在Hibernate中映射两个相同的表（相同的模式...）到同一个实体 [英] Map Two Identical tables ( same schema...) to same entity in Hibernate

问题描述

我有table1和table2有相同的模式...我想只有一个实体而不是两个（因为字段将是相同的）。
我如何在XML映射的hibernate中实现这一点。
所以我的目标是当我在DAO中查询时，如果两个表映射到同一个实体，它如何知道从哪个表中拉取。

我试图不创建一个父类，然后再创建两个子类。

谢谢

解决方案

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很抱歉，迟到的答案。我在stackoverflow上多次回答了这个问题。

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为了将两个相同的表映射到一个实体类中，您需要使用Hibernate或NHibernate的 entity-name 属性。

文档在这里：
http://docs.jboss.org/hibernate/ core / 3.2 / reference / en / html / mapping.html＃mapping-entityname

例如，要将单个类Order映射到Order和OrderHistory表，您可以使用新的实体名称（ Order 和 OrderHistory ）如下所示：

 < hibernate-mapping xmlns =urn ：NHibernate的映射-2.2\" > 
< class name =DomainModel.Order，DomainModel
 table =Ordersentity-name =Order>`
< id name =_ idaccess =字段column =OrderId> 
< generator class =assigned/> 
< / id> 
< property name = ...> 
< / class> 
< class name =DomainModel.Order，DomainModel
 table =OrderHistoriesentity-name =OrderHistory> 
< id name =_ idaccess =fieldcolumn =OrderId> 
< generator class =assigned/> 
< / id> 
< property name = ...> 
< / class> 
< / hibernate-mapping> 
  

然后根据您需要的实体类型，只需调用相应的Session方法即可：

  _session.Save（Order，myOrder）
  

或

  _session.Save（OrderHistory，myOrder）
  

简单，是不是？

一般 entity-name 必须在所有Hibernate调用中替换类名称。

I have table1 and table2 that have the same schema... and I want to have only one entity rather than two ( since the fields will be the same). How would I achieve that in hibernate with XML mapping. So my goal is when I m querying in the DAO, how would it know which table to pull from if both tables are mapped to the same entity.

I m trying to Not create a parent class and then two subclasses.

Thanks

解决方案

Sorry for the late answer. i have answered this question several times on stackoverflow.

---

To map two identical tables onto one entity class, you need to use the entity-name property of Hibernate or NHibernate.

Documentation is here: http://docs.jboss.org/hibernate/core/3.2/reference/en/html/mapping.html#mapping-entityname

For example, to map a single class Order to Order and OrderHistory tables, you create a mapping file that maps the order class to the two tables using new entity-names (Order and OrderHistory) like this:

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
   <class name="DomainModel.Order, DomainModel"
   table="Orders" entity-name="Order">`  
     <id name="_id" access="field" column="OrderId">
         <generator class="assigned"/>
     </id>
    <property name= ...>
</class>
<class name="DomainModel.Order, DomainModel"
 table="OrderHistories" entity-name="OrderHistory">
     <id name="_id" access="field" column="OrderId">
        <generator class="assigned"/>
     </id>
    <property name= ...>
</class>
</hibernate-mapping>

Then depending on the type of entity you need, you simply call the appropriate Session methods as:

_session.Save("Order", myOrder) 

or

_session.Save("OrderHistory", myOrder)

Simple, isn't ?

In general entity-name must replace class name in all Hibernate calls.

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