Question

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我正在尝试使用实际与NHibernate一起使用的组件和EF6。问题是，我有一些TPT继承与不同名称的主键。给出了数据库和POCO类，我无法更改它们，因此CodeFirst和EF设计器都是不可能的。

有没有办法将现有的Db映射到现有的POCO类，就像在NHibernate中使用这些.hbm.xml映射文件一样？

更新

我遇到的实际问题首先是几个类的TPT映射，其中这些类具有不同名称的主键，代码似乎不首先支持。

所以喜欢：

public class Record
{
  public virtual int Ndx { get; set; }  // table column 'ndx'

  public virtual DateTime CreatedAt { get; set; }  // table column 'created'

  // ... further properties
}

public class Patient : Record
{
  public virtual int RecordNdx {get; set;}  // table column 'record_ndx) with FK => records.ndx

  // ... further properties
}

如前所述，更改属性或列名称不是一种选择。

更新II：

这是我的注册码：

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Record>()
        .ToTable("record_descriptors", "schema");

    modelBuilder.Entity<Record>()
        .HasKey<int>(e => e.ndx);

    modelBuilder.Entity<Record>()
        .Property(e => e.read_flag)
        .IsFixedLength()
        .IsUnicode(false);

    modelBuilder.Entity<Record>()
        .Property(e => e.row_version)
        .IsFixedLength();

    modelBuilder.Entity<Record>()
        .Property(e => e.update_info)
        .IsUnicode(false);

    modelBuilder.Entity<Patient>()
        .ToTable("patienten", "schema");

    modelBuilder.Entity<Patient>()
        .Property(e => e.mpi)
        .IsUnicode(false);

    modelBuilder.Entity<Patient>()
        .Property(e => e.ndx)
        .HasColumnName("record_ndx");

    modelBuilder.Entity<Patient>()
        .Ignore(r => r.RecordNdx);
}

更新III

对于测试，我使用：

db.patients.First(p => p.Ndx == 6040);

这会产生以下SQL（由于真实记录和患者类而更广泛）：

SELECT 
    [Limit1].[C1] AS [C1], 
    [Limit1].[ndx] AS [ndx], 
    [Limit1].[owner_user_object_ndx] AS [owner_user_object_ndx], 
    [Limit1].[creator_department_user_object_ndx] AS [creator_department_user_object_ndx], 
    [Limit1].[creator_user_user_object_ndx] AS [creator_user_user_object_ndx], 
    [Limit1].[created] AS [created], 
    [Limit1].[read_flag] AS [read_flag], 
    [Limit1].[last_update] AS [last_update], 
    [Limit1].[last_update_user] AS [last_update_user], 
    [Limit1].[last_update_department] AS [last_update_department], 
    [Limit1].[freitext] AS [freitext], 
    [Limit1].[row_version] AS [row_version], 
    [Limit1].[update_info] AS [update_info], 
    [Limit1].[mpi] AS [mpi]
    FROM ( SELECT TOP (1) 
        [Extent1].[ndx] AS [ndx], 
        [Extent1].[mpi] AS [mpi], 
        [Extent2].[owner_user_object_ndx] AS [owner_user_object_ndx], 
        [Extent2].[creator_department_user_object_ndx] AS [creator_department_user_object_ndx], 
        [Extent2].[creator_user_user_object_ndx] AS [creator_user_user_object_ndx], 
        [Extent2].[created] AS [created], 
        [Extent2].[read_flag] AS [read_flag], 
        [Extent2].[last_update] AS [last_update], 
        [Extent2].[last_update_user] AS [last_update_user], 
        [Extent2].[last_update_department] AS [last_update_department], 
        [Extent2].[freitext] AS [freitext], 
        [Extent2].[row_version] AS [row_version], 
        [Extent2].[update_info] AS [update_info], 
        '0X0X' AS [C1]
        FROM  [schema].[patienten] AS [Extent1]
        INNER JOIN [schema].[record_descriptors] AS [Extent2] ON [Extent1].[ndx] = [Extent2].[ndx]
        WHERE 6040 = [Extent1].[ndx]
    )  AS [Limit1]

这是错误的，因为它从[ndx]中选择[patienten]（必须是record_ndx）并尝试加入[ndx]

