c#之NHibernate QueryOver : How to join unrelated entities

我有以下查询可以得到我想要的结果:

int associatedId = 123; 
 
MyObject alias = null; 
 
var subQuery = QueryOver.Of<DatabaseView>() 
    .Where(view => view.AssociatedId == associatedId) 
    .And(view => view.ObjectId == alias.ObjectId) 
    .Select(view => view.ObjectId); 
 
var results = session.QueryOver<MyObject>(() => alias) 
    .WithSubquery.WhereExists(subQuery) 
    .List(); 

DatabaseView已被映射为实际的 NHibernate 实体(因此我可以将它与 QueryOver 一起使用)，但它不与 MyObject 关联。在 HBM 映射中。

此查询返回 IList<MyObject>使用SELECT ... FROM MyObject WHERE EXISTS (subquery for DatabaseView here) 。我如何重写它以返回相同的数据但使用 JOIN 而不是子查询？

请您参考如下方法:

在 NHibernate 5.1+ 中，可以通过 Entity Join 进行 QueryOver/Criteria :

int associatedId = 123; 
 
MyObject alias = null; 
DatabaseView viewAlias = null; 
 
var results = session.QueryOver<MyObject>(() => alias) 
    .JoinEntityAlias(() => viewAlias, () => viewAlias.ObjectId == alias.ObjectId && viewAlias.AssociatedId == associatedId) 
    .List(); 

标准示例:

int associatedId = 123; 
var results = session.CreateCriteria<MyObject>("alias") 
    .CreateEntityAlias( 
            "viewAlias", 
            Restrictions.EqProperty("viewAlias.ObjectId", "alias.ObjectId") 
            && Restrictions.Eq("viewAlias.AssociationId", associatedId), 
            JoinType.InnerJoin, 
            typeof(DatabaseView).FullName) 
    .List();