删除包含DbSet对象的DbSet对象

Question

I have coded a C# MVC5 internet application, where I have a MapCompany object that has a List<MapLocation> . I have a DbSet<MapCompany> as well as a DbSet<MapLocation> . When I call the Delete Action result when trying to delete a MapCompany object, I am getting the following error:

The DELETE statement conflicted with the REFERENCE constraint "FK_dbo.MapLocations_dbo.MapCompanies_MapCompany_Id". The conflict occurred in database "TestDatabase", table "dbo.MapLocations", column 'MapCompany_Id'.
The statement has been terminated.

Do I need to remove all the associated MapLocations when removing a MapCompany object? If so, what is the easiest way to do this? Is there an easier/better way rather than looping through each object, and removing each object manually? Also, at a future stage, each MapLocation will have many MapLocationItem objects.

Answer 1

Manual

Delete the items manually. This is sometimes the preferred option as it gives you full control.

Cascaded Deletes

You can set the foreign key relationship to cascade deletes. This means that deleting the parent record will delete all records from the table that references it. To enable cascaded deletes on a table, read this answer .

Alternatively if you are using code first development, you can enable cascading deletes using the fluent API:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<MapCompany>()
        .HasOptional(a => a.MapLocations)
        .WithOptionalDependent()
        .WillCascadeOnDelete(true);
}

Here is a good discussion on the pros/cons of cascaded deletes: What are the Pros and Cons of Cascading delete and updates?