Invalid anonymous type member declarator

Question

I have a problem with the following code which should work, according to this MSDN Forums post.

using System; using System.Collections.Generic; using System.IO; using System.Linq; using System.Text;  namespace LINQTest {     class Program     {         class Schedule         {             public int empid { get; set; }             public int hours { get; set; }             public DateTime date { get; set; }             public DateTime weekending { get; set; }         }          static void Main(string[] args)         {             List<Schedule> Schedules = new List<Schedule>();              var bla = from s in Schedules                       group s by new { s.empid, s.weekending} into g                       select new { g.Key.empid, g.Key.weekending, g.Sum(s=>s.hours)};         }     } } 

I'm getting the error with the sum function: Invalid anonymous type member declarator. Anonymous type members must be declared with a member assignment, simple name or member access.

What's wrong?

Answer 1

You have to name the property used to store Sum method result:

select new { g.Key.empid, g.Key.weekending, Sum = g.Sum(s=>s.hours)}; 

Compiler can't infer the property name when you're assigning the value from expression:

Anonymous Types (C# Programming Guide)

You must provide a name for a property that is being initialized with an expression (...)