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Posted 28 Aug 2011

Handle GridView.OnSorting() and create sorting expression dynamically using LINQ

, 18 Jul 2014 CPOL
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How to create a sorting expression from GridViewSortEventArgs using LINQ Expression Tree.


The GridView control from ASP.NET 2.0 such as this one is great and widely used:

<asp:GridView runat="server" ID="gridPersons" 

         AutoGenerateColumns="false" AllowSorting="true" 

        <asp:BoundField HeaderText="First name" 

           DataField="FirstName" SortExpression="FirstName" />
        <asp:BoundField HeaderText="Last name" 

           DataField="LastName" SortExpression="LastName" />
protected void gridPersons_Sorting(object sender, GridViewSortEventArgs e)
    string sortExpression = e.SortExpression;

But has one significant limitation: sorting event argument GridViewSortEventArg is based on string values from markup. So it can't be directly used in programmatic sorting using LINQ,

This article describes how to convert a string argument into the sorting expression.


Let's assume we have a sequence of strongly typed class, say Person, and we want to bind it to a GridView and then sort it by clicking on the appropriate column:

class Person
    public string FirstName { get; set; }
    public string LastName { get; set; }

IEnumerable<Person> persons = GetPersons();
gridPersons.DataSource =  persons.ToArray();

Generally speaking, we could hard-code both the sorting expression (i.e., property to sort by) and the direction (ascending, descending):

protected void gridPersons_Sorting(object sender, GridViewSortEventArgs e)
    Func<Person, object> prop = null;
    switch (e.SortExpression)
        case "FirstName":
            prop = p => p.FirstName;
        case "LastName":
            prop = p => p.LastName;

    Func<IEnumerable<Person>, Func<Person, object>, IEnumerable<Person>> func = null;

    switch (e.SortDirection)
        case SortDirection.Ascending:
            func = (c, p) => c.OrderBy(p);
        case SortDirection.Descending:
            func = (c, p) => c.OrderByDescending(p);

    IEnumerable<Person> persons = GetPersons();
    persons = func(persons, prop);

    gridPersons.DataSource = persons.ToArray();

But such approach contains a number of disadvantages: all the object's properties are hard-coded, as well as the sorting directions. Much better would be to create all these dynamically.


Let's encapsulate the logic into a number of dedicated classes.

The first one converts SortDirection to Func<IEnumerable<T>, Func<T, object>, IEnumerable<T>> which is a function accepting a sequence and another function accepting object and returning one of its properties; and returning that sequence sorted by that object's property.

public static class SortExpressionConverter<T>
    private static IDictionary<SortDirection, ISortExpression> expressions = 
        new Dictionary<SortDirection, ISortExpression>
        { SortDirection.Ascending, new OrderByAscendingSortExpression() },
        { SortDirection.Descending, new OrderByDescendingSortExpression() }

    interface ISortExpression
        Func<IEnumerable<T>, Func<T, object>, IEnumerable<T>> GetExpression();

    class OrderByAscendingSortExpression : ISortExpression
        public Func<IEnumerable<T>, Func<T, object>, IEnumerable<T>> GetExpression()
            return (c, f) => c.OrderBy(f);

    class OrderByDescendingSortExpression : ISortExpression
        public Func<IEnumerable<T>, Func<T, object>, IEnumerable<T>> GetExpression()
            return (c, f) => c.OrderByDescending(f);

    public static Func<IEnumerable<T>, Func<T, object>, IEnumerable<T>>
        Convert(SortDirection direction)
        ISortExpression sortExpression = expressions[direction];
        return sortExpression.GetExpression();

The second one builds a lambda expression Expression<Func<T, object>> and returns underlying lambda Func<T, object>:

public static class SortLambdaBuilder<T>
    public static Func<T, object> Build(string columnName, SortDirection direction)
        // x
        ParameterExpression param = Expression.Parameter(typeof(T), "x");

        // x.ColumnName1.ColumnName2
        Expression property = columnName.Split('.')
                                        .Aggregate<string, Expression>
                                        (param, (c, m) => Expression.Property(c, m));

        // x => x.ColumnName1.ColumnName2
        Expression<Func<T, object>> lambda = Expression.Lambda<Func<T, object>>(
            Expression.Convert(property, typeof(object)),
        Func<T, object> func = lambda.Compile();
        return func;

Wrap how these classes are used into an extension method:

public static class CollectionExtensions
    public static IEnumerable<T> OrderBy<T>(this IEnumerable<T> collection, 
           string columnName, SortDirection direction)
        Func<IEnumerable<T>, Func<T, object>, IEnumerable<T>> expression =

        Func<T, object> lambda =
            SortLambdaBuilder<T>.Build(columnName, direction);

        IEnumerable<T> sorted = expression(collection, lambda);
        return sorted;

