NHibernate Linq 提供程序中的 Fetch 与 FetchMany [英] Fetch vs FetchMany in NHibernate Linq provider

问题描述

NHibernate 预先加载可以使用 Fetch 和 FetchMany 完成，如 NHibernate Linq Eager Fetching 在 Mike Hadlow 的博客上.

NHibernate eager loading can be done using Fetch and FetchMany, as described in NHibernate Linq Eager Fetching on Mike Hadlow's blog.

这两种方法有什么区别，分别在什么情况下使用?

What is the difference between these two methods and under what circumstance would each be used?

推荐答案

Fetch 用于引用，FetchMany 用于集合.

Fetch should be used for references and FetchMany for collections.

这一点特别重要，因为只有 FetchMany 可以与 ThenFetchMany 结合来获取孙子"集合.

This is particularly important because only FetchMany can be combined with ThenFetchMany to fetch "grandchildren" collections.

示例:

session.Query<User>()
       .FetchMany(u => u.Orders)
       .ThenFetchMany(o => o.OrderItems)

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