NHibernate.用2个查询加载实体并合并 [英] NHibernate. Load Entity with 2 query and merge

问题描述

我有一个复杂的实体，其中包含许多子对象，这些对象也很复杂:

I've got complex entity with a lot of children collection of objects, which are complex too:

public class Order : AdvancedBaseOrder, ICheckable
{
    public virtual ICollection<RouteUnit> RouteUnits
    public virtual ICollection<Invoice> Invoices
    public virtual ICollection<Call> Calls;
    public virtual ICollection<Payment> Payments;
    ......
}

我的付款类别还汇总了许多其他对象

My payment class aggregates a lot of other objects

public class Payment:  ICheckable
{
    public virtual A A;
    public virtual B B;
    public virtual C C;
    public virtual D D;
    ......
}

我想通过2个查询获得订单:

I want get order with 2 queries:

1. 无需付款即可加载订单实体(FetchMode.Lazy)
2. 通过加入其对象的订单加载付款
3. 合并\合并订单及其付款

我不希望nhib进行延迟加载付款，因为我想覆盖付款对象的提取策略.

I don't want lazy load payments by nhib, cause I would like override fetch strategies for payment's objects.

所以我的问题是如何将两个查询结果合并为一个聚合 .谢谢

So my question is how can i merge combine two result of queries in one aggregate . Thanks

推荐答案

在这种情况下，batch-size="25"设置可以为您完成这项工作.在文档中了解更多信息: 19.1.5.使用批量提取.

In this case, batch-size="25" setting could do the job for you. Read more in the documentation: 19.1.5. Using batch fetching.

批处理大小可以应用于 class 或 collection 映射:

batch size coulde be applied on a class or collection maping:

付款类别

<class name="Payment" batch-size="10">...</class>

收款

<class name="Order">
    <set name="Payments" batch-size="3">
        ...
    </set>
</class>

简而言之，批处理的工作方式:NHibernates加载所有Orders的集合.然后根据批量大小设置(例如25)创建对由刚刚加载的 Orders 的ID过滤的Payments的少量调用:

How the batching works in a nutshell: NHibernates loads the set of all Orders. Then based on a batch-size setting (e.g. 25) creates few calls to Payments filtered by IDs of just loaded Orders:

(@ o1，@ o2，@ O3 ... @ o25)中的OrderId在哪里

WHERE OrderId in (@o1, @o2, @O3... @o25)

合并将在NHibernate会话中为您完成.根据我的经验，这是最强大的映射.批处理.

The merge will be done for you inside NHibernate session. From my experience this is most powerful mapping... Lazy & Batching.

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