我试图用NHibernate
表达以下SQL查询DECLARE @date DATETIME = NULL;
SELECT
ER.Id
, ER.DocumentDate
FROM
ExpenseReport ER
WHERE
ER.PeriodFrom >= COALESCE(@date, ER.PeriodFrom)
OR ER.PeriodTo <= COALESCE(@date, ER.PeriodTo);
所以,在C#部分,我确实有以下类:
代码段:
// ----- Entity class.
public partial class ExpenseReport
{
public Nullable<System.DateTime> PeriodFrom { get; set; }
// many other properties
}
// ----- Search parameter class.
public class SearchParameters
{
public Nullable<System.DateTime> DateFrom { get; set; }
// many other properties
}
因此,现在将搜索参数分配给IQueryOver<ExpenseReport>
var q = SessionProvider.QueryOver<ExpenseReport>();
现在我对NHibernate感到有点迷茫....我现在该怎么做?
q.And( /*** I AM STUCK HERE **/)
答案 0 :(得分:4)
草稿代码应如下所示:
// left side
var left = Projections.Property<ExpenseReport>(ti => ti.PeriodFrom);
// right side
var right = Projections.SqlFunction("COALESCE"
, NHibernateUtil.DateTime
, Projections.Constant(search.DateFrom, NHibernateUtil.DateTime)
, Projections.Property<ExpenseReport>(ti => ti.PeriodFrom)
);
// the restriction using the GeProperty, taking two IProjections
var restriction = Restrictions.GeProperty(left, right);
// finally - our query get its WHERE
q.Where(restriction);
因此,我们首先创建两个预测。然后我们使用Restrictions
实用程序集来创建>=
(GeProperty)。最终的限制最终传递到WHERE子句......