CODEWITHSUNDEEP
linq
CallumVass
CallumVass

Reputation: 11458

LINQ - OrderBy explictly

Is it possible to use LINQ OrderBy like so:

.OrderBy(x=>(x.SourceID == 3), (x.SourceID == 2), (x=>x.SourceID == 4), (x.SourceID == 1)).ToList();

So it'll order them by 3, 2, 4, 1 ?

Upvotes: 3

Views: 321

Answers (2)

mjbates7
mjbates7

Reputation: 674

Taking Joachim Isaksson's answer above, this could be wrapped in an extension method:

public static class ListExtensions
{
    public static List<Source> SortByCustomOrder(this List<Source> list, List<int> sortOrder)
    {
        return list.OrderBy(x => sortOrder.IndexOf(x.SourceId)).ToList();
    }
}

replacing Source with your Class and x.SourceId with your property

Usage:

// the sort order
var sortOrder = new List<int> { 3, 2, 4, 1, 6, 5 };
var results = sources.SortByCustomOrder(sortOrder);

Upvotes: 2

Joachim Isaksson
Joachim Isaksson

Reputation: 181077

No, that is not a valid lambda expression. What you could do instead is something like;

var sortOrder = new List<int> {3, 2, 4, 1};
var result = bop.OrderBy(x=> sortOrder.IndexOf(x.SourceID)).ToList();

If you want to extend this to doing special things with unknowns (they end up first now), you can just make a method that makes the determination of the sort order and use that instead.

Upvotes: 7

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