c# - Entity Framework : How to enable cascade delete on one way related entities

Question

有两个实体，如下所示:

public class Business
{
    public int Id {get; set;}

    public File Logo {get; set;}
    public int? LogoId {get; set;}

    public File Video {get; set;}
    public int? Video {get; set;}

    public ICollection<File> Images {get; set;}
}

public class File
{
    // some file props, such as Id, Name, ...
}

业务删除文件如何配置级联删除？请注意，我不需要从 File 到 Business 的任何导航。

更新:

您可能会发现 modelBuilder 配置如下:

        modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>();

        modelBuilder.Entity<Entities.Business>()
            .HasOptional(b => b.Logo)
            .WithOptionalPrincipal()
            .WillCascadeOnDelete();

        modelBuilder.Entity<Entities.Business>()
            .HasOptional(b => b.Video)
            .WithOptionalPrincipal()
            .WillCascadeOnDelete();

        modelBuilder.Entity<Entities.Business>()
            .HasMany(b => b.Images)
            .WithOptional()
            .WillCascadeOnDelete();

这是我遇到的错误:

Introducing FOREIGN KEY constraint 'FK_dbo.Files_dbo.Businesses_Business_Id1' on table 'Files' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints. Could not create constraint

Answer 1

如果你喜欢使用单独的配置类，你可以尝试这样的事情:

  public class BusinessConfiguration : EntityTypeConfiguration<Business>
  {
        public BusinessConfiguration()
        {
            HasMany(x => x.Images).WithOptional().WillCascadeOnDelete();
            HasOptional(x => x.Logo).WithOptional().WillCascadeOnDelete();
            HasOptional(x => x.Video).WithOptional().WillCascadeOnDelete();
        }
  }

当您不在 .WithOptional() 或 .WithRequired() 中传递 lambda 时，意味着另一侧没有导航属性。