put layout object as embeded obj in design. have bug with solving uploading file

app/views/admin/designs/_form.html.erb

@@ -18,7 +18,7 @@
 <p>
 <%= f.label "layout", t('admin.layout') %>
 <%  if @design.layout.blank? %>
-    <%= f.file_field :layout %>
+    <%= f.file_field :layout_file %>
   <% else%>
     <%= File.basename (Design.all.last.layout.url)  %>
 <% end %>