无法确定外键的复合外键顺序

问题描述

人员是包括所有用户的用户模型.更改模型包括EngineerId和ManagerId，它们都是Person ID.为什么会出现此错误?

Person is the user model that includes all users. The change model includes the EngineerId and the ManagerId, both are Person IDs. Why am I getting this error?

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; }
}

推荐答案

您具有两个关联的外键属性( EngineerId 和 ManagerId )(通过 ForeignKey 属性)，并具有相同的导航属性( person ).EF通过这种方式认为它们构成了一个复合密钥，因此您将获得异常.

You have 2 foreign key properties (EngineerId and ManagerId) that you have associated (via ForeignKey attribute) with the one and the same navigation property (person). This way EF thinks they form a composite key, hence the exception you are getting.

由于(如果我理解正确)，您的意图是建立2个关系，因此需要将每个外键与单独的导航属性相关联.这是您需要更改的必要部分:

Since (if I understand correctly) your intent is to have 2 relationships, you need to associate each foreign key with a separate navigation property. Here is the essential part that you need to change:

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; }
}

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