How can I sort a List<T> when the user clicks on a table header?

Question

I'm writing an asp.net mvc app and I've get a list of service calls that I display in a table. When the user clicks the table header I want to tell my controller to sort the list by that column.

public ActionResult Index(int? page, string sortBy, string sortDirection)
    {
        int pageIndex = page == null ? 0 : (int)page - 1;

        IServiceCallService scService = new ServiceCallService();
        IPagedList<ServiceCall> serviceCalls = scService.GetOpenServiceCalls("").ToPagedList(pageIndex, 2);

        return View("List", serviceCalls);
    }

How do I incorporate the sortBy and sortDirection. I think I could do something like:

IPagedList<ServiceCall> serviceCalls = sc.Service.GetOpenServiceCalls("").OrderBy(sortBy).ToPagedList(pageIndex, 2);

But that doesn't work because I assume OrderBy wants a lambda like p => p.CreateDate but not sure how to do this.

I know ways I could do it but they are ugly and I'm sure C# has something simple here that I'm just missing.

Thanks.

Answer 1

When sorting a generic list, you can provide the way to compare for sorting with an overload of List<T>.Sort():

public void Sort(
    Comparison<T> comparison
)

Here is the example from MSDN. The Comparison<T> comparison is a delegate that provides the method for comparing objects when sorting.

I may be wrong, but I believe if your list includes only items of the same type and that type implements IComparable, the delegate may not be necessary.

Answer 2

Don't forget about the handy-dandy DataBinder:

var serviceCalls = sc.Service.GetOpenServiceCalls("").OrderBy(call => DataBinder.Eval(call, sortBy));
return serviceCalls.ToPagedList(pageIndex, 2);

DataBinder.Eval from Msdn docs

Uses reflection to parse and evaluate a data-binding expression again an object at run time.

Answer 3

You could also use leverage jQuery and use something like Table Sorter if you're just looking to sort the list. It'd also be real time and all ajax-y.