加入与逆FK映射的表 [英] Join table in mapping with inverse FK

问题描述

假设我有两张表：

表MY_ENTITY

  ID：PK 
 OTHER_ID：FK表格其他
  

表格其他

  ID：PK 
 COL：我想要
的列 

我的实体看起来像这样：

  class MyEntity：Entity 
 {
 public virtual Column {get;组; } 
} 
  

我的自动映射重写如下所示：

$ b

  mapping.IgnoreProperty（x => x.Column）; 
 mapping.Join（OTHER，x => x.KeyColumn（ID）。Optional（）
 .Map（y => y.Column，COL）; 
  

这工作正常并且执行没有问题，但连接是错误的。

它创建一个SQL语句，将 MY_ENTITY 的PK连接到 KeyColumn 中指定的列 OTHER 。

  select .. 。from MY_ENTITY e left outer join OTHER o on e.ID = o.ID 
  

然而，我需要连接如下：

  select ... from MY_ENTITY e left outer join OTHER o on e.OTHER_ID = o。 ID 
  

如何实现这个功能？

解决方案

您必须添加 OtherId 属性到 MyEntity 不必公开，只是为了映射），并在Join Key中使用 PropertyRef pping（这是通过代码映射的方法名称;它是XML中的 property-ref ，你必须查看Fluent）

或者，map 其他作为实体，并在 MyEntity 中使用 Reference 。您可以级联所有，所以它与MyEntity一起被持续/删除。

然后，只是项目引用属性（这将不会在MyEntity中映射）：

  class MyEntity 
 {
 public virtual PropertyType Property 
 {
 get 
 {
 EnsureOther（）; 
返回Other.Property; 
} 
 set 
 {
 EnsureOther（）; 
 other.Property = value; 
 
 
 
 void EnsureOther（）
 {
 if（Other == null）
 Other = new Other（）; 
} 
 
 public virtual其他{get;组; } 
} 
 
 class其他
 {
 public virtual PropertyType Property {get;组; } 
} 
  

Assume I have two tables:

Table MY_ENTITY

ID: PK
OTHER_ID: FK to table OTHER

Table OTHER

ID: PK
COL: The column I want

My entity looks like this:

class MyEntity : Entity
{
    public virtual Column { get; set; }
}

My auto-mapping override looks like this:

mapping.IgnoreProperty(x => x.Column);
mapping.Join("OTHER", x => x.KeyColumn("ID").Optional()
                            .Map(y => y.Column, "COL");

This works fine and executes without problems, but the join is wrong.

It creates an SQL statement that joins the PK of MY_ENTITY to the column specified in KeyColumn in the table OTHER. Something along the lines of:

select ... from MY_ENTITY e left outer join OTHER o on e.ID = o.ID

However, I need the join to be like this:

select ... from MY_ENTITY e left outer join OTHER o on e.OTHER_ID = o.ID

How to achieve this?

解决方案

You'll have to add an OtherId property to MyEntity (it doesn't have to be public; it's just for mapping) and use PropertyRef in the Join Key mapping (that's the method name in mapping by code; it's property-ref in XML, you'll have to look it up for Fluent)

Alternatively, map Other as an entity and use a Reference in MyEntity. You can cascade all, so it get's persisted/deleted together with MyEntity.

Then, just project the referenced property (which will not be mapped in MyEntity):

class MyEntity
{
    public virtual PropertyType Property
    {
        get
        {
            EnsureOther();
            return Other.Property;
        }
        set
        {
            EnsureOther();
            other.Property = value;
        }
    }

    void EnsureOther()
    {
        if (Other == null)
            Other = new Other();
    }

    public virtual Other { get; set; }
}

class Other
{
    public virtual PropertyType Property { get; set; }
}

这篇关于加入与逆FK映射的表的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！