Question

我有一个Account表和一个Transaction表，没有从Transaction表到Account表的外键引用＆＃34;遗留原因＆＃34;。 NHibernate Account表的映射XML如下所示：

<class name="Account" table="[tblAccount]" lazy="true">
    <id name="ID" column="ID" type="Int32">
      <generator class="native" />
    </id>
    <version name="NHVersion" column="[NHVersion]" unsaved-value="0" />
    <property name="AccountNumber" column="[AccountNumber]" type="String" not-null="true" length="30" />
    <property name="FormattedAccountNumber" column="[FormattedAccountNumber]" type="String" not-null="true" length="30" />
    <property name="Title" column="[Title]" type="String" not-null="true" length="30" />
    <many-to-one name="AccountCode" column="tblAccountCodeID" class="AccountCode" cascade="none" />
    <one-to-one name="AccountSegment" cascade="all" class="AccountSegment" property-ref="Account" />
    <bag name="Categories" table="tblAccountCategory" lazy="true" inverse="false">
      <key column="tblAccountID" />
      <many-to-many class="Category" column="tblCategoryID" />
    </bag>
</class>

Transaction表的映射XML是：

<class name="Transaction" table="[tblTransaction]" lazy="true">
    <id name="ID" column="ID" type="Int32">
      <generator class="native" />
    </id>
    <version name="NHVersion" column="[NHVersion]" unsaved-value="0" />
    <property name="GLAccount" column="[GLAccount]" type="String" not-null="true" length="30" />
    <property name="Description" column="[Description]" type="String" not-null="true" length="60" />
    <property name="Amount" column="[Amount]" type="Decimal" not-null="true" />
</class>

可以使用GLAccount列查询给定帐户的事务表行。以下SQL有效：

select act.FormattedAccountNumber, act.Title, trn.Date, trn.Amount
from tblAccount act
left join tblTransaction trn on act.AccountNumber = trn.GLAccount
where act.AccountNumber = '011020'

如何定义帐户交易的映射？似乎没有办法为每个表指定列名。也许使用where？我看了question and answer，但它似乎并不适用于我的情况。

Answer 1

NHibernate内置解决方案适用于没有主键的场景：

FROM tblAccount act
LEFT JOIN tblTransaction trn 
 ON act.AccountNumber = trn.GLAccount

这就是property-ref魔法。

<class name="Account" table="[tblAccount]" lazy="true">
   ...
   <!-- THE property -->
   <property name="AccountNumber" column="[AccountNumber]" type="String" not-null="true"/>

   <!-- collection referenced by THE property -->
   <bag name="Transactions" lazy="true" inverse="false">
      <!-- key column of a target table -->
      <!-- property-ref of our table -->
      <key column="GLAccount" property-ref="AccountNumber" />
      <one-to-many class="Transaction" />
   </bag>

这是父母，下面是一个孩子（多对一使用与参考相同的属性）

<class name="Transaction" table="[tblTransaction]" lazy="true">
    ...
    <property name="GLAccount"  column="[GLAccount]" type="String" not-null="true"/>
    <many-to-one name="Account" column="[GLAccount]" property-ref="AccountNumber"  />

5.1.11. many-to-one

...

property-ref 属性仅应用于映射旧数据，其中外键是指除主键之外的关联表的唯一键。这是一个丑陋的关系模型。例如，假设Product类具有唯一的序列号，而不是主键。（unique属性使用SchemaExport工具控制NHibernate的DDL生成。）

没有外键关系的NHibernate映射子集合

1 个答案:

5.1.11. many-to-one