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Posted 1 Dec 2008


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Implementing a Sortable BindingList Very, Very Quickly

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1 Dec 2008CPOL2 min read
A custom implementation of BindingList that provides sorting for every property of type T.



Implementing parent-child hierarchies (for example, a Sale object and the SaleDetails associated with it) is one of the most common scenarios encountered when modeling the entities in a business domain. If you implement the business objects using classes, a collection of child objects will typically be stored in a List<T>. However, List<T>, will prove anemic should you require a rich user interface built on top of the .NET framework's support for data binding.

The typical solution will be to wrap the List<T> in a BindingSource in order to take advantage of its design time support for data binding. That road will only take you so far as a critical feature will be absent - support for sorting.

This article will seek to remedy that by providing a custom implementation of a BindingList<T> that will automatically provide the methods required to provide sorting capability on every property defined in type T.

Implementation Objectives

  • Support sorting on all properties by instantiating an instance of the custom implementation of the BindingList<T>. E.g., write:
  • C#
    MySortableBindingList<SaleDetails>sortableSaleDetails = 
                          new MySortableBindingList<SaleDetail>();

    and get the sorting functionality.

Motivating Example

To illustrate this approach, we shall model two classes, Sale and SaleDetail, as follows:

public class Sale {

    public Sale() {
        SaleDate = DateTime.Now;

    public MySortableBindingList<SaleDetail> SaleDetails { get; set; }
    public string Salesman { get; set; }
    public string Client { get; set; }
    public DateTime SaleDate { get; set; }

    public decimal TotalAmount {
        get {
            Debug.Assert(SaleDetails != null);
            return SaleDetails.Sum(a => a.TotalAmount);

public class SaleDetail {

    public string Product { get; set; }
    public int Quantity { get; set; }
    public decimal UnitPrice { get; set; }

    public decimal TotalAmount {
        get {
            return UnitPrice * Quantity;

The above classes are just simple enough to illustrate the main concepts behind the article, as validation, persistence, error handling etc., are beyond the scope of the article.

Subclassing BindingList<T>

First, the code:

public class MySortableBindingList<T> : BindingList<T> {

    // reference to the list provided at the time of instantiation
    List<T> originalList;
    ListSortDirection sortDirection;
    PropertyDescriptor sortProperty;

    // function that refereshes the contents
    // of the base classes collection of elements
    Action<MySortableBindingList<T>, List<T>> 
                   populateBaseList = (a, b) => a.ResetItems(b);

    // a cache of functions that perform the sorting
    // for a given type, property, and sort direction
    static Dictionary<string, Func<List<T>, IEnumerable<T>>> 
       cachedOrderByExpressions = new Dictionary<string, Func<List<T>, 

    public MySortableBindingList() {
        originalList = new List<T>();

    public MySortableBindingList(IEnumerable<T> enumerable) {
        originalList = enumerable.ToList();
        populateBaseList(this, originalList);

    public MySortableBindingList(List<T> list) {
        originalList = list;
        populateBaseList(this, originalList);

    protected override void ApplySortCore(PropertyDescriptor prop, 
                            ListSortDirection direction) {
         Look for an appropriate sort method in the cache if not found .
         Call CreateOrderByMethod to create one. 
         Apply it to the original list.
         Notify any bound controls that the sort has been applied.

        sortProperty = prop;

        var orderByMethodName = sortDirection == 
            ListSortDirection.Ascending ? "OrderBy" : "OrderByDescending";
        var cacheKey = typeof(T).GUID + prop.Name + orderByMethodName;

        if (!cachedOrderByExpressions.ContainsKey(cacheKey)) {
            CreateOrderByMethod(prop, orderByMethodName, cacheKey);

        sortDirection = sortDirection == ListSortDirection.Ascending ? 
                        ListSortDirection.Descending : ListSortDirection.Ascending;

    private void CreateOrderByMethod(PropertyDescriptor prop, 
                 string orderByMethodName, string cacheKey) {

