c# – 无法确定外键的复合外键排序

发布时间：2020-12-15 23:48:45 所属栏目：百科来源：网络整理

导读：Person是包含所有用户的用户模型.更改模型包括EngineerId和ManagerId,两者都是Person ID.为什么我收到此错误？ Unable to determine a composite foreign key ordering for foreign key on type ProjectName.Models.Change. When using the ForeignKey data

Person是包含所有用户的用户模型.更改模型包括EngineerId和ManagerId,两者都是Person ID.为什么我收到此错误？

Unable to determine a composite foreign key ordering for foreign key on type ProjectName.Models.Change. When using the ForeignKey data annotation on composite foreign key properties ensure order is specified by using the Column data annotation or the fluent API.

public class Change
{
    [Key]
    public int ChangeId { get; set; }

    [Required(ErrorMessage = "Change description is required.")]
    [Display(Name = "Change Description")]
    [DataType(DataType.MultilineText)]
    public string ChangeDescription { get; set; }

    [Required(ErrorMessage = "Change date is required.")]
    [Display(Name = "Date of Change")]
    [DataType(DataType.Date)]
    public DateTime ChangeDate { get; set; }

    [Required(ErrorMessage = "Time is required.")]
    [Display(Name = "Time of Change")]
    [DataType(DataType.Time)]
    public DateTime ChangeTime { get; set; }

    [Required(ErrorMessage = "Engineer name is required.")]
    [Display(Name = "Engineer")]
    [ForeignKey("person")]
    public int EngineerId { get; set; }

    [Required(ErrorMessage = "Status is required.")]
    [Display(Name = "Status")]
    public int StatusId { get; set; }

    [Required(ErrorMessage = "Manager is required.")]
    [Display(Name = "Manager")]
    [ForeignKey("person")]
    public int ManagerId { get; set; }

    [Required(ErrorMessage = "System is required.")]
    [Display(Name = "System")]        
    public int SystemDetailId { get; set; }

    public virtual Person person { get; set; }
    public virtual Status status { get; set; }
    public virtual SystemDetail systemdetail { get; set; }
}

解决方法

您有2个外键属性(EngineerId和ManagerId),它们(通过ForeignKey属性)与同一个导航属性(person)相关联.这种方式EF认为它们形成一个复合键,因此你得到的例外.

由于(如果我理解正确)你的意图是有两个关系,你需要将每个外键与一个单独的导航属性相关联.以下是您需要更改的重要部分：

public class Change
{
    // ...

    [Required(ErrorMessage = "Engineer name is required.")]
    [Display(Name = "Engineer")]
    [ForeignKey("Engineer")]
    public int EngineerId { get; set; }

    [Required(ErrorMessage = "Manager is required.")]
    [Display(Name = "Manager")]
    [ForeignKey("Manager")]
    public int ManagerId { get; set; }

    // instead of person property:
    public virtual Person Engineer { get; set; }
    public virtual Person Manager { get; set; }
}

（编辑：李大同）

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