NHibernate属性映射:列和公式 [英] NHibernate property mapping: columns and formula
问题描述
当我映射检查表中的列时,我会这样做:
When i map columns from the inspected table, i do this:
<property name="InstanceName" type="MyNameUserType, MyApp.MyNamespace">
<column name="Name"/>
<column name="Name2"/>
</property>
如何使属性映射使用由公式的sql查询检索的数据初始化UserType?
How can I make property mapping initialize a UserType with data retrieved by the formula's sql query?
<property name="InstanceName" type="MyNameUserType, MyApp.MyNamespace" formula="(...)"/>
失败,但出现列数错误"的错误.
fails with an exception "wrong number of columns".
提前谢谢!
推荐答案
我是Michael所引用文章的作者.我不知道人们仍然对它感兴趣,并且我不确定它是否适用于最新的NHibernate. 不过,这里有一个新的链接: http://thoughtspam.wordpress .com/2007/12/19/nhibernate-property-with-formula/
I'm the author of the articles referenced by Michael. I had no idea people where still interested and I'm not sure it's applicable with the latest NHibernate. Here's a fresh link though: http://thoughtspam.wordpress.com/2007/12/19/nhibernate-property-with-formula/
示例,使用罗斯文(Northwind)...
example, using Northwind...
映射:
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
<class name="PropertyFormulaExample.Shipper, PropertyFormulaExample" table="Shippers" lazy="false" >
<id name="ShipperID" column="ShipperID" unsaved-value="0">
<generator class="native" />
</id>
<property name="CompanyName" column="CompanyName" />
<property name="Phone" column="Phone" />
</class>
</hibernate-mapping>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
<class name="PropertyFormulaExample.Order, PropertyFormulaExample" table="Orders" lazy="false">
<id name="OrderID" column="OrderID" unsaved-value="0">
<generator class="native" />
</id>
<property name="CustomerID" column="CustomerID" />
<property name="ShipVia" type="PropertyFormulaExample.Shipper, PropertyFormulaExample" formula="dbo.GetShipper(shipvia)" />
</class>
</hibernate-mapping>
实体:
public class Order
{
public int OrderID { get; set; }
public string CustomerID { get; set; }
public Shipper ShipVia { get; set; }
}
public class Shipper : ILifecycle
{
public int ShipperID { get; set; }
public string CompanyName { get; set; }
public string Phone { get; set; }
#region ILifecycle Members
public LifecycleVeto OnDelete(NHibernate.ISession s)
{
throw new NotImplementedException();
}
public void OnLoad(NHibernate.ISession s, object id)
{
}
public LifecycleVeto OnSave(NHibernate.ISession s)
{
throw new NotImplementedException();
}
public LifecycleVeto OnUpdate(NHibernate.ISession s)
{
throw new NotImplementedException();
}
#endregion
}
最后是SQL函数:
CREATE FUNCTION dbo.GetShipper(@shipperId int)
RETURNS int
AS
BEGIN
RETURN @shipperId
END
显然,您希望函数执行有意义的事情,但是您的想法是返回实体的PK并实现ILifecycle.
Obviously, you’ll want the function to do something meaningful, but the idea is you return the PK for the entity and implement ILifecycle.
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