@@ -14,6 +14,7 @@ class ::Book
         property :id,       Serial
         property :title,    String,     :nullable => false
         property :isbn,     Integer,    :nullable => false
+        property :content,  Text
         property :class_type, Discriminator
       end
 
@@ -226,5 +227,46 @@ class ::SpaceWestern < ScienceFiction
         end
       end
     end
+
+    describe "with lazy property" do
+      before :all do
+        Book.auto_migrate!(:sqlite3)
+        repository(:sqlite3) do
+          ShortStory.create(
+            :title => "The Science of Happiness",
+            :isbn => "129038",
+            :content => <<-HERE,
+This doesn’t feel like a normal academic conference. True, the three-day Positive Psychology Summit i
+HERE
+            :moral => "Bullshit might get you to the top, but it won't keep you there.")
+            ShortStory.create(
+              :title => "Blank as white paper",
+              :isbn => "129039",
+              :content => '',
+              :moral => "none.")
+        end
+      end
+
+      it "should be able to access the properties from the parent collection" do
+        repository(:sqlite3) do
+          books = Book.all
+
+          books.each do |book|
+            book.title.should_not be_nil
+            book.isbn.should_not be_nil
+            book.moral.should_not be_nil
+          end
+
+          books[0].content
+
+          books.each do |book|
+            book.title.should_not be_nil
+            book.isbn.should_not be_nil
+            book.moral.should_not be_nil
+          end
+
+        end
+      end
+    end
   end
 end