Why can't I cast an int to a string within this ternary operation

Question

I left some code out for brevity...

int id = Convert.ToInt32(Page.RouteData.Values[\"id\"]);
var q = db.Categories.SingleOrDefault(x => x.categoryID == id);

         


        

Answer 1

Because your are trying to make the ternary operator evaluate to either an int (0) or a string (id.ToString()). Replace the 0 with "0".

Answer 2

Because the two return values of the ternary are not of the same type -- one is int and the other is string. The compiler cannot deduce what the ternary expression's return type is.

Solution: Return the same type from both branches, or cast one of them to a base of the other. object will do fine.