.net - Generate POCO classes in different project to the project with Entity Framework model

Question

I'm trying to use the Repository Pattern with EF4 using VS2010.

To this end I am using POCO code generation by right clicking on the entity model designer and clicking Add code generation item. I then select the POCO template and get my classes.

What I would like to be able to do is have my solution structured into separate projects for Entity (POCO) classes and another project for the entity model and repository code.

This means that my MVC project could use the POCO classes for strongly typed views etc and not have to know about the repository or have to have a reference to it.

To plug it all together I will have another separate project with interfaces and use IoC.

Sounds good in my head I just don't know how to generate the classes into their own project! I can copy them and then change the namespaces on them but I wanted to avoid manual work whenever I change the schema in the db and want to update my model.

Thanks

Answer 1

Actually the T4 templates in EF 4.0 were designed with this scenario in mind :)

There are 2 templates:

• One for the Entities themselves (i.e. ModelName.tt)
• One for the ObjectContext (i.e. ModelName.Context.tt)

You should put the ModelName.tt file in you POCO project, and just change the template to point to the EDMX file in the persistence aware project.

Sounds weird I know: There is now a dependency, but it is at T4 generation time, not at compile time! And that should be okay? Because the resulting POCO assembly is still completely persistence ignorant.

See steps 5 & 6 of this: http://blogs.msdn.com/adonet/pages/walkthrough-poco-template-for-the-entity-framework.aspx for more.

Hope this helps

Alex