1 files changed, 48 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/associations/has_one_association.rb b/activerecord/lib/active_record/associations/has_one_association.rb
new file mode 100644
index 0000000000..74e82f146a
--- /dev/null
+++ b/activerecord/lib/active_record/associations/has_one_association.rb
@@ -0,0 +1,48 @@
+module ActiveRecord
+  module Associations
+    class HasOneAssociation < BelongsToAssociation #:nodoc:
+      def initialize(owner, association_name, association_class_name, association_class_primary_key_name, options)
+        super
+
+        construct_sql
+      end
+
+      def replace(obj, dont_save = false)
+        load_target
+        unless @target.nil?
+          @target[@association_class_primary_key_name] = nil
+          @target.save unless @owner.new_record?
+        end
+
+        if obj.nil?
+          @target = nil
+        else
+          raise_on_type_mismatch(obj)
+          
+          obj[@association_class_primary_key_name] = @owner.id unless @owner.new_record?
+          @target = obj
+        end
+
+        @loaded = true
+        unless @owner.new_record? or obj.nil? or dont_save
+          return (obj.save ? obj : false)
+        else
+          return obj
+        end
+      end
+      
+      private
+        def find_target
+          @association_class.find_first(@finder_sql, @options[:order])
+        end
+
+        def target_obsolete?
+          false
+        end
+
+        def construct_sql
+          @finder_sql = "#{@association_class_primary_key_name} = #{@owner.quoted_id}#{@options[:conditions] ? " AND " + @options[:conditions] : ""}"
+        end
+    end
+  end
+end