Question
I have this:
public class Foo
{
public int Id { get; set; }
public Bar Bar { get; set; }
}
public class Bar
{
public int Something { get; set; }
public int SomethingElse { get; set; }
}
and my database is like this:
CREATE TABLE [Foo](
[Id] INT,
[Bar_Something] INT NOT NULL,
[Bar_SomethingElse] INT NOT NULL,
)
When I get the DB context with
public class DB: DbContext
{
public DbSet<Foo> Foo { get; set; }
}
Foo.Id is mapped correctly but Bar cannot be mapped with this error System.InvalidOperationException : The entity type 'Bar' requires a primary key to be defined.
I don't want to create Bar table and give its id as FK to Foo.
How can I map the columns Bar_Something and Bar_SomethingElse to Foo.Bar.Something and Foo.Bar.SomethingElse?
Accepted Answer
EF Core 2.0 and later support Owned entity types. By default, those are mapped using Table splitting.
In EF Core 2.1, you probably only need to add the [Owned] attribute to Bar, ie :
[Owned]
public class Bar
{
public int Something { get; set; }
public int SomethingElse { get; set; }
}
The owned type's properties will be mapped to fields in the same table named Property_OwnedProperty. In this case it will be Bar_Something and Bar_SomethingElse
Looks like someone designed the table with those requirements in mind.
In EF Core 2.0 you need to specify the owned type in the context configuration :
modelBuilder.Entity<Foo>().OwnsOne(p => p.Bar);
Popular Answer
a primary key to be defined in your Bar class.
public class Bar
{
[Key]
public int Something { get; set; }
public int SomethingElse { get; set; }
}
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