问题描述
我需要你帮助理解表格之间的关系。我很难理解使用带有外键属性的导航属性来定义关系的用法/需要。 鉴于以下 2 个类,
public class Person
{
[Key,DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid Id { get; set; }
[required]
public string Name{ get; set; }
}
public class Package
{
[Key,DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid Id { get; set; }
[required]
public Guid AccountId { get; set; }
public virtual Person Account { get; set; }
public Guid ShipperId { get; set; }
public virtual Client Shipper { get; set; }
[required]
public Guid ReceiverId { get; set; }
public virtual Client Receiver { get; set; }
}
在表“Packages”上引入 FOREIGN KEY 约束“FK_”可能会导致循环或多个级联路径。指定 ON DELETE NO ACTION 或 ON UPDATE NO ACTION,或修改其他 FOREIGN KEY 约束。
另一方面,如果我删除属性 public Guid ....Id { get; set; }
,数据库将使用外键创建,但 [required]
注释无效。
包含和不包含 Guid
属性有什么区别?
解决方法
尝试使用这些类:
public class Person
{
[Key,DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid Id { get; set; }
[Required]
public string Name{ get; set; }
[InverseProperty(nameof(Package.Account))]
public virtual ICollection<Package> Packages { get; set; }
}
public class Package
{
[Key,DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid Id { get; set; }
[Required]
public Guid AccountId { get; set; }
[ForeignKey(nameof(AccountId))]
[InverseProperty("Packages")]
public virtual Person Account { get; set; }
}
并在 dbcontext 中使用此代码:
modelBuilder.Entity<Package>(entity =>
{
entity.HasOne(d => d.Person)
.WithMany(p => p.Packages)
.HasForeignKey(d => d.AccountId)
.OnDelete(DeleteBehavior.ClientSetNull);
});