LINQ 检查对象列表包含一个值而不是其他一些值

Question

假设我有这个对象列表：

var shipments = new List<ShipmentTracking>() {
    new ShipmentTracking() {
        trackingNumber = "32021001000", trackings = new List<Tracking>() {
            new Tracking() { trackingCode = "EBC", trackingPoint = "Entered", trackingDateTime = DateTime.Now, trackingMemo = "" }
        }
    },
    new ShipmentTracking() {
        trackingNumber = "32021001001", trackings = new List<Tracking>() {
            new Tracking() { trackingCode = "EBC", trackingPoint = "Entered", trackingDateTime = DateTime.Now.AddDays(1), trackingMemo = "" },
            new Tracking() { trackingCode = "AWB", trackingPoint = "Registered", trackingDateTime = DateTime.Now.AddDays(1), trackingMemo = "" }
        }
    },
    new ShipmentTracking() {
        trackingNumber = "32021001002", trackings = new List<Tracking>() {
            new Tracking() { trackingCode = "EBC", trackingPoint = "Entered", trackingDateTime = DateTime.Now.AddDays(2), trackingMemo = "" },
            new Tracking() { trackingCode = "AWB", trackingPoint = "Registered", trackingDateTime = DateTime.Now.AddDays(2), trackingMemo = "" },
            new Tracking() { trackingCode = "DSP", trackingPoint = "Shipped", trackingDateTime = DateTime.Now.AddDays(2), trackingMemo = "" }
        }
    },
    new ShipmentTracking() {
        trackingNumber = "32021001003", trackings = new List<Tracking>() {
            new Tracking() { trackingCode = "EBC", trackingPoint = "Entered", trackingDateTime = DateTime.Now.AddDays(3), trackingMemo = "" },
            new Tracking() { trackingCode = "AWB", trackingPoint = "Registered", trackingDateTime = DateTime.Now.AddDays(3), trackingMemo = "" },
            new Tracking() { trackingCode = "DSP", trackingPoint = "Shipped", trackingDateTime = DateTime.Now.AddDays(3), trackingMemo = "" },
            new Tracking() { trackingCode = "CCI", trackingPoint = "Cleared", trackingDateTime = DateTime.Now.AddDays(3), trackingMemo = "" }
        }
    },
    new ShipmentTracking() {
        trackingNumber = "32021001003", trackings = new List<Tracking>() {
            new Tracking() { trackingCode = "EBC", trackingPoint = "Entered", trackingDateTime = DateTime.Now.AddDays(4), trackingMemo = "" },
            new Tracking() { trackingCode = "AWB", trackingPoint = "Registered", trackingDateTime = DateTime.Now.AddDays(4), trackingMemo = "" },
            new Tracking() { trackingCode = "DSP", trackingPoint = "Shipped", trackingDateTime = DateTime.Now.AddDays(4), trackingMemo = "" },
            new Tracking() { trackingCode = "CCI", trackingPoint = "Cleared", trackingDateTime = DateTime.Now.AddDays(4), trackingMemo = "" },
            new Tracking() { trackingCode = "POD", trackingPoint = "Delivered", trackingDateTime = DateTime.Now.AddDays(4), trackingMemo = "" }
        }
    }
};

我需要的查询将检查并仅返回具有 trackingCode == "DSP" 但不使用 "CCI" 或 "POD" trackingCode 的货件跟踪的货件跟踪，因此在此示例中，跟踪号为 32021001002 的货件跟踪将是一。

我已经尝试过了，但似乎不起作用：

foreach (var shipment in shipments)
{
    var foo = shipment.trackings.FirstOrDefault((t => t.trackingCode == "DSP" && t.trackingCode != "CCI"));

    if (shipment.trackings.Contains(foo))
    {
        
    }
}

任何帮助或指针表示赞赏。 谢谢！

Answer 1

您想要在哪里提供跟踪列表：有任何跟踪代码“DSP”并且没有任何跟踪代码“CCI”

shipments.Where(s => 
  s.Trackings.Any(t => t.TrackingCode == "DSP") && 
  !s.Trackings.Any(t => t.TrackingCode == "CCI")
);

你也可以这样写：

shipments.Where(s => 
  s.Trackings.Any(t => t.TrackingCode == "DSP") && 
  s.Trackings.All(t => t.TrackingCode != "CCI")
);

即有任何跟踪代码是 DSP 并且所有跟踪代码都不是 CCI 的货物”

使用对您更有意义的

Answer 2

有 trackingCode == "DSP" 但没有带有 "CCI" 或 "POD" 的货物跟踪

我将填充两个 collections 以简化它并使其易于更改：

var validCodes = new List<string>{"DSP"};
var invalidCodes = new List<string>{"CCI", "POD"};

如果您想忽略这种情况，那么将dsp和DSP视为相同，您需要StringComparer.OrdinalIgnoreCase ，否则StringComparer.Ordinal 。

查询非常简单：

List<ShipmentTracking> trackingList = shipments
    .Where(st => st.trackings.Any(t => validCodes.Contains(t.trackingCode, StringComparer.OrdinalIgnoreCase)))
    .Where(st => !st.trackings.Any(t => invalidCodes.Contains(t.trackingCode, StringComparer.OrdinalIgnoreCase)))
    .ToList();

而不是两个Where你也可以使用一个&& 。 我更喜欢两个，因为它更容易阅读。