So now we have a flexible, fully dynamic and generic solution:

protected void gridPersons_Sorting(object sender, GridViewSortEventArgs e)
    IEnumerable<Person> persons = GetPersons();
    persons = persons.OrderBy(e.SortExpression, e.SortDirection);

    gridPersons.DataSource = persons.ToArray();

Points of Interest 

Here are some discussions on StackOverflow related to the subject:

History of Changes

  • 27/08/2011 - Initial publication
  • 22/03/2012 - OrderBy<T>() extension method expanded to make it easier to read and understand
  • 17/07/2014 - SortLambdaBuilder<T> supports nested properties


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


About the Author

Alexander Batishchev
Software Developer
United States United States
.NET developer and architect

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Comments and Discussions

QuestionAscending and Descending on IEnumerable in LINQ Pin
matrix38827-Apr-15 8:43
membermatrix38827-Apr-15 8:43 
QuestionNot supporting custom properties -- complex objects Pin
Member 1079109110-Jun-14 6:53
memberMember 1079109110-Jun-14 6:53 
AnswerRe: Not supporting custom properties -- complex objects Pin
Alexander Batishchev12-Jun-14 12:10
memberAlexander Batishchev12-Jun-14 12:10 
GeneralRe: Not supporting custom properties -- complex objects Pin
Member 1079109116-Jul-14 8:08
memberMember 1079109116-Jul-14 8:08 
GeneralRe: Not supporting custom properties -- complex objects Pin
Alexander Batishchev17-Jul-14 8:25
memberAlexander Batishchev17-Jul-14 8:25 
GeneralRe: Not supporting custom properties -- complex objects Pin
Member 1079109117-Jul-14 8:33
memberMember 1079109117-Jul-14 8:33 
AnswerRe: Not supporting custom properties -- complex objects Pin
Alexander Batishchev17-Jul-14 11:31
memberAlexander Batishchev17-Jul-14 11:31 
GeneralRe: Not supporting custom properties -- complex objects Pin
Alexander Batishchev21-Jul-14 10:07
memberAlexander Batishchev21-Jul-14 10:07 
GeneralRe: Not supporting custom properties -- complex objects Pin
Member 1079109121-Jul-14 11:05
memberMember 1079109121-Jul-14 11:05 
GeneralMy vote of 5 Pin
Juhi Paunikar18-Apr-13 3:13
memberJuhi Paunikar18-Apr-13 3:13 
GeneralRe: My vote of 5 Pin
Alexander M. Batishchev18-Apr-13 19:07
memberAlexander M. Batishchev18-Apr-13 19:07 
SuggestionEnabling sub-property sorting Pin
iJazz Pizz31-Jan-13 5:37
memberiJazz Pizz31-Jan-13 5:37 
GeneralRe: Enabling sub-property sorting Pin
Alexander M. Batishchev18-Apr-13 19:17
memberAlexander M. Batishchev18-Apr-13 19:17 
GeneralRe: Enabling sub-property sorting Pin
sashidhar18-Sep-13 21:43
membersashidhar18-Sep-13 21:43 
QuestionDynamic.cs Pin
tmbgfan22-Mar-12 6:32
membertmbgfan22-Mar-12 6:32 
AnswerRe: Dynamic.cs Pin
Alexander M. Batishchev22-Mar-12 7:11
memberAlexander M. Batishchev22-Mar-12 7:11 
GeneralRe: Dynamic.cs Pin
tmbgfan22-Mar-12 8:16
membertmbgfan22-Mar-12 8:16 
QuestionExplaination Pin
KnvnBhat21-Mar-12 19:52
memberKnvnBhat21-Mar-12 19:52 
AnswerRe: Explaination Pin
Alexander M. Batishchev21-Mar-12 21:53
memberAlexander M. Batishchev21-Mar-12 21:53 
QuestionIt does not work properly... Pin
julgon200220-Mar-12 8:23
memberjulgon200220-Mar-12 8:23 
QuestionRe: It does not work properly... Pin
Alexander M. Batishchev21-Mar-12 5:22
memberAlexander M. Batishchev21-Mar-12 5:22 
SuggestionNeeded changes Pin
Leoric229-Aug-11 2:27
memberLeoric229-Aug-11 2:27 
GeneralRe: Needed changes Pin
Alexander M. Batishchev21-Mar-12 21:55
memberAlexander M. Batishchev21-Mar-12 21:55 
QuestionGood code but no explanation :( Pin
David Zenou28-Aug-11 8:02
memberDavid Zenou28-Aug-11 8:02 
AnswerRe: Good code but no explanation :( Pin
Alexander M. Batishchev28-Aug-11 8:11
memberAlexander M. Batishchev28-Aug-11 8:11 

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