Question

I've seen this before but haven't found concrete reasons.

When you add Entities to your EF model, EF auto generates classes for these entities.

In terms of DataAccess, why is it preferred to not use these Auto Generated Classes, and instead use your own Data Models for Data Access.

Ex.

EFAutoGeneratedClass = //query = BAD

SeparateModelClass = //query = Good

Answer 1

If you database changes, your auto-generated entities will change upon a refresh of it's schema. You don't want these changes to break your code, but if you depend on them, it might break your code (in many places as oppose to one place if you transfer the entity content over to your own model)