Understanding owned entities
In the previous sections, we have learned some relationships are optional, but some are required. For example, a post can exist without a category, but a student ID card cannot exist without a student. For the latter, we can say a student owns an ID card. Similarly, a contact owns an address. We can also find some examples of one-to-many relationships. For example, an invoice owns many invoice items because an invoice item cannot exist without an invoice. In this section, we will introduce the concept of owned entities.
Owned entity types are entity types that are part of the owner and cannot exist without the owner. You can use common one-to-one or one-to-many relationships to model the owned entities, but EF Core provides a more convenient way called owned entity types. You can use the OwnsOne() or OwnsMany() method to define owned entity types, instead of using the HasOne() or HasMany() method. For example, to configure the InvoiceItem entity as an...
