NHibernate集合抓取策略

Question

我在fluent api中使用NHibernate，得到的MainEntity映射如下：

mapping.References(c => c.Parent1).Not.Nullable().Fetch.Select();
mapping.HasMany(c => c.Children1).Fetch.Select();
mapping.HasMany(c => c.Children2).Fetch.Select();

然后，我尝试像这样查询MainEntity：

var query = Session.Query<MainEntity>().Where(e => e.ID == id);
query.Fetch(e => e.Parent1).ToFuture();
query.FetchMany(e => e.Children1).ToFuture();
query.FetchMany(e => e.Children2).ThenFetch(c => c.Children21).ToFuture();
var entity = query.ToFuture().FirstOrDefault();

并得到这样的sql查询：

select * from MainEntity
left outer join Parent1 on MainEntity.Parent1ID = Parent1.ID
where MainEntity.ID = @id;

select * from MainEntity
left outer join Children1 on MainEntity.ID = Children1.MainEntityID 
where MainEntity.ID = @id;

select * from MainEntity
left outer join Children2 on MainEntity.ID = Children2.MainEntityID
left outer join Children21 on Children2.Children21ID = Children21.ID
where MainEntity.ID = @id;

select * from MainEntity
where MainEntity.ID = @id;

但我希望NHibernate首先选择MainEntity，然后按条件选择Parent1和Children1，Children2：

select *
from Parent1
where ID = @parent1ID;

select *
from Children1
where MainEntityID = @id;

@parent1ID和@id是通过MainEntities的第一次查询选择的。

请帮助我配置映射以执行此操作。

Answer 1

你有没有尝试过其他LINQ版本？它应该看起来像这样：

Query<Parent>()
.FetchMany(x=>x.Children1)
.FetchMany(x=>x.Children)
.FirstOrDefault(x=>x.Id=param1);

并将子项映射更改为

mapping.HasMany(c => c.Children1);
mapping.HasMany(c => c.Children2);