public static IOrderedQueryable <T> ThenByDescending <T>(this IOrderedQueryable <T> query, String path)
{
Type currentType = typeof(T);
String[] parts = path.Split(',');
foreach (String part in parts)
{
PropertyInfo propInfo = currentType.GetProperty(part);
Type propType = propInfo.PropertyType;
String propFetchFunctionName = "ThenByDescending";
Type delegateType = typeof(Func <,>).MakeGenericType(currentType, propType);
ParameterExpression exprParam = Expression.Parameter(currentType, "it");
MemberExpression exprProp = Expression.Property(exprParam, part);
LambdaExpression exprLambda = Expression.Lambda(delegateType, exprProp, new ParameterExpression[] { exprParam });
Type orderExtensionMethodsType = typeof(Queryable);
List <Type> fetchMethodTypes = new List <Type>();
fetchMethodTypes.AddRange(query.GetType().GetGenericArguments().Take(2));
fetchMethodTypes.Add(propType);
MethodInfo fetchMethodInfo = orderExtensionMethodsType.GetMethods(BindingFlags.Static | BindingFlags.Public | BindingFlags.InvokeMethod).Where(x => x.Name == propFetchFunctionName && x.GetParameters().Length == 2).Single();
fetchMethodInfo = fetchMethodInfo.MakeGenericMethod(fetchMethodTypes.ToArray());
Object[] args = new Object[] { query, exprLambda };
query = fetchMethodInfo.Invoke(null, args) as IOrderedQueryable <T>;
currentType = propType;
}
return(query);
}
