Complex Linq Query

David Smith

I need to write a linq that give me max DetailRoot EventDate Where DetailModel Color equals "Red". Review structure below

Dictionary> dataList = Reporter.GetSiteData();

public class DetailRoot
{

public string UserId{ get; set; }
public string Session{ get; set; }

public Datetime EventDate { get; set; }
public IReadOnlyList DetailList { get; set; }

}

public class DetailModel
{
public string ApplicationGuid { get; set; }
public string ColorType { get; set; }

}

4 Replies

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Simone Cappelletti4y ago
You're right my solution would go into exception if it doesn't find the color red.
So you can take the other solution from Mario or if you want a default value in case red color is not present you can do something like:

var query = from source in dataList.AsEnumerable()
                 let x = source.Value.Any(y => y.DetailList.Any(z => z.ColorType.Equals("Red")))
                   //where
                 select x ? source.Value.Where(y => y.DetailList.Any(z => z.ColorType.Equals("Red"))).Max(x =>                    x.EventDate) : //some default value;

Basically if the check is true you'll get the EventDate property otherwise a default value chosen by you.

+1
David Smith4y ago
As the linq is querying through hundreds of records I get an error Sequence contain no elements how to get pass that error even if that's true. I don't won't that error happening in the middle of that run. Is there away to modify the linq to just return empty or 0 if case is zero
+1
Simone Cappelletti4y ago
Hello, try something like:

var query = from source in dataList.AsEnumerable()

                 let x = source.Value.Where(y => y.DetailList.Any(z => z.ColorType.Equals("Red"))).ToArray()

                 //where

                 select x.Max(y => y.EventDate);

I saved the list in a variable named x for convenience and that you can reuse in the clause where to add some logic.
+1
Mario Scheeren4y ago
var date = dataList.Where(x => x.DetailList.Any(y => y.ColorType == "Red")).Max(x => x.EventDate);
+1