密钥列具有不同名称时的实体拆分 [英] Entity splitting when key column has different names?

问题描述

我正在使用Entity Framework 4.3.1 Code-First，我需要在两个表之间拆分一个实体。这些表有一个主键共享，它是1对1，但是列在每个表上不相同。

I'm using Entity Framework 4.3.1 Code-First and I need to split an entity between two tables. The tables have a primary key shared, and it is 1-to-1, but the columns are not named the same on each table.

我不控制数据布局，也不能请求任何更改。

I don't control the data layout, nor can I request any changes.

所以例如，SQL表可能是

So for example, the SQL tables could be

< img src =https://i.stack.imgur.com/p0UVF.pngalt =SQL数据表>

这将是我的实体。 ..

And this would be my entity...

public class MyEntity
{
    public int Id {get; set;}
    public string Name {get;set}
    public string FromAnotherTable {get;set;}
}

这里是我的映射。

public class MyEntityMapping : EntityTypeConfiguration<MyEntity>
{
    public MyEntityMapping()
    {
        this.Property(e => e.Id).HasColumnName("ThePrimaryKeyId");
        this.Property(e => e.Name).HasColumnName("MyDatabaseName");
        this.Property(e => e.FromAnothertable).HasColumnName("AnotherTableColumn");
        this.Map(m =>
            {
                m.Properties(e =>
                     {
                         e.Id,
                         e.Name
                     });
                m.ToTable("MainTable");
            });
        this.Map(m =>
            {
                m.Properties(e =>
                     {
                         e.Id,
                         e.FromAnotherTable
                     });
                m.ToTable("ExtendedTable");
            });
}

由于他们之间共享的密钥有不同的列名，我不是肯定如何映射它。该映射将编译，但在运行时失败，因为EF发出SQL查找ExtendedTable表中不存在的ThePrimaryKeyId列。

Since the key shared between them has a different column name, I'm not sure how to map it. This mapping will compile, but fails at runtime because EF emits SQL looking for the "ThePrimaryKeyId" column on the "ExtendedTable" table, which doesn't exist.

编辑
为了澄清，如果PK上的ExtendedTable遵循命名约定，上面所定义的内容可以（也可以）工作。但是它不是，我不能改变模式。

EDIT To clarify, what I have defined above can (and does) work if the PK on the "ExtendedTable" followed naming conventions. But it doesn't and I can't change the schema.

基本上，我需要EF发出的是一个SQL语句，如

Basically, what I need EF to emit is a SQL statement like

SELECT
    [e1].*,   /*yes, wildcards are bad. doing it here for brevity*/
    [e2].*
FROM [MainTable] AS [e1]
INNER JOIN [ExtendedTable] AS [e2]  /*Could be left join, don't care. */
    ON  [e1].[ThePrimaryKeyId] = [e2].[NotTheSameName]

但是，似乎想要排放的是

But the only thing it seems to want to emit is

 SELECT
        [e1].*,
        [e2].*
    FROM [MainTable] AS [e1]
    INNER JOIN [ExtendedTable] AS [e2]
        ON  [e1].[ThePrimaryKeyId] = [e2].[ThePrimaryKeyId] /* this column doesn't exist */

修改
我在NSGaga的建议下再次尝试了1对1的方法。它没有工作，但这里是结果。
实体

Edit I tried the 1-to-1 approach again at NSGaga's suggestion. It didn't work, but here are the results. Entities

public class MyEntity
{
    public int Id { get; set; }
    public int Name { get; set; }
    public virtual ExtEntity ExtendedProperties { get; set; }
}
public class ExtEntity
{
    public int Id { get; set; }
    public string AnotherTableColumn { get; set; }
    public virtual MyEntity MainEntry { get; set; }
}

以下是映射类

public class MyEntityMapping : EntityTypeConfiguration<MyEntity>
{
    public MyEntityMapping()
    {
        this.Property(e => e.Id).HasColumnName("ThePrimaryKeyId");
        this.Property(e => e.Name).HasColumnName("MyDatabaseName");
        this.ToTable("MainTable");
        this.HasKey(e => e.Id);
        this.HasRequired(e => e.ExtendedProperties).WithRequiredPrincipal(f => f.MainEntry);
    }
}

public class ExtEntityMapping : EntityTypeConfiguration<ExtEntity>
{
    public ExtEntityMapping()
    {
        this.Property(e => e.Id).HasColumnName("NotTheSameName");
        this.Property(e => e.AnotherTableColumn).HasColumnName("AnotherTableColumn");
        this.ToTable("ExtendedTable");
        this.HasKey(e => e.Id);
        this.HasRequired(e => e.MainEntry).WithRequiredDependent(f => f.ExtendedProperties);
    }
}

此设置获取消息

"Column or attribute 'MyEntity_ThePrimaryKeyId' is not defined in 'ExtendedTable'"

将最终的地图行更改为

this.HasRequired(e => e.MainEntry).WithRequiredDependent(f => f.ExtendedProperties).Map(m => M.MapKey("NotTheSameName"));

返回此消息

"Each property name in a type must be unique. property name 'NotTheSameName' was already defined."

更改映射键以使用父表格中的列， MapKey（ ThePrimaryKeyId）。返回此消息

Changing the mapped key to use the column from the parent table, MapKey("ThePrimaryKeyId"). returns this message

"Column or attribute 'ThePrimaryKeyId' is not defined in 'ExtendedTable'"

从 ExtEntity ID c $ c> class抛出一个错误，因为实体没有定义的键。

Removing the Id property from the ExtEntity class throws an error because then the entity doesn't have a defined key.

推荐答案

我找不到任何具体说明列的名称必须在两个表中都是相同的;但是我也不能找到任何不说的内​​容，也不能解释如何映射这种情况。我可以找到的每个例子都有两个表中相同名字的键。它看起来像是DbContext设计中的一个洞。

I can't find anything that specifically states that the name of the column has to be the same in both tables; but neither can I find anything that says it doesn't, or explains how you would map that scenario. Every example I can find has the key with the same name in both tables. It looks to me like this is a hole in the DbContext design.

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