Answer 1

关于关闭this work item at CodePlex的说法声称，自从EF 6 定义TPT映射中父和子实体的不同键列名称后，与Code-First一起使用。如果确实如此，则以下Code-First映射应允许映射模型和数据库：

modelBuilder.Entity<Record>() .ToTable("YourRecordTableName"); modelBuilder.Entity<Record>() .HasKey(r => r.Ndx); modelBuilder.Entity<Record>() .Property(r => r.Ndx) .HasColumnName("ndx"); // probably redundant because case doesn't matter modelBuilder.Entity<Record>() .Property(r => r.CreatedAt) .HasColumnName("created"); modelBuilder.Entity<Patient>() .ToTable("YourPatientTableName"); modelBuilder.Entity<Patient>() .Property(r => r.Ndx) // Yes, no typo: It must be Ndx, NOT RecordNdx ! .HasColumnName("record_ndx"); modelBuilder.Entity<Patient>() .Ignore(r => r.RecordNdx);

最后一个映射（忽略RecordNdx属性）很重要。这意味着您的关键属性将为Patient.Ndx。我不认为您可以将派生类中的任何属性作为关键属性。 key属性必须始终位于继承层次结构的基类中。但是，此属性可以映射两次（或者通常在TPT继承链中每个实体一次）到每个表的不同列名 - 从EF 6开始。

完全摆脱RecordNdx属性将是最干净的解决方案。但既然你说你无法触及你的属性，那么将RecordNdx的值与Ndx属性相结合至少是有意义的（如果你可以改变属性getter和setter）：

public virtual int RecordNdx { get { return Ndx; } set { Ndx = value; } }

修改

我刚用EF 6.1测试了上面的Code-First映射，确实有效！ Record表中的主键列为ndx，Patient表中的主键列为record_ndx。在这些之间创建了TPT映射所需的一对一关系。

修改2

这是我使用的完整测试程序（当前的EF 6.1 Nuget包，.NET 4.5，VS 2012，SQL Server 2012 Express）：

using System; using System.Data.Entity; namespace EFTPT6 { public class Record { public virtual int Ndx { get; set; } public virtual DateTime CreatedAt { get; set; } } public class Patient : Record { public virtual int RecordNdx { get; set; } public virtual string Name { get; set; } } public class MyContext : DbContext { public DbSet<Record> Records { get; set; } protected override void OnModelCreating(DbModelBuilder modelBuilder) { modelBuilder.Entity<Record>() .ToTable("Records"); modelBuilder.Entity<Record>() .HasKey(r => r.Ndx); modelBuilder.Entity<Record>() .Property(r => r.Ndx) .HasColumnName("ndx"); modelBuilder.Entity<Record>() .Property(r => r.CreatedAt) .HasColumnName("created"); modelBuilder.Entity<Patient>() .ToTable("Patients"); modelBuilder.Entity<Patient>() .Property(r => r.Ndx) .HasColumnName("record_ndx"); modelBuilder.Entity<Patient>() .Ignore(p => p.RecordNdx); } } class Program { static void Main(string[] args) { Database.SetInitializer(new DropCreateDatabaseAlways<MyContext>()); using (var ctx = new MyContext()) { ctx.Database.Initialize(true); string sql = ctx.Records.ToString(); } } } }

程序末尾的字符串sql是：

SELECT CASE WHEN ( NOT (([Project1].[C1] = 1) AND ([Project1].[C1] IS NOT NULL))) THEN '0X' ELSE '0X0X' END AS [C1], [Extent1].[ndx] AS [ndx], [Extent1].[created] AS [created], CASE WHEN ( NOT (([Project1].[C1] = 1) AND ([Project1].[C1] IS NOT NULL))) THEN CAST(NULL AS varchar(1)) ELSE [Project1].[Name] END AS [C2] FROM [dbo].[Records] AS [Extent1] LEFT OUTER JOIN (SELECT [Extent2].[record_ndx] AS [record_ndx], [Extent2].[Name] AS [Name], cast(1 as bit) AS [C1] FROM [dbo].[Patients] AS [Extent2] ) AS [Project1] ON [Extent1].[ndx] = [Project1].[record_ndx]

看起来映射是受到尊重的，即Records和Patients列由ndx和record_ndx列连接。

编辑3

上下文类不包含派生实体的集合，即无public DbSet<Patient> Patients { get; set; }，这一点非常重要。如果是，则忽略映射modelBuilder.Entity<Patient>().Property(r => r.Ndx).HasColumnName("record_ndx");，并且EF期望Patient中的主键名称为ndx而不是record_ndx。例如，上面SQL中的最后一行变为ON [Extent1].[ndx] = [Project1].[ndx]。

仅将实体框架6中的现有数据库映射到现有的POCO，而无需设计人员或代码优先

1 个答案: