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ColumnView.QueryCustomFunctions Event

Allows you to add custom-function-based filters (for example, ‘discount is more than 15%’) to Excel-style pop-up filter menus and/or the filter editor.

Namespace: DevExpress.XtraGrid.Views.Base

Assembly: DevExpress.XtraGrid.v24.1.dll

NuGet Packages: DevExpress.Win.Grid, DevExpress.Win.Navigation


public event QueryCustomFunctionsEventHandler QueryCustomFunctions

Event Data

The QueryCustomFunctions event's data class is DevExpress.XtraGrid.Views.Grid.CustomFunctionEventArgs.


To create a custom filter function (for example, ‘discount is more than 15%’), and add this function to Excel-style pop-up filter menus and/or the filter editor, do the following:

  • implement a custom function
  • register the function
  • add the function to pop-up filter menus and the filter editor in a QueryCustomFunctions event handler


Custom functions’ visibility depends on the ShowCustomFunctions property.


The example below shows how to add the Black Friday Discount filter to a grid view.


using DevExpress.Data.Filtering;

gridView1.QueryCustomFunctions += OnQueryCustomFunctions;

void OnQueryCustomFunctions(object sender, CustomFunctionEventArgs e) {
    if(e.PropertyName == "Discount")

public class IsBlackFridayDiscountFunction : ICustomFunctionDisplayAttributes {
    public const string FunctionName = "IsBlackFridayDiscount";
    static readonly IsBlackFridayDiscountFunction Instance = new IsBlackFridayDiscountFunction();
    IsBlackFridayDiscountFunction() { }
    public static void Register() {
    public static bool Unregister() {
        return CriteriaOperator.UnregisterCustomFunction(Instance);
    #region ICustomFunctionOperatorBrowsable Members
    public FunctionCategory Category {
        get { return FunctionCategory.Math; }
    public string Description {
        get { return "The discount amount is 15% or more."; }
    public bool IsValidOperandCount(int count) {
        return count == 1;
    public bool IsValidOperandType(int operandIndex, int operandCount, Type type) {
        return DevExpress.Data.Summary.SummaryItemTypeHelper.IsNumericalType(type);
    public int MaxOperandCount {
        get { return 1; }
    public int MinOperandCount {
        get { return 1; }
    #region ICustomFunctionDisplayAttributes
    public string DisplayName {
        get { return "Is Black Friday Discount"; }
    public object Image {
        get { return "bo_price"; }
    #region ICustomFunctionOperator Members
    public object Evaluate(params object[] operands) {
        double discount = Convert.ToDouble(operands[0]);
        return discount >= 0.15;
    public string Name {
        get { return FunctionName; }
    public Type ResultType(params Type[] operands) {
        return typeof(bool);


Run the following demo and click Open Solution for the complete example: XtraGrid.

In the case of a Code First data source, you can annotate data fields with the CustomFunction attribute.

public double Discount { get; set; }


To add custom functions to filter menus, filter editors, and conditional formatting dialogs of all DevExpress controls in the application, use the static (Shared in VB) QueryCustomFunctions event.

The following code snippet (auto-collected from DevExpress Examples) contains a reference to the QueryCustomFunctions event.


The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

See Also