LINQ check list of objects contain a value AND not some other values

Question

Let's say I have this list of objects:

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 = "32021001004", 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 = "" }
 }
 }
};

I need the query that would check and return only shipment tracking(s) that has trackingCode == "DSP" but not shipment tracking with "CCI" or "POD" trackingCode, so in this example shipment tracking with tracking number 32021001002 would be the one.

I have tried this but doesn't seem to work:

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

Any help or pointer is appreciated. Thanks!

• Caius Jard: t.trackingCode == "DSP" && t.trackingCode != "CCI" - the second predicate is redundant. if TrackingCode equals "DSP" it is automatically not equal to "CCI". You're making a classic mistake of looking (as a human) at values across rows, but writing code that compares values within the same row

Answer 1

You want shipments where for the list of trackings: there IS any tracking code "DSP" and there IS NOT any tracking code "CCI"

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

You could also write this as:

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

i.e. shipments where there is any tracking code that is DSP, and all the tracking codes are not CCI"

Use whichever makes more sense to you

Answer 2

has trackingCode == "DSP" but not shipment tracking with "CCI" or "POD"

I would fill two collections to simplify it and to make it easy to be changed:

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

If you want to ignore the case, so treat dsp and DSP same you need StringComparer.OrdinalIgnoreCase, otherwise StringComparer.Ordinal.

The query is pretty simple:

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();

Instead of two Where you can also use one with &&. I prefer two because it's easier to read.