I want to disable cascade deletes for a link table with entity framework code-first. For example, if many users have many roles, and I try to delete a role, I want that delete to be blocked unless there are no users currently associated with that role. I already remove the cascade delete convention in my OnModelCreating
:
protected override void OnModelCreating(DbModelBuilder modelBuilder) {
...
modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>();
And then I set up the user-role link table:
modelBuilder.Entity<User>()
.HasMany(usr => usr.Roles)
.WithMany(role => role.Users)
.Map(m => {
m.ToTable("UsersRoles");
m.MapLeftKey("UserId");
m.MapRightKey("RoleId");
});
Yet when EF creates the database, it creates a delete cascade for the foreign key relationships, eg.
ALTER TABLE [dbo].[UsersRoles] WITH CHECK ADD CONSTRAINT [FK_dbo.UsersRoles_dbo.User_UserId] FOREIGN KEY([UserId])
REFERENCES [dbo].[User] ([UserId])
ON DELETE CASCADE
GO
ALTER TABLE [dbo].[UsersRoles] WITH CHECK ADD CONSTRAINT [FK_dbo.UsersRoles_dbo.Role_RoleId] FOREIGN KEY([RoleId])
REFERENCES [dbo].[Role] ([RoleId])
ON DELETE CASCADE
GO
How can I stop EF generating this delete cascade?
I got the answer. :-) Those cascade deletes were being created because of ManyToManyCascadeDeleteConvention
. You need to remove this convention to prevent it from creating cascade deletes for link tables:
modelBuilder.Conventions.Remove<ManyToManyCascadeDeleteConvention>();