Cascade Delete Rule in EF 4.1 Code First when using Shared Primary Key Association

问题

I implemented a bidirectional 1:1 relationship based on this answer:

Primary /Foreign Key in Entity Framework

I define the bidirectional relation this way:

public class Student
{   
    public virtual int StudentId { get; set; }
    public virtual Anamnesis Anamnesis { get; set; }

    . . .
}

public class Anamnesis
{
    [Key, ForeignKey("Student")]
    public int AnamnesisId { get; set; }

    public virtual Student Student { get; set; }

    . . .
}

where, Student is the principal entity and Anamnesis it the entity that shares the PK.

Now I'd like that the relationship created had a Delete Rule = CASCADE. Actually, the relationship that is being created has Delete Rule = NO ACTION as seen in the following picture:

If I manually delete this relation inside the Table Properties window and add other relation with Delete Rule = CASCADE, the code works as I expect allowing me to delete a Student and it's shared Anamnesis that has the same ID.

So, here goes my question:

Is there a way of using Data Annotation (not Fluent API) in my class so that I get a Relation with CASCADE delete rule? I'd prefer using Data Annotation but if it's not possible, I'd be happy with some Fluent API code that makes this work.

NOTE

I have tried the Fluent API code that is shown in this post. It doesn't work in my case where I have bidirectional properties.

回答1:

The following fluent API code perfectly switch on the cascade delete on the database:

public class Student
{   
    public virtual int StudentId { get; set; }
    public virtual Anamnesis Anamnesis { get; set; }
}

public class Anamnesis
{        
    public int AnamnesisId { get; set; }
    public virtual Student Student { get; set; }
}

public class Context : DbContext
{
    public DbSet<Student> Students { get; set; }
    public DbSet<Anamnesis> Anamnesises { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Student>()
                    .HasRequired(s => s.Anamnesis)
                    .WithRequiredPrincipal(a => a.Student)
                    .WillCascadeOnDelete();
    }
}

回答2:

Also, you can use [Required] Attribute, and it will automatically set the delete rule to "CASCADE" mode in related relationship. (and also set "Allow Null" property of that entity to "false" in DB)

来源：https://stackoverflow.com/questions/5825799/cascade-delete-rule-in-ef-4-1-code-first-when-using-shared-primary-key-associati