ICustomFunctionOperator Interface

Declares the base functionality for custom functions.

Namespace: DevExpress.Data.Filtering

Assembly: DevExpress.Data.v18.1.dll

Declaration

C#

public interface ICustomFunctionOperator

VB.NET

Public Interface ICustomFunctionOperator

Related API Members

The following members accept/return ICustomFunctionOperator objects:

• CriteriaOperator.GetCustomFunction(String)
• FunctionInfo.CustomFunctionOperator

Remarks

The ICustomFunctionOperator interface declares only the essential members allowing you to identify a custom function and evaluate its values on the client. To add advanced capabilities to your custom functions, additional interfaces need to be implemented as well.

To allow evaluating the custom function on the database server side, implement the ICustomFunctionOperatorFormattable interface.

To make the custom function available for end-users in Expression Editor, implement the ICustomFunctionOperatorBrowsable interface. Refer to How to: Implement a Custom Criteria Language Function Operator for details.

To allow using the custom functions in LINQ to XPO expressions, implement the ICustomFunctionOperatorQueryable interface. Refer to How to: Implement Custom Functions and Criteria in LINQ to XPO for details.

Related GitHub Examples

The following code snippets (auto-collected from DevExpress Examples) contain references to the ICustomFunctionOperator interface.

Note

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.

C#

how-to-make-the-auto-filter-rows-filter-accent-insensitive-e5021/CS/DxSample/Filtering/RemoveDiacriticsFunction.cs#L7

namespace DxSample.Filtering {
    public sealed class RemoveDiacriticsFunction : ICustomFunctionOperator {
        object ICustomFunctionOperator.Evaluate(params object[] operands) {

server-mode-how-to-implement-a-distinct-count-aggregation-function-t329175/CS/CustomFunction_DistinctCount/DistinctCountFunction.cs#L11

namespace XPG_ServerMode_EF {
    class DistinctCountFunction : ICustomFunctionOperator, ICustomFunctionOperatorFormattable, IQueryableConvertible {
        internal const string Name = "DistinctCount";

XPO_how-to-implement-the-icustomfunctionoperatorformattable-interface-e2491/CS/DatePartFunction.cs#L25

object ICustomFunctionOperator.Evaluate(params object[] operands) {
    return GetMonth((DateTime)operands[0]);

how-to-use-a-custom-function-in-conditional-formatting-t167315/CS/CustomFilterOperationExample/CustomFunction/CustomFunction.cs#L10

{
    public class CustomFunction : ICustomFunctionOperator
    {

VB.NET

how-to-use-a-custom-function-in-conditional-formatting-t167315/VB/CustomFilterOperationExample/CustomFunction/CustomFunction.vb#L11

Public Class CustomFunction
    Implements ICustomFunctionOperator
    Public Function Evaluate(ParamArray operands As Object()) As Object Implements ICustomFunctionOperator.Evaluate

how-to-make-the-auto-filter-rows-filter-accent-insensitive-e5021/VB/DxSample/Filtering/RemoveDiacriticsFunction.vb#L8

Public NotInheritable Class RemoveDiacriticsFunction
    Implements ICustomFunctionOperator

server-mode-how-to-implement-a-distinct-count-aggregation-function-t329175/VB/CustomFunction_DistinctCount/DistinctCountFunction.vb#L12

Friend Class DistinctCountFunction
    Implements ICustomFunctionOperator, ICustomFunctionOperatorFormattable, IQueryableConvertible

XPO_how-to-implement-the-icustomfunctionoperatorformattable-interface-e2491/VB/DatePartFunction.vb#L28

Private Function Evaluate(ParamArray ByVal operands() As Object) As Object Implements ICustomFunctionOperator.Evaluate
    Return GetMonth(CDate(operands(0)))

how-to-register-a-custom-filter-function-and-use-it-in-gridcontrol-e3514/VB/WindowsApplication3/IsDayOffFunction.vb#L59

Public Function Evaluate(ParamArray ByVal operands() As Object) As Object Implements DevExpress.Data.Filtering.ICustomFunctionOperator.Evaluate
    Dim dt As DateTime = Convert.ToDateTime(operands(0))