C# linq and sorting - linq

Question

With linq I want to use order by with specific column but I need two switches because i don't know how to use desc or asc in one
public class CustomersRepository : RepositoryBase<Customers>
{
public List<Customers> GetAll(CustomersProperties property, SortEnum sortEnum, int page, int limit)
{
var query = _context.Set<Customers>();
switch (sortEnum)
{
case SortEnum.Ascending:
switch (property)
{
case CustomersProperties.Name:
query = query.OrderBy(x => x.Name);
break;
case CustomersProperties.Surname:
query = query.OrderBy(x => x.Lastname);
break;
default:
throw new ArgumentOutOfRangeException("property");
}
break;
case SortEnum.Descending:
break;
default:
throw new ArgumentOutOfRangeException("sortEnum");
}
return query.Skip(page * limit)
.Take(limit).ToList();
}
}
Is it possible to do without two switch cases?

Answer 1

Be aware that query.OrderBy(x => x.Name); does not do anything since the sorted collection is returned from OrderBy, and you're not capturing that return.
That said, there's not a way to "dynamically" choose the direction in Linq. However, a conditional switch would be a little cleaner. Another option would be to capture the sort expression in a variable:
Expreccion<Func<Customers, string>> propExp;
switch (property)
{
case CustomersProperties.Name:
propExp = ((Customers)x => x.Name)
break;
case CustomersProperties.Surname:
propExp = ((Customers)x => x.Lastname);
break;
default:
throw new ArgumentOutOfRangeException("property");
}
query = sortEnum == SortEnum.Ascending
? query.OrderBy(propExp);
: query.OrderByDescending(propExp);

Answer 2

You could make your own overload, something like this:
public static IOrderedQueryable<TSource> OrderBy<TSource, TKey>(
this IQueryable<TSource> source,
Expression<Func<TSource, TKey>> keySelector, SortEnum sort) {
switch (sort) {
case SortEnum.Ascending:
return source.OrderBy(keySelector);
case SortEnum.Descending:
return source.OrderByDescending(keySelector);
default:
throw new ArgumentOutOfRangeException("sort");
}
}
// later on..
query = query.OrderBy(x => x.LastName, sortEnum);

Answer 3

You can prepare sortProperty Expression first and then use it with either OrderBy or OrderByDescending:
public List<Customers> GetAll(CustomersProperties property, SortEnum sortEnum, int page, int limit)
{
var query = _context.Set<Customers>();
Expression<Func<Customers, string>> sortProperty;
switch (property)
{
case CustomersProperties.Name:
sortProperty = x => x.Name;
break;
case CustomersProperties.Surname:
sortProperty = x => x.Lastname;
break;
default:
throw new ArgumentOutOfRangeException("property");
}
switch (sortEnum)
{
case SortEnum.Ascending:
query = query.OrderBy(sortProperty);
break;
case SortEnum.Descending:
query = query.OrderByDescending(sortProperty);
break;
default:
throw new ArgumentOutOfRangeException("sortEnum");
}
return query.Skip(page * limit)
.Take(limit).ToList();
}