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[英]Adding Property to Model in CodeFirst entity framework for an existing column in db
[英]Solely mapping existing db to existing POCOs without designer or CodeFirst in Entity Framework 6
@slauma的一个关键事实发表了评论。 因此,请查看答案和评论!
我正在尝试使用EF6现在与NHibernate实际一起使用的组件。 问题是,我有一些带有不同名称的主键的TPT继承。 给出了数据库和POCO类,我无法更改它们,因此CodeFirst和EF设计器都毫无疑问。
有没有办法像将NHibernate中的这些.hbm.xml映射文件一样,将现有的Db映射到现有的POCO类?
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,似乎代码首先不支持该主键。
像这样:
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。
更新二:
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);
}
更新三
为了测试,我使用:
db.patients.First(p => p.Ndx == 6040);
这将产生以下SQL(由于实际记录和患者类别的原因,其内容更加广泛):
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[patienten]
选择[ndx]
(必须为record_ndx
),并且还尝试加入[ndx]
关于在CodePlex上关闭此工作项的评论声称, 由于EF 6在TPT映射中定义父实体和子实体的不同键列名称,因此可以与Code-First一起使用。 如果是这样,则以下“代码优先”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是Patient.Ndx
。 我认为您不能将派生类中的任何属性设置为关键属性。 key属性必须始终位于继承层次结构的基类中。 但是,从EF 6开始,此属性可以映射两次(或者通常在TPT继承链中每个实体映射一次)到每个表的不同列名。
完全摆脱RecordNdx
属性将是最干净的解决方案。 但是,因为您说过您无法触摸属性,所以至少将RecordNdx
的值RecordNdx
到Ndx
属性是Ndx
( 如果可以更改属性的getter和setter):
public virtual int RecordNdx
{
get { return Ndx; }
set { Ndx = value; }
}
编辑
我刚刚使用EF 6.1测试了上面的Code-First映射,它确实有效! Record
表中的主键列是ndx
,而Patient
表中的主键列是record_ndx
。 在这些EF之间创建TPT映射所需的一对一关系。
编辑2
那是我使用的完整测试程序(当前的EF 6.1 Nuget程序包,.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]
看起来映射已得到遵守,即Records
和Patients
表由ndx
和record_ndx
列连接。
编辑3
重要的是,上下文类不包含派生实体的集合,即没有public DbSet<Patient> Patients { get; set; }
public DbSet<Patient> Patients { get; set; }
public DbSet<Patient> Patients { get; set; }
。 如果这样做,则映射modelBuilder.Entity<Patient>().Property(r => r.Ndx).HasColumnName("record_ndx");
会被忽略,并且EF期望Patient
中的主键名称是ndx
而不是record_ndx
。 例如,上面的SQL中的最后一行变为ON [Extent1].[ndx] = [Project1].[ndx]
。
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