What calls the setters in an Entity?

Question

In Entity Framework, you must create a class that derives from DbContext with IDbSet properties. What in Entity Framework calls the setters and how does this work?

Answer 1

When your custom context class is instantiated, the base DbContext constructor calls a private method called InitializeLazyInternalContext which in turn calls another private method called DiscoverAndInitializeSets.

This method creates a new instance of a DbSetDiscoveryService, passing in the current context as a constructor parameter, and then calls its InitializeSets method. This method in turn calls GetSets which uses reflection to get a list of any property on the derived context that is assignable from DbSet<T> (this includes IDbSet<T>).

It then loops through this collection and providing the property isn't marked with a SuppressDbSetInitializationAttribute, it assigns an instance of a DbSet<T> by invoking the DbContext's Set<TEntity> method and assigning the result.

You can view the DbSetDiscoveryService code here.

Answer 2

EF uses reflection to discover IDbSet properties on DbContext derived classes and sets them accordingly.