Creating custom Odata Service

Hi All

I am having a problem, while creating custom Odata service. I have done with Data Model and  i have generated the project. Now i have done the code in DPC. And getting the result perfectly.

Now i am creating a another entity in the same project. After generating it again , when i check my previous entity method which was working fine, has been refreshed. There is no code available in the Entity Method.

Please help me, How and where i need to do the code for the entity?

Thanks

Arjun