Question

I’m trying to store expressions required by Linq OrderBy clauses in data structures, so I can just go query = query.OrderBy(MySortExpression);

OrderBy takes System.Linq.Expressions.Expression<Func<TSource,TKey>> as a parameter. TSource is the entity type you are sorting on, but what type is TKey supposed to be?

Answer 1

TKey is a generic type argument denoting the type of the expression on which you sort. For example, if you sort strings by length, TSource will be string, and TKey will be int, as in the code below:

string [] myStrings = new[] {"quick", "brown", "fox", "jumps"};
var ordered = myStrings.OrderBy(s => s.Length);