Unify hm:t#create and create! implementation

activerecord/lib/active_record/associations/has_many_through_association.rb

@@ -8,25 +8,11 @@ class HasManyThroughAssociation < HasManyAssociation #:nodoc:
       alias_method :new, :build
 
       def create!(attrs = nil)
-        ensure_owner_is_not_new
-
-        transaction do
-          self << (object = attrs ? @reflection.klass.send(:with_scope, :create => attrs) { @reflection.create_association! } : @reflection.create_association!)
-          object
-        end
+        create_record(attrs, true)
       end
 
       def create(attrs = nil)
-        ensure_owner_is_not_new
-
-        transaction do
-          object = attrs ? @reflection.klass.send(:with_scope, :create => attrs) { @reflection.create_association } : @reflection.create_association
-          raise_on_type_mismatch(object)
-          add_record_to_target_with_callbacks(object) do |r|
-            insert_record(object, false)
-          end
-          object
-        end
+        create_record(attrs, false)
       end
 
       def destroy(*records)
@@ -44,8 +30,18 @@ def size
         return @target.size if loaded?
         return count
       end
-      
+
       protected
+        def create_record(attrs, force = true)
+          ensure_owner_is_not_new
+
+          transaction do
+            object = attrs ? @reflection.klass.send(:with_scope, :create => attrs) { @reflection.create_association } : @reflection.create_association
+            add_record_to_target_with_callbacks(object) {|r| insert_record(object, force) }
+            object
+          end
+        end
+
         def target_reflection_has_associated_record?
           if @reflection.through_reflection.macro == :belongs_to && @owner[@reflection.through_reflection.primary_key_name].blank?
             false