如何使用EF CTP5 Fluent API在一对多关系中关闭级联删除

Question

在Fluent NHibernate中,您可以为映射设置级联设置,例如

public class StoreMap : ClassMap<Store>
{
  public StoreMap()
  {
    Id(x => x.Id);
    Map(x => x.Name);
    HasMany(x => x.Staff)
      .Inverse()
      .Cascade.None();
    HasManyToMany(x => x.Products)
     .Cascade.All()
     .Table("StoreProduct");
  }
}

如何在实体框架"Code First"中完成这项工作？

Answer 1

如果模型中有一对多关系,则EF代码首先将默认启用级联删除约定.所以你真的不需要做任何特别的事情,但让我们考虑一个你想要覆盖约定并关闭级联删除的场景.这就是今天早些时候EF CTP5附带的Fluent API的完成方式:

public class Customer
{
    public int CustomerId { get; set; }        
    public virtual ICollection<Order> Orders { get; set; }
}

public class Order
{
    public int OrderId { get; set; }
    public int CustomerId { get; set; }        
    public virtual Customer Customer { get; set; }        
}

public class StackoverflowContext : DbContext
{
    public DbSet<Customer> Customers { get; set; }
    public DbSet<Order> Orders { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Customer>()
                    .HasMany(c => c.Orders)
                    .WithRequired(o => o.Customer)
                    .HasForeignKey(o => o.CustomerId)
                    .WillCascadeOnDelete(false);
    }
}