         Create a generic method implementation for IEnumerable<T>.
         Cache it.

        var sourceParameter = Expression.Parameter(typeof(List<T>), "source");
        var lambdaParameter = Expression.Parameter(typeof(T), "lambdaParameter");
        var accesedMember = typeof(T).GetProperty(prop.Name);
        var propertySelectorLambda =
                              accesedMember), lambdaParameter);
        var orderByMethod = typeof(Enumerable).GetMethods()
                                      .Where(a => a.Name == orderByMethodName &&
                                                   a.GetParameters().Length == 2)
                                      .MakeGenericMethod(typeof(T), prop.PropertyType);

        var orderByExpression = Expression.Lambda<Func<List<T>, IEnumerable<T>>>(
                                            new Expression[] { sourceParameter, 
                                                               propertySelectorLambda }),

        cachedOrderByExpressions.Add(cacheKey, orderByExpression.Compile());

    protected override void RemoveSortCore() {

    private void ResetItems(List<T> items) {


        for (int i = 0; i < items.Count; i++) {
            base.InsertItem(i, items[i]);

    protected override bool SupportsSortingCore {
        get {
            // indeed we do
            return true;

    protected override ListSortDirection SortDirectionCore {
        get {
            return sortDirection;

    protected override PropertyDescriptor SortPropertyCore {
        get {
            return sortProperty;

    protected override void OnListChanged(ListChangedEventArgs e) {
        originalList = base.Items.ToList();

In a Nutshell

If, for instance, you create a MySortableBindingList<Sale> and sort on the Customer property, an expression that conceptually looks something like Enumerable.OrderBy<Sale>(originalList, a => a.Customer) will be created and used to do the sorting.

The code to create the sample data and set up the data binding:

public void OnLoad(object source, EventArgs e) {

    var sales = new[] {
        new Sale(){

            Client = "Jahmani Mwaura",
            SaleDate = new DateTime(2008,1,1),
            Salesman = "Gachie",

            SaleDetails = new MySortableBindingList<SaleDetail>(){

                new SaleDetail(){
                    Product = "Sportsman",
                    Quantity = 1,
                    UnitPrice = 80

                 new SaleDetail(){
                    Product = "Tusker Malt",
                    Quantity = 2,
                    UnitPrice = 100

                new SaleDetail(){
                    Product = "Alvaro",
                    Quantity = 1,
                    UnitPrice = 50

        new Sale(){

            Client = "Ben Kones",
            SaleDate = new DateTime(2008,1,1),
            Salesman = "Danny",

            SaleDetails = new MySortableBindingList<SaleDetail>(){

                new SaleDetail(){
                    Product = "Embassy Kings",
                    Quantity = 1,
                    UnitPrice = 80

                 new SaleDetail(){
                    Product = "Tusker",
                    Quantity = 5,
                    UnitPrice = 100

                new SaleDetail(){
                    Product = "Novida",
                    Quantity = 3,
                    UnitPrice = 50

        new Sale(){

            Client = "Tim Kim",
            SaleDate = new DateTime(2008,1,1),
            Salesman = "Kiplagat",

            SaleDetails = new MySortableBindingList<SaleDetail>(){

                new SaleDetail(){
                    Product = "Citizen Special",
                    Quantity = 10,
                    UnitPrice = 30


                new SaleDetail(){
                    Product = "Burn",
                    Quantity = 2,
                    UnitPrice = 100

    saleBindingSource.DataSource = new MySortableBindingList<Sale>(sales);

Seeing it at work

You can download the samples at the top of the page and see it at work for yourself. I hope you enjoy.



  • December 2, 2008: Article posted.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Written By
Technical Lead Olivine Technology
Kenya Kenya
Technical Lead, Olivine Technology - Nairobi, Kenya.

"The bane of productivity: confusing the rituals of work (sitting at your desk by 8:00am, wearing a clean and well pressed business costume etc.) with actual work that produces results."

