Click here to Skip to main content
13,707,665 members
Click here to Skip to main content
Add your own
alternative version


86 bookmarked
Posted 1 Dec 2008
Licenced CPOL

Implementing a Sortable BindingList Very, Very Quickly

, 1 Dec 2008
Rate this:
Please Sign up or sign in to vote.
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.

"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."

Watch me!

You may also be interested in...

Comments and Discussions

GeneralRe: Not perfect Pin
Muigai Mwaura27-Jan-11 6:38
memberMuigai Mwaura27-Jan-11 6:38 
Generalmy vote of 5 Pin
unami8224-Sep-10 5:09
memberunami8224-Sep-10 5:09 
GeneralRe: my vote of 5 Pin
Muigai Mwaura24-Sep-10 6:38
memberMuigai Mwaura24-Sep-10 6:38 
NewsCodeplex Pin
Muigai Mwaura8-Aug-10 20:32
memberMuigai Mwaura8-Aug-10 20:32 
QuestionIs this a bug? Pin
Jason Brown26-Jul-10 6:28
memberJason Brown26-Jul-10 6:28 
AnswerRe: Is this a bug? Pin
Muigai Mwaura27-Jul-10 1:23
memberMuigai Mwaura27-Jul-10 1:23 
GeneralRe: Is this a bug? Pin
Daniel Castenholz5-Aug-10 7:35
memberDaniel Castenholz5-Aug-10 7:35 
GeneralRe: Is this a bug? Pin
Muigai Mwaura5-Aug-10 22:12
memberMuigai Mwaura5-Aug-10 22:12 
This is some good feedback. I'll incorporate the bug fixes that have been posted and set up a project on CodePlex to host the code this weekend.
GeneralMy vote of 5 Pin
Jason Brown26-Jul-10 0:46
memberJason Brown26-Jul-10 0:46 
GeneralRe: My vote of 5 Pin
Muigai Mwaura27-Jul-10 1:21
memberMuigai Mwaura27-Jul-10 1:21 
GeneralMy vote of 5 Pin
Member 15999454-Jul-10 3:35
memberMember 15999454-Jul-10 3:35 
GeneralRe: My vote of 5 Pin
Muigai Mwaura20-Jul-10 0:02
memberMuigai Mwaura20-Jul-10 0:02 
GeneralPlease Fix yours amazing class Pin
minskowl25-Sep-09 3:47
memberminskowl25-Sep-09 3:47 
GeneralRe: Please Fix yours amazing class Pin
Muigai Mwaura30-Sep-09 20:37
memberMuigai Mwaura30-Sep-09 20:37 
AnswerFixes Pin
jjbongo16-Feb-10 0:55
memberjjbongo16-Feb-10 0:55 
GeneralRe: Fixes Pin
Muigai Mwaura16-Feb-10 3:25
memberMuigai Mwaura16-Feb-10 3:25 
GeneralOrdering glyph not displayed correctly Pin
Tzvi_r27-Jul-09 4:13
memberTzvi_r27-Jul-09 4:13 
GeneralRe: Ordering glyph not displayed correctly Pin
Muigai Mwaura30-Sep-09 20:38
memberMuigai Mwaura30-Sep-09 20:38 
GeneralRe: Ordering glyph not displayed correctly Pin
冯科炜22-Jul-18 23:09
member冯科炜22-Jul-18 23:09 
GeneralI like this! Pin
JohnStodden24-Jul-09 1:08
memberJohnStodden24-Jul-09 1:08 
GeneralRe: I like this! Pin
Muigai Mwaura24-Jul-09 21:58
memberMuigai Mwaura24-Jul-09 21:58 
GeneralSimply amazing Pin
tigerfist55523-Jul-09 10:46
membertigerfist55523-Jul-09 10:46 
GeneralRe: Simply amazing Pin
Muigai Mwaura23-Jul-09 20:29
memberMuigai Mwaura23-Jul-09 20:29 
GeneralSeems to break automatic list change notifications... Pin
Sly2aar27-Jan-09 0:15
memberSly2aar27-Jan-09 0:15 
GeneralRe: Seems to break automatic list change notifications... Pin
Sly2aar27-Jan-09 0:55
memberSly2aar27-Jan-09 0:55 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

Permalink | Advertise | Privacy | Cookies | Terms of Use | Mobile
Web06-2016 | 2.8.180920.1 | Last Updated 2 Dec 2008
Article Copyright 2008 by Muigai Mwaura
Everything else Copyright © CodeProject, 1999-2018
Layout: fixed | fluid