Question

I am joining two datatables and selecting using LINQ. I am getting an error in the ‘orderby’ line. “The name ‘contact’ does not exist in the current context”. If I order by columns from the ‘customer’ variable it works, but not using columns from the ‘contact’ variable.

Then I removed the orderby line and tried to order it using lambda expression like:

orders.OrderBy(o => (string) o["ContactName"]; 

and I got an error “Cannot apply indexing with [] to an expression of type ‘AnonymousType#1’. I don’t want to create a new class just for sorting.

Any ideas how to do this kind of sorting. I will be doing a sort using multiple columns from both tables.

CODE:

  var orders = (from customer in Customers.AsEnumerable()
                          join contact in Contacts.AsEnumerable()
                              on (int) customer["CustomerID"] equals (int) contact["CustomerID"] into outer
                                from contact in outer.DefaultIfEmpty()
                                orderby contact["ContactName"]   
                          select new
                                     {
                                         ContactID = (int) contact["ContactID"]),
                                         Name =  (string) contact["ContactName"]),
                                         City =  (string) contact["City"])
                                  });

Answer 1

There are some syntax problems(too many paranthesis, f.e. contact["ContactID"])), this should work:

var orders =  from customer in Customers.AsEnumerable()
              join contact in Contacts.AsEnumerable()
              on customer.Field<int>("CustomerID") equals contact.Field<int>("CustomerID") into outer
                  from contact in outer.DefaultIfEmpty()
                  orderby contact["ContactName"]   
                  select new
                  {
                        ContactID = contact.Field<int>("ContactID"),
                        Name =  contact.Field<String>("ContactName"),
                        City =  contact.Field<String>("City")
                  };

Sidenote: i would use the strong type Field extension method.