EF6 Code First - 使用不匹配的外键配置一对一关系

Question

我使用 Code First 来定义现有数据库的架构。我遇到的问题是它们在表中的键名不太一致。这适用于一对多关系，因为我可以使用 HasForeignKey() 方法，但似乎没有对应的一对一关系。我的表定义是：

namespace Data.Mappings {

    internal class DocumentTypeConfiguration : EntityTypeConfiguration<Document> {

        public DocumentTypeConfiguration() {
            ToTable("ProsDocs");

            HasKey(m => m.Id);

            Property(m => m.Id)
                .HasColumnName("ProsDocId")
                .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);

            // ---- This is the foreign key ----
            Property(m => m.TypeId)
                .HasColumnName("ProsDocTypeId")
                .HasMaxLength(3);

            HasRequired(d => d.DocType)
                .WithRequiredDependent(dt => dt.Document);
                // I need to specify here that the foreign key is named "DocTypeId" and not "DocType_Id"
        }
    }

    internal class DocTypeTypeConfiguration : EntityTypeConfiguration<DocType> {

        public DocTypeTypeConfiguration() {
            ToTable("DocType");

            HasKey(m => m.Id);

            // ---- This is the "child" end of the foreign key ----
            Property(m => m.Id)
                .HasColumnName("DocTypeId")
                .HasMaxLength(4);

            Property(m => m.FullName)
                .HasColumnName("DocTypeDesc")
                .HasMaxLength(255);

            Property(m => m.Priority)
                .HasColumnName("DocPriority");

            // Or would it be easier to define it here?
//            HasRequired(m => m.Document)
//                .WithRequiredDependent(d => d.DocType);
        }
    }
}

为了明确模型，每个Document都有一个DocType，外键关系为Document.ProsDocTypeId --> DocType.Id。

有没有办法为一对一关系的键定义列名？

编辑：我猜我的架构不清楚。

dbo.DocType
-----------
DocTypeId char(4) (PK)
DocTypeDesc varchar(255)

dbo.ProsDocs
------------
ProsDocId int (PK)
ProsDocTypeId char(4)

基本上，我需要生成的查询如下所示：

SELECT 
    [Extent1].[ProsDocId] AS [ProsDocId], 
    [Extent2].[DocTypeId] AS [DocTypeId]
    FROM  [dbo].[ProsDocs] AS [Extent1]
    LEFT OUTER JOIN [dbo].[DocType] AS [Extent2] ON [Extent1].[ProsDocTypeId] = [Extent2].[DocTypeId]
    WHERE [Extent1].[ProsId] = @EntityKeyValue1

但是相反，因为 EF 假设我想使用主键 (dbo.ProsDocs.ProsDocId) 而不是外键 (dbo.ProsDocs.DocTypeId)，所以它生成的查询是这样的：

SELECT 
    [Extent1].[ProsDocId] AS [ProsDocId], 
    [Extent2].[DocTypeId] AS [DocTypeId]
    FROM  [dbo].[ProsDocs] AS [Extent1]
    LEFT OUTER JOIN [dbo].[DocType] AS [Extent2] ON [Extent1].[ProsDocId] = [Extent2].[ProsDocTypeId]
    WHERE [Extent1].[ProsId] = @EntityKeyValue1

区别就在这里：

理想查询：

LEFT OUTER JOIN [dbo].[DocType] AS [Extent2] ON [Extent1].[ProsDocTypeId] = [Extent2].[DocTypeId]

当前查询：

LEFT OUTER JOIN [dbo].[DocType] AS [Extent2] ON [Extent1].[ProsDocId] = [Extent2].[ProsDocTypeId]

我需要在dbo.ProsDocs.ProsDocTypeId 和dbo.DocType.DocTypeId 之间创建一个一对一的关系。 EF 遇到的问题是它只想使用主键而不是外键来创建关系。如何指定外键的列名，以便每个Document 都只有一个DocType？

Answer 1

如果Document 是主体，DocType 是从属，那么您需要

• 在Document上进行此配置

  HasRequired(d => d.DocType).WithRequiredPrincipal(dt => dt.Document);
  

• 或者DocType上的这个配置

  HasRequired(dt => dt.Document).WithRequiredDependent(d => d.DocType);
  

并从Document 中删除TypeId / ProsDocTypeId 属性，因为主体不能具有依赖的外键ID，除非它不是约束，只是普通列。

更新

实体：

public class Document
{
    public string Id { get; set; }
    // This entity is a principal. It can't have foreign key id to dependent.
    // public string TypeId { get; set; }
    public DocType DocType { get; set; }
}

林克：

db.Documents.Include(d => d.DocType)

查询：

 SELECT
    1 AS [C1],
    [Extent1].[ProsDocId] AS [ProsDocId],
    [Extent2].[DocTypeId] AS [DocTypeId],
    FROM  [dbo].[ProsDocs] AS [Extent1]
    LEFT OUTER JOIN [dbo].[DocType] AS [Extent2] ON [Extent1].[ProsDocId] = [Extent2].[DocTypeId]

更新 2

要实现理想的查询，您需要的关系是一对多的。一个DocType 可以有多个Document。

public class Document
{
    public string Id { get; set; }
    public string TypeId { get; set; }
    public DocType DocType { get; set; }
}
public class DocType
{
    public string Id { get; set; }
    public string FullName { get; set; }
    public string Priority { get; set; }
    public ICollection<Document> Documents { get; set; }
}

Document上的配置。

改变这个：

HasRequired(d => d.DocType).WithRequiredDependent(dt => dt.Document);

进入：

HasRequired(d => d.DocType).WithMany(dt => dt.Documents).HasForeignKey(d => d.TypeId);

林克：

db.Documents.Include(d => d.DocType)

查询：

SELECT
    1 AS [C1],
    [Extent1].[ProsDocId] AS [ProsDocId],
    [Extent1].[ProsDocTypeId] AS [ProsDocTypeId],
    [Extent2].[DocTypeId] AS [DocTypeId],
    FROM  [dbo].[ProsDocs] AS [Extent1]
    INNER JOIN [dbo].[DocType] AS [Extent2] ON [Extent1].[ProsDocTypeId] = [Extent2].DocTypeId]