Question

I have an enum:

 public enum Fruits
    {
       Apple = 14,
       Lemon = 174,
       Grapes = 200,
       Peach = 1
    }

and a list by this enum:

IEnumerable<Fruits> Fruits = new List<Fruits>();

By default when I call getValues on the enum it sorts the entries by their id.
I show the list as a dropdown in the UI and want to sort the members of the list in specific order. In my sample I want Lemon to be the first item in the list.

I tried to order the items by the Lemon entry with something like this:

Fruits.OrderBy(f => f.Lemon);

but I am not allowed to do this f.Lemon in this context. Maybe I can foreach the list remove the Lemon item and then insert it as a first entry.

I am quite new to programming and I have found some similar questions but not with enum type.

Answer 1

You can use OrderByDescending + ThenBy:

fruits.OrderByDescending(f => f == Fruits.Lemon)
      .ThenBy(f => f);

Note that the variable should have a different name than the enum type (I’ve used lowercase fruits).

If you want to order second by the name:

      .ThenBy(f => f.ToString());

f == Fruits.Lemon returns a bool which you can order by. It’s similar to SQL CASE:

ORDER BY CASE WHEN Fruit = 'Lemon' THEN 1 ELSE 0 END DESC, FRUIT ASC