Using SetFetchMode

Question

请原谅我的业余冬眠，但我在下面的场景中抓取时很挣扎。

var query = session.CreateCriteria<Notification>().SetFetchMode("Parameters", FetchMode.Select)
.CreateAlias("Parameters", "p", JoinType.InnerJoin)
.Add(Restrictions.Where<Notification>(x => x.Acknowledged == false));

[一些构建名为npHashes的IList的代码]

query = query.Add(Restrictions.In("p.PairHash", npHashes)).AddOrder(new Order("DateCreated", false));

(枚举)

请注意，我使用SELECT作为预取模式…QueryOver中遗漏的一个选项…和LINQ……还请注意，所获取的表与我连接到的表是相同的。

执行该查询的结果如下:

    SELECT
    this_.Id as Id14_1_,
    this_.Version as Version14_1_,
    this_.Url as Url14_1_,
    this_.DispatchType as Dispatch5_14_1_,
    this_.Acknowledged as Acknowle6_14_1_,
    this_.DateCreated as DateCrea7_14_1_,
    this_.NotificationType as Notifica2_14_1_,
    p1_.Id as Id15_0_,
    p1_.Version as Version15_0_,
    p1_.NotificationId as Notifica3_15_0_,
    p1_.Name as Name15_0_,
    p1_.Value as Value15_0_,
    p1_.PairHash as PairHash15_0_ 
FROM
    Notification this_ 
inner join
    NotificationParameter p1_ 
        on this_.Id=p1_.NotificationId 
WHERE
    this_.Acknowledged = ?p0 
    and p1_.PairHash in (
        ?p1
    ) 
ORDER BY
    this_.DateCreated desc;
?p0 = False [Type: Boolean (0)],
?p1 = 'V3zmXnv12B3AC26xeG10w+bas4U=' [Type: String (28)]

所以第一个问题是出于某种原因NotificationParameter列被包含在选择列表中…它似乎没有做select fetch。这是不好的，因为a)我想要一个选择获取b)获取记录被过滤。抓取不同于连接(作为一个概念)，连接数据上的过滤器不应该(在这种情况下)过滤我获取的内容。

第二个问题当然是SELECT取回没有发生。相反，在第一次访问Notification的Parameters属性时，它们被惰性加载:O

帮忙吗?此外，如果有一种方法来做到这一点使用QueryOver我更喜欢。我注意到我可以去。underlyingcriteria . setfetchmode(....)但是这对获取的内容没有影响

Answer 1

在SQL中，您不能同时过滤和获取所有数据。我对查询还不是很熟悉，但是你应该有个概念。

var subquery = DetachedCriteria.For<Notification>()
    .CreateAlias("Parameters", "p", JoinType.InnerJoin)
    .Add(Restrictions.Where<Notification>(x => x.Acknowledged == false))
    .Add(Restrictions.In("p.PairHash", npHashes))
    .SetProjection(Projections.Id());
session.CreateCriteria<Notification>()
    .Add(Subqueries.PropertyIn("Id", subquery))
    .SetFetchMode("Parameters", FetchMode.Eager)
    .AddOrder(Order.Asc("DateCreated"))
    .List<Notification>();