两个实体之间的代码优先外键

Question

好的，我在这里遗漏了什么，或者这只能通过数据注释来完成吗？

我有一个文档实体模型，它有一个指向添加文档的用户的外键（一对一关系）：

[Table("Documents", Schema = "Configuration")]
public class Document : IPrimaryKey {
    [Key]
    public long Id { get; set; }

    [Required]
    public string OrginalName { get; set; }

    [Required]
    public DocumentTypes DocumentType { get; set; }

    [Required]
    public MIMETypes MIMEType { get; set; }

    [Required]
    public byte[] Data { get; set; }

    [DefaultValue(false)]
    public bool IsPublic { get; set; }

    [Required]
    public DateTimeOffset DateTimeAdded { get; set; }

    [Required]
    public long AddedByUser { get; set; }

    [ForeignKey("AddedByUser")]
    public virtual Details Details { get; set; }
}

然后我有一个用户（详细信息）实体，它可以有一个图像文件（存储在文档实体模型中（none|一对一关系）：

[Table("Details", Schema = "User")]
public class Details : IPrimaryKey {
    [Key]
    public long Id { get; set; }

    [Required]
    public string UserId { get; set; }

    [ForeignKey("UserId")]
    public AppUser User { get; set; }

    [Required]
    public string FirstName { get; set; }

    [Required]
    public string LastName { get; set; }

    [CollectionRequired(MinimumCollectionCount = 1)]
    public ICollection<Address> Addresses { get; set; }

    [CollectionRequired(MinimumCollectionCount = 1)]
    public ICollection<Email> Emails { get; set; }

    [CollectionRequired(MinimumCollectionCount = 1)]
    public ICollection<PhoneNumber> PhoneNumbers { get; set; }

    public ICollection<NotificationHistory> NotificationHistory { get; set; }
    public long TimeZoneId { get; set; }

    public long? ImageId { get; set; }

    [ForeignKey("ImageId")]
    public virtual Document Document { get; set; }

    [ForeignKey("TimeZoneId")]
    public virtual TimeZone TimeZone { get; set; }
}

当我尝试创建迁移时出现此错误：

Unable to determine the principal end of an association between the types 'StACS.PeoplesVoice.DataAccessLayer.EntityModels.User.Details' and 'StACS.PeoplesVoice.DataAccessLayer.EntityModels.Configuration.Document'. The principal end of this association must be explicitly configured using either the relationship fluent API or data annotations.

更新：

虽然仍在研究这个问题，但我做了两处更改并能够解决错误，但这在我的数据库中产生了意外结果。

在我添加的文档实体中：

public virtual ICollection<Details> Details { get; set; }

在我添加的详细信息（用户）实体中：

puflic virtual ICollection<Document> Documents { get; set; }

在我的数据库 Tables 中，我现在在我想要的字段上有外键，但我分别有一个辅助外键。

我试过只删除单个虚拟引用并只留下 ICollection 虚拟引用，现在我根本没有外键。

已更新 （基于 Akash Kava 建议）:

我做了以下修改 [Table("Documents", 架构 = "Configuration")] public class 文档：IPrimaryKey { [必需的] public string OrginalName { get;放; }

    [Required]
    public DocumentTypes DocumentType { get; set; }

    [Required]
    public MIMETypes MIMEType { get; set; }

    [Required]
    public byte[] DocumentData { get; set; }

    [DefaultValue(false)]
    public bool IsPublic { get; set; }

    [Required]
    public DateTimeOffset DateTimeAdded { get; set; }

    [Required]
    public long AddedByUser { get; set; }

    [Key]
    public long Id { get; set; }

    [ForeignKey("AddedByUser")]

    [InverseProperty("Image")]

    public virtual Details User { get; set; }
}

[Table("Details", Schema = "User")]
public class Details : IPrimaryKey {
    [Required]
    public string UserId { get; set; }

    [ForeignKey("UserId")]
    public AppUser User { get; set; }

    [Required]
    public string FirstName { get; set; }

    [Required]
    public string LastName { get; set; }

    [CollectionRequired(MinimumCollectionCount = 1)]
    public ICollection<Address> Addresses { get; set; }

    [CollectionRequired(MinimumCollectionCount = 1)]
    public ICollection<Email> Emails { get; set; }

    [CollectionRequired(MinimumCollectionCount = 1)]
    public ICollection<PhoneNumber> PhoneNumbers { get; set; }

    public ICollection<NotificationHistory> NotificationHistory { get; set; }
    public long TimeZoneId { get; set; }
    public long? ImageId { get; set; }

    [ForeignKey("ImageId")]
    [InverseProperty("User")]
    public Document Image { get; set; } 

    [ForeignKey("TimeZoneId")]
    public virtual TimeZone TimeZone { get; set; }


    [Key]
    public long Id { get; set; }
}

我注释掉了 Fluent API 代码

Unable to determine the principal end of an association between the types 'StACS.PeoplesVoice.DataAccessLayer.EntityModels.User.Details' and 'StACS.PeoplesVoice.DataAccessLayer.EntityModels.Configuration.Document'. The principal end of this association must be explicitly configured using either the relationship fluent API or data annotations.

Answer 1

好的，我终于明白了。遗憾的是，这不是很直接，因为我认为数据注释应该可以工作，但事实并非如此。

你必须使用 Fluent API:

        modelBuilder.Entity<Details>()
                    .HasOptional(x => x.Document)
                    .WithMany()
                    .HasForeignKey(x => x.ImageId);

        modelBuilder.Entity<Document>()
                    .HasRequired(x => x.User)
                    .WithMany()
                    .HasForeignKey(x => x.AddedByUser);

Answer 2

您也可以使用数据注释实现相同的效果，您缺少 InverseProperty 属性，它解决了这种情况下的歧义。从概念上讲，每个导航属性都有反向导航属性，EF 会根据类型自动检测并假定反向属性，但是如果两个实体通过多个 FK 属性相互关联，则必须在相应的导航属性上明确指定 InverseProperty 属性。

我建议在每个导航上放置 InverseProperty 属性，这有助于减少 EF 的启动时间，因为 EF 不必确定和验证模型。

示例，

public class AccountEmail {

    public long AccountID {get;set;}

    // Inverse property inside Account class
    // which corresponds to other end of this
    // relation
    [InverseProperty("AccountEmails")]
    [ForeignKey("AccountID")]
    public Account Account {get;set;}

}

public class Account{

    // Inverse property inside AccountEmail class
    // which corresponds to other end of this
    // relation
    [InverseProperty("Account")]
    public ICollection<AccountEmail> AccountEmails {get;set;}
}

我编写了一个文本模板，它根据当前架构生成所有这些导航属性。从 https://github.com/neurospeech/atoms-mvc.net/tree/master/db-context-tt 下载所有三个文件，您可能需要对其进行自定义，因为它会根据我们的框架添加更多内容，但它会直接从您的数据库生成纯代码模型。

两个实体之间的代码优先外键

Code First Foreign Keys between two entities

c#

entity-framework

data-annotations

ef-fluent-api