Question

I have two tables with relation:

    modelBuilder.Entity<User>()
        .HasOptional(u => u.Subscription)
        .WithMany();

how can I remove relation?
I want remove Subscription but leave all users.
If I remove subscription EF throw exception:

"The DELETE statement conflicted with the REFERENCE constraint
\"FK_Users_Subscriptions_Subscription_Id\". 
The conflict occurred in database \"db\",table \"dbo.Users\",
column 'Subscription_Id'.\r\nThe statement has been terminated.

And I want have access from user to subscription.

Answer 1

When you delete a subscription you must ensure that the subscription references of all users with that subscription are set to null, otherwise you violate a foreign key constraint in the database. I think, it is enough to load the users with the subscription to delete into the context. EF will fix the relationships automatically:

using (var ctx = new MyContext())
{
    var subscriptionToDelete = ctx.Subscriptions.Find(subscriptionToDeleteId);
    ctx.Users.Where(u => u.Subscription.Id == subscriptionToDeleteId).Load();

    ctx.Subscriptions.Remove(subscriptionToDelete);

    ctx.SaveChanges();
}