c# - NHibernate QueryOver : How to join unrelated entities?

Question

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？

Answer 1

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();