Sorting by column name string

Question

I have an observable collection. I want to use linq to sort it. I have the propertyname of the property I want to sort (as a string) for my type.

What is the best/fastest way to do this?

Different propertyname strings will be passed into the function

Answer 1

I have only ever been able to do this through reflection.

var v = YouList.OrderBy(t => t.GetType().InvokeMember(sField,
    System.Reflection.BindingFlags.GetProperty,
    null,
    t,
    null)
).ToList());

I'm assuming the same code will work for an ObservableCollection...

Answer 2

You should be able to construct an Expression from that property name and pass that to OrderBy:

public IEnumerable<MyData> orderByDynamic(IEnumerable<MyData> objects, string propertyName) 
{
    var parameterExpression = Expression.Parameter(typeof(MyData), "x");
    var orderByExpression = Expression.Lambda<Func<MyData, TypeOfProperty>>(
        Expression.Property(parameterExpression, propertyName),
        parameterExpression);  
    return objects.OrderBy(orderByExpression)
}

The problem is that you need to know the type of the property at compile time for this to work.

Answer 3

You can do sorting by using lambdas. I copied what's in the internal class used by the DataGrid:

        IEnumerable<T> sortedList = _list.ToArray<T>();

        foreach (SortDescription sortDescription in SortDescriptions)
        {
            PropertyInfo propertyInfo = typeof(T).GetProperty(sortDescription.PropertyName);
            Func<T, object> keySelector = item => propertyInfo.GetValue(item, null);

            switch (sortDescription.Direction)
            {
                case ListSortDirection.Ascending:
                    sortedList = sortedList.OrderBy(keySelector);
                    break;
                case ListSortDirection.Descending:
                    sortedList = sortedList.OrderByDescending(keySelector);
                    break;
                default:
                    continue;
            }
        }

        T currentItem = _currentItem;

Works quite nicely and better than trying to find an IComparer.