OwnedEntityTypes

An example how to use Owned Entity Types in EntityFramework Core,
see it in action https://ownedentitytypes-vitalmente.azurewebsites.net/ !

With Owned Entity Types you can create sub entities for your EF Core entities.
Imagine you have a Person entity and you want to add an Address entity.

The resulting Person entity will be:

public class Person {
    public string Id {get; set;}
    public string FirstName {get; set;}
    public string LastName {get; set;}
    /* Address fields */
    public string Street {get; set;}
    public string City {get; set;}
    public string Country {get; set;}
}

Now imagine that you want to create a reusable class for all kind of Address.
Tipically the solution is to create a joined table with a foreign key.

This is the reason why the Owned Entity Types have been invented: to simplify the development of related entities.

In action we have:

[Owned]
public class Address {
    public string Street {get; set;}
    public string City {get; set;}
    public string Country {get; set;}
}

public class Person {
    public string Id {get; set;}
    public string FirstName {get; set;}
    public string LastName {get; set;}
    public Address StreetAddress {get; set;}
}

Now we have a navigation like Person.StreetAddress.City.

On the database the EF Core works its magic:

Field	Type
Id	int
FirstName	nvarchar(MAX)
LastName	nvarchar(MAX)
StreetAddress_Street	nvarchar(MAX)
StreetAddress_City	nvarchar(MAX)
StreetAddress_Country	nvarchar(MAX)

Assigning values

Look at this piece of code for an example of assigning values:

var person = new Person();
person.FirstName = 'Ted';
person.LastName = 'Wilson';
person.StreetAddress = new Address();
person.StreetAddress.City = 'London';

_context.Person.Add(person);
_context.SaveChanges();

or

var person = new Person();
person.FirstName = 'Ted';
person.LastName = 'Wilson';

var streetAddress = new Address();
streetAddress.City = 'London';

person.StreetAddress = streetAddress;

_context.Person.Add(person);
_context.SaveChanges();