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Implementing a Sortable BindingList Very, Very Quickly

, 1 Dec 2008 CPOL
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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:
  • 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)


About the Author

Muigai Mwaura
Technical Lead Olivine Technology
Kenya Kenya
Technical Lead, Olivine Technology - Nairobi, Kenya.

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Comments and Discussions

QuestionI have Second Level Properties, This is not working. Help is appreciated. Thanks! PinmemberAshokDNet26-Feb-15 13:49 
QuestionWow - since 7 years. Pinmembersnoopy0013-Feb-15 13:02 
QuestionPerfect - thanks! Pinmemberscott.leckie12-Nov-14 7:01 
SuggestionMore lightweigt and speeded up for multicore CPU [modified] PinmemberLim6us7-Apr-13 6:49 
GeneralRe: More lightweigt and speeded up for multicore CPU PinmemberMuigai Mwaura19-Apr-13 15:50 
GeneralRe: More lightweigt and speeded up for multicore CPU PinmemberMember 805602829-Apr-13 2:59 
GeneralRe: More lightweigt and speeded up for multicore CPU Pinmemberdedlok9-Apr-14 6:24 
SuggestionRe: More lightweigt and speeded up for multicore CPU [modified] Pinmemberyesilbasmurat3-Feb-15 11:49 
SuggestionDataGridView connected with Linq PinmemberDennnis19-Mar-13 8:39 
GeneralRe: DataGridView connected with Linq PinmemberMuigai Mwaura19-Mar-13 22:54 
SuggestionOnListChanged Function PinmemberMathew Crothers17-Oct-12 16:07 
GeneralRe: OnListChanged Function PinmemberJahmani9-Nov-12 7:17 
QuestionThanks. PinmemberBrady Kelly25-Sep-12 3:54 
AnswerRe: Thanks. PinmemberJahmani9-Nov-12 7:13 
SuggestionSpeeding up loading and sorting... PinmemberOICU81213-Apr-12 7:38 
GeneralRe: Speeding up loading and sorting... PinmemberJahmani19-Jun-12 9:49 
GeneralMuch more simple realization Pinmemberkillmeplease16-Apr-11 0:10 
GeneralRe: Much more simple realization Pinmemberdreamgarden29-Sep-13 9:52 
NewsHere is another more general way [modified] Pinmemberkkyriako@yahoo.com30-Jan-11 9:36 
GeneralRe: Here is another more general way PinmemberJahmani3-Feb-11 22:22 
QuestionRe: Here is another more general way PinmemberMichael Ehrt20-Feb-11 21:11 
GeneralRe: Here is another more general way PinmemberGianni Gardini21-Feb-11 1:30 
GeneralRe: Here is another more general way [modified] PinmemberBigPilot9628-Nov-11 23:57 
GeneralRe: Here is another more general way PinmemberSonam K27-Dec-12 23:58 
GeneralMy vote of 5 Pinmember_clem25-Jan-11 7:36 
GeneralRe: My vote of 5 PinmemberJahmani27-Jan-11 7:37 
GeneralNot perfect PinmemberMember 740954117-Nov-10 1:51 
GeneralRe: Not perfect PinmemberJahmani27-Jan-11 7:38 
Generalmy vote of 5 Pinmemberunami8224-Sep-10 6:09 
GeneralRe: my vote of 5 PinmemberJahmani24-Sep-10 7:38 
NewsCodeplex PinmemberJahmani8-Aug-10 21:32 
QuestionIs this a bug? PinmemberJason Brown26-Jul-10 7:28 
AnswerRe: Is this a bug? PinmemberJahmani27-Jul-10 2:23 
GeneralRe: Is this a bug? PinmemberDaniel Castenholz5-Aug-10 8:35 
GeneralRe: Is this a bug? PinmemberJahmani5-Aug-10 23:12 
GeneralMy vote of 5 PinmemberJason Brown26-Jul-10 1:46 
GeneralRe: My vote of 5 PinmemberJahmani27-Jul-10 2:21 
GeneralMy vote of 5 PinmemberMember 15999454-Jul-10 4:35 
GeneralRe: My vote of 5 PinmemberJahmani20-Jul-10 1:02 
GeneralPlease Fix yours amazing class Pinmemberminskowl25-Sep-09 4:47 
GeneralRe: Please Fix yours amazing class PinmemberJahmani30-Sep-09 21:37 
AnswerFixes Pinmemberjjbongo16-Feb-10 1:55 
GeneralRe: Fixes PinmemberJahmani16-Feb-10 4:25 
GeneralOrdering glyph not displayed correctly PinmemberTzvi_r27-Jul-09 5:13 
GeneralRe: Ordering glyph not displayed correctly PinmemberJahmani30-Sep-09 21:38 
GeneralI like this! PinmemberJohnStodden24-Jul-09 2:08 
GeneralRe: I like this! PinmemberJahmani24-Jul-09 22:58 
GeneralSimply amazing Pinmembertigerfist55523-Jul-09 11:46 
GeneralRe: Simply amazing PinmemberJahmani23-Jul-09 21:29 
GeneralSeems to break automatic list change notifications... PinmemberSly2aar27-Jan-09 1:15 

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