在变量中创建 if 语句

Question

我正在尝试在下面的代码中创建一个“if”语句：

    var qisg = new QuoteItemSectionGroup
    {
        SectionGroup = db.SectionGroups.Where(x => x.Name == "Longitudinals" && x.Section == TruckSection.Floor).First(),
        StockItem = quoteItem.Chassis.Longitudinal, <<-- Here
        Quantity = 2,
        Length = globals.FloorCalculatedLength
    };

示例：

if (quoteItem.Chassis.Longitudinal == "SCH100")
    Stockitem = quoteItem.BodyType.Longitudinal;

有没有一种方法可以在我的 var qisg 中创建这样的方法？

编辑：这就是代码现在的样子

    var qisg = new QuoteItemSectionGroup
    {
        SectionGroup = db.SectionGroups.Where(x => x.Name == "Longitudinals" && x.Section == TruckSection.Floor).First(),
        StockItem = quoteItem.BodyType.Longitudinal == "SCH100" ? quoteItem.Chassis.Longitudinal : quoteItem.BodyType.Longitudinal,
        Quantity = 2,
        Length = globals.FloorCalculatedLength
    };

我遇到错误：

Operator '==' cannot be applied to operands of type 'TrucksWcf.Models.StockItem' and 'string'

对不起，有些答案有点太复杂了，我看不懂0_o

ALSO 下面是将另一个 StockItem 分配给产品的示例：

    qisg = new QuoteItemSectionGroup
    {
        SectionGroup = db.SectionGroups.Where(x => x.Name == "Cross Member" && x.Section == TruckSection.Floor).First(),
        StockItem = db.StockItems.Where(x => x.StockCode == "SCH075").First(),
        Length = globals.FloorCalculatedWidth
    };

Answer 1

尝试使用条件运算符(https://msdn.microsoft.com/en-us/library/ty67wk28.aspx):

StockItem = quoteItem.Chassis.Longitudinal == "SCH100" ? quoteItem.BodyType.Longitudinal : null,

Answer 2

您可以使用 conditional ternary operator:

The ?: operator can be used as a shortcut for an if...else statement. It is typically used as part of a larger expression where an if...else statement would be awkward.

StockItem = (quoteItem.Chassis.Longitudinal == "SCH100" ?
  quoteItem.BodyType.Longitudinal : null),

表达式的格式，解释：

test ? expression1 : expression2

测试
- 任何布尔表达式。
表达式1
- 如果测试为真则返回一个表达式。可能是一个逗号表达式。
expression2 一个表达式
- 如果测试为假则返回。可能是逗号表达式。

Answer 3

 var qisg = new QuoteItemSectionGroup
    {
        SectionGroup = db.SectionGroups.Where(x => x.Name == "Longitudinals" && x.Section == TruckSection.Floor).First(),
        StockItem = (quoteItem.Chassis.Longitudinal == "SCH100" ? Stockitem = quoteItem.BodyType.Longitudinal : String.Empty),
        Quantity = 2,
        Length = globals.FloorCalculatedLength
    };

Answer 4

正如其他人所说，条件运算符是完美的，如果它是一个简单的 if this..then that... otherwise something else scenario.

如果您的条件更复杂，您可以创建一个方法来检查条件和 returns 适当的值。所以像...

var qisg = new QuoteItemSectionGroup
{
    SectionGroup = db.SectionGroups.Where(somecondition).First(),
    StockItem = DetermineStockItem(valueToCheck)
    Quantity = 2,
    Length = globals.FloorCalculatedLength
};


public StockItem DetermineStockItem(object param)
{
   // Include complex if and logic here.
   return SomeStockItem;
}

编辑： 我刚刚看到您更新的错误消息。看起来 quoteItem.BodyType.Longitudinal 的类型是 StockItem。鉴于你的最后一个代码片段显示 StockItem 有一个 StockCode 我想你可能需要这样的东西......

var qisg = new QuoteItemSectionGroup
{
    SectionGroup = db.SectionGroups.Where(x => x.Name == "Longitudinals" && x.Section == TruckSection.Floor).First(),
    StockItem = quoteItem.BodyType.Longitudinal.StockCode == "SCH100" ? quoteItem.Chassis.Longitudinal : quoteItem.BodyType.Longitudinal,
    Quantity = 2,
    Length = globals.FloorCalculatedLength
};

在变量中创建 if 语句

Creating if statement inside a variable

linq-to-entities