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Comments and Discussions

GeneralMy vote of 1 Pin
atverweij4-Feb-21 8:05
Memberatverweij4-Feb-21 8:05 
PraiseCongratulations! Pin
marcelo iván rojas hernández14-Aug-18 3:58
Membermarcelo iván rojas hernández14-Aug-18 3:58 
PraisePERFECT! Pin
APE-Germany7-Mar-17 2:18
MemberAPE-Germany7-Mar-17 2:18 
QuestionThanks for writing article, really helpful! Pin
vladabuba21-Jul-15 0:38
Membervladabuba21-Jul-15 0:38 
QuestionHow can i sort DataGridView using this by two columns? Pin
revitarkitek17-Jun-15 5:02
Memberrevitarkitek17-Jun-15 5:02 
QuestionI have Second Level Properties, This is not working. Help is appreciated. Thanks! Pin
AshokDNet26-Feb-15 12:49
MemberAshokDNet26-Feb-15 12:49 
QuestionWow - since 7 years. Pin
snoopy0013-Feb-15 12:02
Membersnoopy0013-Feb-15 12:02 
QuestionPerfect - thanks! Pin
scott.leckie12-Nov-14 6:01
Memberscott.leckie12-Nov-14 6:01 
SuggestionMore lightweigt and speeded up for multicore CPU Pin
Physlcu$7-Apr-13 5:49
MemberPhyslcu$7-Apr-13 5:49 
GeneralRe: More lightweigt and speeded up for multicore CPU Pin
Muigai Mwaura19-Apr-13 14:50
MemberMuigai Mwaura19-Apr-13 14:50 
GeneralRe: More lightweigt and speeded up for multicore CPU Pin
Jackcolt29-Apr-13 1:59
MemberJackcolt29-Apr-13 1:59 
GeneralRe: More lightweigt and speeded up for multicore CPU Pin
dedlok9-Apr-14 5:24
Memberdedlok9-Apr-14 5:24 
SuggestionRe: More lightweigt and speeded up for multicore CPU Pin
AqpA3-Feb-15 10:49
MemberAqpA3-Feb-15 10:49 
GeneralRe: More lightweigt and speeded up for multicore CPU Pin
khokon7723-Aug-15 23:23
Memberkhokon7723-Aug-15 23:23 
GeneralRe: More lightweigt and speeded up for multicore CPU Pin
Member 411323415-Mar-16 22:42
MemberMember 411323415-Mar-16 22:42 
GeneralRe: More lightweigt and speeded up for multicore CPU Pin
sbussing20-Oct-17 23:32
Membersbussing20-Oct-17 23:32 
SuggestionDataGridView connected with Linq Pin
Dennnis19-Mar-13 7:39
MemberDennnis19-Mar-13 7:39 
GeneralRe: DataGridView connected with Linq Pin
Muigai Mwaura19-Mar-13 21:54
MemberMuigai Mwaura19-Mar-13 21:54 
SuggestionOnListChanged Function Pin
Mathew Crothers17-Oct-12 15:07
professionalMathew Crothers17-Oct-12 15:07 
GeneralRe: OnListChanged Function Pin
Muigai Mwaura9-Nov-12 6:17
MemberMuigai Mwaura9-Nov-12 6:17 
QuestionThanks. Pin
Brady Kelly25-Sep-12 2:54
MemberBrady Kelly25-Sep-12 2:54 
AnswerRe: Thanks. Pin
Muigai Mwaura9-Nov-12 6:13
MemberMuigai Mwaura9-Nov-12 6:13 
SuggestionSpeeding up loading and sorting... Pin
OICU81213-Apr-12 6:38
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GeneralRe: Speeding up loading and sorting... Pin
Muigai Mwaura19-Jun-12 8:49
MemberMuigai Mwaura19-Jun-12 8:49 
GeneralMuch more simple realization PinPopular
killmeplease15-Apr-11 23:10
Memberkillmeplease15-Apr-11 23:10 

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