/// <summary>
/// Groups the elements of a sequence according to a specified key selector function.
/// </summary>
/// <param name="source"> An <see cref="IQueryable" /> whose elements to group.</param>
/// <param name="keySelector"> A function to extract the key for each element.</param>
/// <returns>
/// An <see cref="IQueryable"/> with <see cref="IGrouping{TKey,TElement}"/> items,
/// whose elements contains a sequence of objects and a key.
/// </returns>
public static IQueryable GroupBy(this IQueryable source, LambdaExpression keySelector)
{
return source.CallQueryableMethod("GroupBy", keySelector);
}
/// <summary>
/// Sorts the elements of a sequence in descending order according to a key.
/// </summary>
/// <returns>
/// An <see cref="IQueryable" /> whose elements are sorted in descending order according to a key.
/// </returns>
/// <param name="source">
/// A sequence of values to order.
/// </param>
/// <param name="keySelector">
/// A function to extract a key from an element.
/// </param>
public static IQueryable OrderByDescending(this IQueryable source, LambdaExpression keySelector)
{
return source.CallQueryableMethod("OrderByDescending", keySelector);
}
/// <summary>
/// Projects each element of a sequence into a new form.
/// </summary>
/// <returns>
/// An <see cref="IQueryable" /> whose elements are the result of invoking a
/// projection selector on each element of <paramref name="source" />.
/// </returns>
/// <param name="source"> A sequence of values to project. </param>
/// <param name="selector"> A projection function to apply to each element. </param>
public static IQueryable Select(this IQueryable source, LambdaExpression selector)
{
return source.CallQueryableMethod("Select", selector);
}