LINQ 檢查對象列表包含一個值而不是其他一些值

Question

假設我有這個對象列表：

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 = "" }
        }
    }
};

我需要的查詢將檢查並僅返回具有 trackingCode == "DSP" 但不使用 "CCI" 或 "POD" trackingCode 的貨件跟蹤的貨件跟蹤，因此在此示例中，跟蹤號為 32021001002 的貨件跟蹤將是一。

我已經嘗試過了，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))
    {
        
    }
}

任何幫助或指針表示贊賞。 謝謝！

Answer 1

您想要在哪里提供跟蹤列表：有任何跟蹤代碼“DSP”並且沒有任何跟蹤代碼“CCI”

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

你也可以這樣寫：

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

即有任何跟蹤代碼是 DSP 並且所有跟蹤代碼都不是 CCI 的貨物”

使用對您更有意義的

Answer 2

有 trackingCode == "DSP" 但沒有帶有 "CCI" 或 "POD" 的貨物跟蹤

我將填充兩個 collections 以簡化它並使其易於更改：

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

如果您想忽略這種情況，那么將dsp和DSP視為相同，您需要StringComparer.OrdinalIgnoreCase ，否則StringComparer.Ordinal 。

查詢非常簡單：

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();

而不是兩個Where你也可以使用一個&& 。 我更喜歡兩個，因為它更容易閱讀。