Entity Framework Core Cookbook - Second Edition

References not eagerly fetched are lost

If you don't explicitly ask for related entities when you load an entity, you won't be able to do it later.

Problem

Object-Relational Mappers (ORMs) typically have a feature called lazy loading. Lazy loading means that when an entity is loaded from the database, all its relations (one-to-one, one-to-many, many-to-one, many-to-many) do not necessarily need to be loaded too. When they are first accessed, the ORM will issue a query and retrieve the records. This is interesting, because we do not need to pay the extra cost of loading potentially a lot of records if we are not going to use them. On the other hand, it requires that a connection is always available when the lazy properties are first accessed, otherwise ...