问题描述
我有一个实体A,其中有许多实体B和实体C.所有实体A,B和C都有一些引用x,y和z,应尽快加载.
I have an entity A which HasMany entities B and entities C. All entities A, B and C have some references x,y and z which should be loaded eagerly.
我想从数据库中读取所有实体A,并使用标准API急切地加载B和C的集合.到目前为止,我已经能够急切地获取"A"中的引用.但是,在加载集合时,它们中的引用会被延迟加载.
I want to read from the database all entities A, and load the collections of B and C eagerly using criteria API.So far, I am able to fetch the references in 'A' eagerly. But when the collections are loaded, the references within them are lazily loaded.
这是我的方法
AllEntities_A =
_session.CreateCriteria(typeof(A))
.SetFetchMode("x", FetchMode.Eager)
.SetFetchMode("y", FetchMode.Eager)
.List<A>().AsQueryable();
使用Fluent的实体A的映射如下所示. _B和_C是B&的私人ILists. C分别在A中.
The mapping of entity A using Fluent is as shown below. _B and _C are private ILists for B & C respectively in A.
Id(c => c.SystemId);
Version(c => c.Version);
References(c => c.x).Cascade.All();
References(c => c.y).Cascade.All();
HasMany<B>(Reveal.Property<A>("_B"))
.AsBag()
.Cascade.AllDeleteOrphan()
.Not.LazyLoad()
.Inverse()
.Cache.ReadWrite().IncludeAll();
HasMany<C>(Reveal.Property<A>("_C"))
.AsBag()
.Cascade.AllDeleteOrphan()
.LazyLoad()
.Inverse()
.Cache.ReadWrite().IncludeAll();
我不想更改映射文件,并且希望尽快加载整个实体A.即我应该得到一个A的列表,其中将有B和C的列表,它们的参考属性也将被急切地加载
I don't want to make changes to the mapping file, and would like to load the entire entity A eagerly. i.e. I should get a List of A's where there will be List of B's and C's whose reference properties will also be loaded eagerly
推荐答案
您正在尝试在此处做笛卡尔乘积.我认为NHibernate要求将关系映射为集合而不是袋,因为袋允许重复.
You're trying to do a cartesian product here. I think NHibernate requires mapping the relations as sets instead of bags to do that, since bags allow duplicates.
无论如何,笛卡尔积是非常低效的.请改用多查询或以后的查询.
Anyway, cartesian products are very inefficient. Use a multi-query or future queries instead.
请参阅:
- Nhibernate:渴望加载两个子集合(一个是组件列表)
- https://nhibernate.jira.com/browse/NH-1471
- http://nhibernate.info/blog/2008/09/06/eager-loading-aggregate-with-many-child-collections.html
- http ://ayende.com/Blog/archive/2010/01/16/eagerly-loading-entity-associations-ficient-with-nhibernate.aspx
- Nhibernate: eager loading two child collections (one being a component list)
- https://nhibernate.jira.com/browse/NH-1471
- http://nhibernate.info/blog/2008/09/06/eager-loading-aggregate-with-many-child-collections.html
- http://ayende.com/Blog/archive/2010/01/16/eagerly-loading-entity-associations-efficiently-with-nhibernate.aspx
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