Question

我正在将旧式查询CreateCriteria()重构为QueryOver()。我的Wcf服务获取string PropertyName订单查询结果。对于IQueryable我使用动态LINQ对CreateCriteria() - AddOrder()进行此类排序。

IList<object[]> result =
            GetSession()
                .QueryOver(() => activity)
                .JoinAlias(() => activity.ActivityLicense, () => license)
                .Select(Projections.ProjectionList()
                            .Add(Projections.Count<Activity>(e => e.Id), "ActivityCount")
                            .Add(Projections.Group(() => license.SerialNumber), "SerialNumber")
                            .Add(Projections.Count<Activity>(e => e.MacAdress), "MacAddressCount")
                            .Add(Projections.Count<Activity>(e => e.IpAdress), "IpAddressCount")
                )
                .OrderByAlias("ActivityCount") // Compilation Error - I need such extension method
                .List<object[]>();

有关字符串属性名称如何进行排序的任何建议？

PS：我无法使用LINQ到Nhibernate：LINQ to NHibernate - .GroupBy().Skip().Take() cause an exception

谢谢！

Answer 1

您始终可以获得UnderlyingCriteria ...

var q = GetSession()
                .QueryOver(() => activity)
                .JoinAlias(() => activity.ActivityLicense, () => license)
                .Select(Projections.ProjectionList()
                            .Add(Projections.Count<Activity>(e => e.Id), "ActivityCount")
                            .Add(Projections.Group(() => license.SerialNumber), "SerialNumber")
                            .Add(Projections.Count<Activity>(e => e.MacAdress), "MacAddressCount")
                            .Add(Projections.Count<Activity>(e => e.IpAdress), "IpAddressCount")
                );


q.UnderlyingCriteria.AddOrder(new Order("ActivityCount", true));

var results = q.List();

或作为IQueryOver的扩展方法

public static IQueryOver<T,T> OrderByAlias(this IQueryOver<T,T> q, string aliasName, bool ascending)
{
    q.UnderlyingCriteria.AddOrder(new Order(aliasName, ascending));
    return q;
}

Answer 2

您可以通过传入Projections.Property(propName)直接从QueryOver API设置OrderBy，例如：

var query = GetSession()
                .QueryOver<Activity>()
                .OrderBy(Projections.Property("ActivityCount").Desc;

无法通过字符串设置方向，因此您必须执行简单的if / else或创建扩展方法以简化API。

Nhibernate QueryOver。 OrderBy使用字符串属性名称。

2 个答案: