Entity Framework EF Code First Cascade Delete for One-to-Zero-or-One relationship

Question

Following the  Code First Modeling  section of the Pluralsight  Getting Started with Entity Framework 5  course by Julie Lerman  I created two POCO classes with a one-to-zero-or-one relationship  a parent  User  and an optional child  UserDetail    User and UserDetail data model diagram  click to view    Notice in the diagram that the UserId property is a primary key and a foreign key for UserDetail   Relevant code   public class User                   Key       DatabaseGenerated DatabaseGeneratedOption Identity       public int UserId   get  set            Has a 1 0  1 relationship with UserDetail        public virtual UserDetail UserDetail   get  set                  public class UserDetail                     Has a 0  1 1 relationship with User        public virtual User User   get  set          Key  ForeignKey  User        public int UserId   get  set                  public class EFDbContext   DbContext       public DbSet lt User gt  Users   get  set          public DbSet lt UserDetail gt  UserDetails   get  set        Explicit declaration not necessary  Context is aware of UserDetail entity due to 0  1 1 relationship with User         public EFDbContext                 Configuration ProxyCreationEnabled   true          Configuration LazyLoadingEnabled   true           public class UserRepository   IUserRepository       private EFDbContext  context   new EFDbContext         public void Delete User entity                entity    context Users Find entity UserId                            context Users Remove entity            context SaveChanges                             When the Delete   method in the UserRepository class is called  it does not delete the User record in the database because the foreign key in UserDetail does not have cascade delete enabled      The DELETE statement conflicted with the REFERENCE constraint  FK dbo UserDetail dbo User UserId     How would you enable cascading deletes for one-to-zero-or-one relationships using Entity Framework Code First  so that deleting a User automatically deletes UserDetail

User · Answer

This code worked for me  protected override void OnModelCreating DbModelBuilder modelBuilder                modelBuilder Entity lt UserDetail gt                 HasRequired d   gt  d User               WithOptional u   gt  u UserDetail               WillCascadeOnDelete true           The migration code was    public override void Up                 AddForeignKey  UserDetail    UserId    User    UserId   cascadeDelete  true           And it worked fine  When I first used   modelBuilder Entity lt User gt         HasOptional a   gt  a UserDetail       WithOptionalDependent        WillCascadeOnDelete true     The migration code was    AddForeignKey  User    UserDetail UserId    UserDetail    UserId   cascadeDelete  true      but it does not match any of the two overloads available  in EntityFramework 6

User · Answer

You will have to use the fluent API to do this   Try adding the following to your DbContext   protected override void OnModelCreating DbModelBuilder modelBuilder           modelBuilder Entity lt User gt             HasOptional a   gt  a UserDetail           WithOptionalDependent            WillCascadeOnDelete true

User · Answer

You could also disable the cascade delete convention in global scope of your application by doing this   modelBuilder Conventions Remove lt OneToManyCascadeDeleteConvention gt    modelBuilder Conventions Remove lt ManyToManyCascadeDeleteConvention gt

[c#] Entity Framework (EF) Code First Cascade Delete for One-to-Zero-or-One relationship

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