Can Entity Framework cascade deletes of 1:many for same record types?

Question

I have the following model:

public class Organization
{
    public int Id { get; private set; }
    public Organization? Parent { get; set; }
    public ICollection<Organization>? Children { get; private set; }
}

Now I know, but obviously the database does not, that there will be no cycles in this parent-child set of collections. (An organization is a Country, State, or County.)

As I understand it, SQL Server (my underlying repository) sees the possibility of cycles and throws an exception if asked to perform a cascading delete. Is this correct?

In which case, is my best bet to do:

public class OrganizationConfiguration : IEntityTypeConfiguration<Organization>
{
    /// <inheritdoc />
    public void Configure(EntityTypeBuilder<Organization> builder)
    {
        builder.HasMany(x => x.Children).WithOne(x => x.Parent).OnDelete(DeleteBehavior.ClientSetNull);
    }
}

And then overload my DbContext.SaveChangesAsync and in that, walk children, grandchildren, etc. when an Organization is deleted and delete this (grand)children?

??? - thanks - dave

Answer 1

Hi @David Thielen , Welcome to Microsoft Q&A.

After testing, I added five sets of data to the table, and the deletion was successful through the following code.

            using(var context = new MyDbContext())
            {
                var parentOrganization = await context.organization.Include(x => x.Children).OrderBy(x => x.Id).FirstAsync();

                // Remove parent reference from child organizations
                foreach (var child in parentOrganization.Children)
                {
                    child.Parent = null;
                }

                context.Remove(parentOrganization);
                context.SaveChanges();
            }
            

Best Regards,

Wenbin

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