EF CodeFirst Mapping Two Cascade Delete Relationships

Question

I have some issues getting cascading to work on my optional one-to-one and one-to-many relation. Enabling 1 of them works fine but enabling both results in a 'possible circular cascading exception'.

I have a 'Customer' which has multiple 'DeliverAddresses' and one 'VisitAddress'. So for address I have an optional DeliverAddressForCustomer and an optional VisitAddressForCustomer.

this results in the following tables:

CREATE TABLE [dbo].[Customer]
(
    [Id] INT NOT NULL PRIMARY KEY IDENTITY
    [Name] NVARCHAR(50) NOT NULL,
)

CREATE TABLE [dbo].[Address]
(
    [Id] INT NOT NULL PRIMARY KEY IDENTITY, 
    [Street] NVARCHAR(50) NOT NULL,
    [DeliverAddressForCustomerId] INT NULL, 
    [VisitAddressForCustomer] INT NULL, 
    CONSTRAINT [FK_Address_Customer_DeliverAddressForCustomerId] FOREIGN KEY ([DeliverAddressForCustomerId]) REFERENCES [Customer]([Id]), 
    CONSTRAINT [FK_Address_Customer_VisitAddressForCustomerId] FOREIGN KEY ([VisitAddressForCustomerId]) REFERENCES [Customer]([Id])
)

This works with the following mapping:

        this.ToTable("Address");
        this.Property(t => t.Id).HasColumnName("Id");
        this.Property(t => t.Postcode).HasColumnName("Postcode");
        this.Property(t => t.DeliverAddressForCustomerId).HasColumnName("DeliverAddressForCustomerId");

        // Relationships
        this.HasOptional(t => t.DeliverAddressForCustomer)
            .WithMany(t => t.DeliverAddresses)
            .HasForeignKey(d => d.DeliverAddressForCustomerId)
            .WillCascadeOnDelete(true);

        this.HasOptional(a => a.VisitAddressForCustomer)
            .WithOptionalDependent(k => k.VisitAddress)
            .Map(x => x.MapKey("VisitAddressForCustomerId"))
            .WillCascadeOnDelete(true);

Now if I have both 'WillCascadeOnDelete' set to true, it will work with an existing DB but not if I want to create the DB... I get the following exception message:

Introducing FOREIGN KEY constraint 'FK_dbo.Address_dbo.Address_Customer_VisitAddressForCustomerId' on table 'Address' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.

But this doesn't make sense to me since if I delete a deliveryAddress or a visitAddress, customer should stay untouched in this setting. So there should be no circular cascading.

Answer 1

The message says "may cause cycles or multiple cascade paths". It's the last part that matters. SQL server won't allow more than one FK constraint with cascaded deletes in one table.

By the way, note that cascaded delete does not prescribe what should happen if you delete an Address, but if you delete a Customer.

Also see this: SQL Server 2008 - Multiple Cascading FK's - Do i need a trigger?