LINQ to object -- 需要带有 AND 和 OR 条件的 where 子句

Question

我是 LINQ 的菜鸟，我无法构建具有多个条件的 where 子句。基本上我需要类似的东西：

SELECT * 
FROM table
WHERE location = @location AND (unitype = "L" OR unittype = "D")

或者：

SELECT *
FROM table
WHERE location = @location AND unitype IN ("D", "L")

我可以执行 AND 或 OR，但我不知道如何在一个语句中执行这两个操作。我现有的查询如下。它有效，但不受位置限制。我可以成功地按位置和单个单位类型进行限制，但不能同时限制两者。我不确定我是否需要子查询或其他方法——一个正确方向的指针将不胜感激！

gvFixed.ItemsSource = from fs in fixedSystem
//where fs.Owner.Location.ToString() == location && (fs.UnitType == "D" || fs.UnitType == "L")
where fs.UnitType == "D" || fs.UnitType == "L"
group fs by new { fs.Owner.Name } into grouping
select new FixedSystem()
{
    Owner = new SystemOwner() { Name = grouping.Key.Name },
    OnHand = grouping.Sum(fs => fs.OnHand),
    FMC = grouping.Sum(fs => fs.FMC),
    NMCS = grouping.Sum(fs => fs.NMCS),
    NMCM = grouping.Sum(fs => fs.NMCM),
    PMCS = grouping.Sum(fs => fs.PMCS),
    PMCM = grouping.Sum(fs => fs.PMCM),
    FMCPercent = Math.Round(grouping.Average(fs => fs.FMCPercent)),
    ScheduleS = grouping.Sum(fs => fs.ScheduleS),
    ScheduleM = grouping.Sum(fs => fs.ScheduleM),
    ScheduleT = grouping.Sum(fs => fs.ScheduleT)
};

错误全文（查询结果将进入 Telerik 数据网格）：

Unhandled Error in Silverlight Application Code: 4004 
Category: ManagedRuntimeError
Message: System.ArgumentOutOfRangeException: Index was out of range. 
Must be non- negative and less than the size of the collection. 
Parameter name: index 
at System.ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument argument, ExceptionResource resource) 
at System.ThrowHelper.ThrowArgumentOutOfRangeException() 
at System.Collections.Generic.List`1.get_Item(Int32 index) 
at Telerik.Windows.Data.KeyedCollection.get_Item(Int32 index) 
at Telerik.Windows.Data.QueryableCollectionView.InternalGetItemAt(Int32 index) 
at Telerik.Windows.Data.QueryableCollectionView.GetItemAt(Int32 index) 
at Telerik.Windows.Data.DataItemCollection.get_Item(Int32 index) 
at Telerik.Windows.Controls.GridView.GridViewItemContainerGenerator.Generator.GenerateNext(Boolean stopAtRealized, Boolean& isNewlyRealized) 
at Telerik.Windows.Controls.GridView.GridViewItemContainerGenerator.System.Windows.Controls.Primitives.IItemContainerGenerator.GenerateNext(Boolean& isNewlyRealized) 
at Telerik.Windows.Controls.GridView.GridViewVirtualizingPanel.GenerateNextChild(IItemContainerGenerator generator, Int32 childIndex) 
at Telerik.Windows.Controls.GridView.GridViewVirtualizingPanel.MeasureOverride(Size constraint) 
at System.Windows.FrameworkElement.MeasureOverride(IntPtr nativeTarget, Single inWidth, Single inHeight, Single& outWidth, Single& outHeight)

Answer 1

抱歉这么久才回到他身边；办公室的其他项目受到干扰。解决方案如下：

gvFixed.ItemsSource = from fs in fixedSystem
where (fs.UnitType == "D" || fs.UnitType == "L") && fs.Owner.Location.ToString() == item.Name
group fs by fs.FixedType into grouping
select new FixedSystem()
{
    Owner = new SystemOwner(),
    FixedType = grouping.Key,
    OnHand = grouping.Sum(fs => fs.OnHand),
    FMC = grouping.Sum(fs => fs.FMC),
    NMCS = grouping.Sum(fs => fs.NMCS),
    NMCM = grouping.Sum(fs => fs.NMCM),
    PMCS = grouping.Sum(fs => fs.PMCS),
    PMCM = grouping.Sum(fs => fs.PMCM),
    FMCPercent = Math.Round(grouping.Average(fs => fs.FMCPercent)),
    ScheduleS = grouping.Sum(fs => fs.ScheduleS),
    ScheduleM = grouping.Sum(fs => fs.ScheduleM),
    ScheduleT = grouping.Sum(fs => fs.ScheduleT)
};

我必须明确地将固定类型属性放入所选对象中。事后看来这是有道理的，但当我最初编写该语句时，似乎没有必要指定已经定义的属性。