NHibernate QueryOver 与 JoinQueryOver 选择所有列

Question

我有一些带有多个连接的 QueryOver，就返回的对象而言，我得到的结果是可以的。这是代码>

   var l = session.QueryOver<Discount>(() => discount)
                .JoinQueryOver<ConPrdGrp>(r => r.ConPrdGrps)
                .JoinQueryOver<PrdGroupTree>(k => k.PrdGroupTree)
                .JoinQueryOver<Product>(g => g.Products)
                .Where(p => p.ProductID == Product.ProductID)
                .And(() => discount.FomDato <= DateTime.Now && discount.TomDato >= DateTime.Now).List();

但是如果我查看 SQL 语句，我可以看到生成的查询从所有连接的表中选择所有列，尽管结果只返回 Discount 对象的列表。我可以使用投影获得 Discount 的一些属性，并且查询会小得多。但是我如何指示 NHibernate 只从 Discount 表中获取列而不是从所有连接表中获取列？

Answer 1

据我所知，没有像这样简单的方法:.Select(Projections.Properties<Discount>()) .检查这个有点过时的问题( NHIbernate: Shortcut for projecting all properties? )

您可以做的是明确命名您想要查看的列:

  ... // the QueryOver you have
  .SelectList (l => l
    .Select(() => discount.ID).WithAlias(() => discount.ID)
    .Select(() => discount.Code).WithAlias(() => discount.Code)
    ...
  )
  .TransformUsing(Transformers.AliasToBean<Discount>())
  ...

第二种方法可能是创建子查询，然后只是 QueryOver<Discount>() 16.8. Subqueries

QueryOver<Discount> subQuery =
    QueryOver.Of<Discount>(() => innerDiscount)
      .JoinQueryOver<ConPrdGrp>(r => r.ConPrdGrps)
      .JoinQueryOver<PrdGroupTree>(k => k.PrdGroupTree)
      .JoinQueryOver<Product>(g => g.Products)
      .Where(p => p.ProductID == Product.ProductID)
      .And(() => innerDiscount.FomDato <= DateTime.Now 
              && innerDiscount.TomDato >= DateTime.Now).List()
      .Select( Projections.Property(() => innerDiscount.ID))
 ;

var query = session.QueryOver<Discount>(() => discount)
  .Where(Subqueries.PropertyIn("ID", subQuery.DetachedCriteria))
  ;