LINQ - OrderBy explictly

Question

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 ?

Answer 1

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.