Generic Sorting using C# and Lambda Expression
- by Haitham Khedre
Download : GenericSortTester.zip I worked in this class from long time and I think it is a nice piece of code that I need to share , it might help other people searching for the same concept. this will help you to sort any collection easily without needing to write special code for each data type , however if you need special ordering you still can do it , leave a comment and I will see if I need to write another article to cover the other cases. I attached also a fully working example to make you able to see how do you will use that . public static class GenericSorter
{
public static IOrderedEnumerable<T> Sort<T>(IEnumerable<T> toSort,
Dictionary<string, SortingOrder> sortOptions)
{
IOrderedEnumerable<T> orderedList = null;
foreach (KeyValuePair<string, SortingOrder> entry in sortOptions)
{
if (orderedList != null)
{
if (entry.Value == SortingOrder.Ascending)
{
orderedList =
orderedList.ApplyOrder<T>(entry.Key, "ThenBy");
}
else
{
orderedList =
orderedList.ApplyOrder<T>(entry.Key,"ThenByDescending");
}
}
else
{
if (entry.Value == SortingOrder.Ascending)
{
orderedList =
toSort.ApplyOrder<T>(entry.Key, "OrderBy");
}
else
{
orderedList =
toSort.ApplyOrder<T>(entry.Key, "OrderByDescending");
}
}
}
return orderedList;
}
private static IOrderedEnumerable<T> ApplyOrder<T>
(this IEnumerable<T> source, string property, string methodName)
{
ParameterExpression param = Expression.Parameter(typeof(T), "x");
Expression expr = param;
foreach (string prop in property.Split('.'))
{
expr = Expression.PropertyOrField(expr, prop);
}
Type delegateType =
typeof(Func<,>).MakeGenericType(typeof(T), expr.Type);
LambdaExpression lambda =
Expression.Lambda(delegateType, expr, param);
MethodInfo mi = typeof(Enumerable).GetMethods().Single(
method => method.Name == methodName
&& method.IsGenericMethodDefinition
&& method.GetGenericArguments().Length == 2
&& method.GetParameters().Length == 2)
.MakeGenericMethod(typeof(T), expr.Type);
return (IOrderedEnumerable<T>)mi.Invoke
(null, new object[] { source, lambda.Compile() });
}
}
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