c# - 带左自连接的 NHibernate QueryOver

Question

我有一个职位表，其中一个职位可以有一个相关职位(但不一定)，每个职位都有一个最后修改日期。然后我想获取在两个给定日期之间修改的所有位置(给定类型)(即修改了“主要”位置或相关位置)。在 SQL 中，我将按如下方式执行此操作:

SELECT * FROM ShipPosition sp
LEFT JOIN ShipPosition sp2 ON sp.RelatedShipPositionID = sp2.ShipPositionID
WHERE sp.ShipPositionTypeID IN (11,12)
AND (sp.ModifiedDate BETWEEN '2011-09-09 08:00' AND '2011-09-09 12:00'
     OR sp2.ModifiedDate BETWEEN '2011-09-09 08:00' AND '2011-09-09 12:00')

现在我对 NHibernate (3.0) 和 QueryOver 还很陌生，我在将此 SQL 查询转换为 C# 代码时遇到了一些问题。我读过一些examples并尝试查看其他问题，但遗憾的是没有运气。

我最初的尝试是这样的:

public IList<ShipPosition> GetModifiedShipPositions(IList<ShipPositionType> positionTypes, DateTime modifiedFrom, DateTime modifiedTo)
{

    var result = Session.QueryOver<ShipPosition>()
        .WhereRestrictionOn(p => p.ShipPositionType).IsInG(positionTypes)
        .And(Restrictions.Or(
            Restrictions.Where<ShipPosition>(p => p.ModifiedDate.IsBetween(modifiedFrom).And(modifiedTo)),
            Restrictions.Where<ShipPosition>(p => p.RelatedShipPosition != null
                                               && p.RelatedShipPosition.ModifiedDate.IsBetween(modifiedFrom).And(modifiedTo))));
    return result.List();
}

但这会抛出 KeyNotFoundException(字典中不存在给定的键)。我已经尝试使用 JoinQueryOver 和 JoinAlias 进行试验，因为我怀疑它是缺少的其中之一，但我没能成功。

如果有人能指出正确的方向(或已回答的问题)，我将不胜感激!

更新:

我尝试使用 linq 编写查询:

var query = Session.Query<ShipPosition>().Where(p
    => positionTypes.Contains(p.ShipPositionType)
    && ((p.ModifiedDate > modifiedFrom && p.ModifiedDate < modifiedTo)
    || (p.RelatedShipPosition != null && p.RelatedShipPosition.ModifiedDate > modifiedFrom && p.RelatedShipPosition.ModifiedDate < modifiedTo)));
return query.ToList();

那没有抛出任何异常，但我没有得到想要的结果(缺少 p.RelatedShipPosition 为 null 的情况。

刚才提到，使用 HQL 工作正常并给出与 SQL 查询相同的结果:

var queryString = @"
        SELECT shipPosition
        FROM ShipPosition shipPosition
        LEFT JOIN shipPosition.ShipPositionType shipPositionType
        LEFT JOIN shipPosition.RelatedShipPosition relatedShipPosition
        WHERE shipPositionType.SystemName IN (:positionTypes)
        AND (shipPosition.ModifiedDate BETWEEN :modifiedFrom AND :modifiedTo
            OR relatedShipPosition.ModifiedDate BETWEEN :modifiedFrom AND :modifiedTo)";

var query = Session.CreateQuery(queryString);
query.SetParameterList("positionTypes", positionTypes.Select(pt => pt.SystemName).ToArray());
query.SetParameter("modifiedFrom", modifiedFrom);
query.SetParameter("modifiedTo", modifiedTo);

return query.List<ShipPosition>();

所以问题仍然存在:如何将其转化为使用 QueryOver？

更新 2:
以防万一有人感兴趣，在 MonkeyCoder 的回答的帮助下，我将包括我的最终代码的样子:

public IList<ShipPosition> GetModifiedShipPositions(DateTime modifiedFrom, DateTime modifiedTo, params ShipPositionType[] positionTypes)
{
    ShipPosition relatedShipPosition = null;

    var result = Session.QueryOver<ShipPosition>()
        .Left.JoinAlias(sp => sp.RelatedShipPosition, () => relatedShipPosition)
        .WhereRestrictionOn(sp => sp.ShipPositionType).IsInG(positionTypes)
        .And(Restrictions.Or(
            Restrictions.Where<ShipPosition>(sp => sp.ModifiedDate.IsBetween(modifiedFrom).And(modifiedTo)),
            Restrictions.Where(() => relatedShipPosition.ModifiedDate.IsBetween(modifiedFrom).And(modifiedTo))));

    return result.List();
}

Answer 1

我不知道你是否已经尝试过这个 - 我无法正确测试它 - 因为我不在我的电脑旁，但我认为你可以给尝试一下:

ShipPosition shipPosition = null;
ShipPositionType shipPositionType = null;
RelatedShipPosition relatedShipPosition = null;

var result = QueryOver.Of<ShipPosition>(() => shipPosition)
    .JoinAlias(() => shipPosition.ShipPositionType, () => shipPositionType)
    .JoinAlias(() => shipPosition.RelatedShipPosition, () => relatedShipPosition)
    .WhereRestrictionOn(() => relatedShipPosition.SystemName).IsInG(positionTypes)
    .And(Restrictions.Or(
        Restrictions.Where(() => shipPosition.ModifiedDate).IsBetween(modifiedFrom).And(modifiedTo)),
        Restrictions.Where(() => relatedShipPosition.ModifiedDate).IsBetween(modifiedFrom).And(modifiedTo));

希望对您有所帮助!