private static IOrderedQueryable <TElement> InternalSort <TElement, TKey>(IOrderedQueryable <TElement> source, Expression <Func <TElement, TKey> > keySelector, SortingDirectionEnum direction)
{
var methodName = "ThenBy" + (direction == SortingDirectionEnum.Descending ? "Descending" : String.Empty);
var unary = (UnaryExpression)keySelector.Body;
if (unary.NodeType != ExpressionType.Convert)
{
throw new ArgumentException("Wrong node type", nameof(keySelector));
}
var member = (MemberExpression)unary.Operand;
var memberType = member.Member.GetMemberType();
var lambda = Expression.Lambda(member, keySelector.Parameters);
var sort = Expression.Call(typeof(Queryable), methodName,
new[] { source.ElementType, memberType },
source.Expression, lambda);
return((IOrderedQueryable <TElement>)source.Provider.CreateQuery <TElement>(sort));
}
public static IOrderedQueryable <TElement> ThenBy <TElement, TKey>(this IOrderedQueryable <TElement> source, Expression <Func <TElement, TKey> > keySelector, SortingDirectionEnum direction)
{
if (Reflector.Instance <TKey> .Type == Reflector.Instance <object> .Type)
{
return(InternalSort(source, keySelector, direction));
}
switch (direction)
{
case SortingDirectionEnum.Ascending:
return(source.ThenBy(keySelector));
case SortingDirectionEnum.Descending:
return(source.ThenBy(keySelector));
default:
throw new ArgumentOutOfRangeException(nameof(direction));
}
}
public static IOrderedQueryable <TElement> ThenBy <TElement>(this IOrderedQueryable <TElement> source, string propertyName, SortingDirectionEnum direction)
{
var keySelector = ExpressionExtensions.Create <TElement>(propertyName);
return(ThenBy(source, keySelector, direction));
}
public static IOrderedQueryable <TElement> OrderBy <TElement, TKey>(this IQueryable <TElement> source, Expression <Func <TElement, TKey> > keySelector, SortingDirectionEnum direction)
{
switch (direction)
{
case SortingDirectionEnum.Ascending:
return(source.OrderBy(keySelector));
case SortingDirectionEnum.Descending:
return(source.OrderByDescending(keySelector));
default:
throw new ArgumentOutOfRangeException(nameof(direction));
}
}
