EFCore nullable relationship setting onDelete: ReferentialAction.Restrict

Question

I\'m running efcore 2.0.1.

I have a model:

public class BigAwesomeDinosaurWithTeeth
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identi         


        

Answer 1

EF Core 2.0.1 metadata and migrations use different enums for specifying the delete behavior - respectively DeleteBehavior and ReferentialAction. While the first is well documented, the second and the mapping between the two is not (at the time of writing).

Here is the current mapping:

DeleteBehavior    ReferentialAction
==============    =================
Cascade           Cascade
ClientSetNull     Restrict
Restrict          Restrict
SetNull           SetNull

In your case, the relationship is optional, hence the DeleteBehavior by convention is ClientSetNull which maps to onDelete: Restrict, or in other words, enforced (enabled) FK w/o cascade delete.

If you want different behavior, you have to use fluent API, e.g.

modelBuilder.Entity<BigAwesomeDinosaurWithTeeth>()
    .HasMany(e => e.YummyPunyPrey)
    .WithOne(e => e.BigAwesomeDinosaurWithTeeth)
    .OnDelete(DeleteBehavior.SetNull); // or whatever you like