Conditional “orderby” sort order in LINQ

Question

In LINQ, is it possible to have conditional orderby sort order (ascending vs. descending).

Something like this (not valid code):

bool flag;

(from w          


        

Answer 1

Here is a more general solution, that can be used for various conditional lambda expressions without breaking the flow of the expression.

public static IEnumerable IfThenElse(
    this IEnumerable elements,
    Func condition,
    Func, IEnumerable> thenPath,
    Func, IEnumerable> elsePath)
{
    return condition()
        ? thenPath(elements)
        : elsePath(elements);
}

e.g.

var result = widgets
    .Where(w => w.Name.Contains("xyz"))
    .IfThenElse(
        () => flag,
        e => e.OrderBy(w => w.Id),
        e => e.OrderByDescending(w => w.Id));