CustomFunctions Class

Contains static methods to register a custom function for the End-User Report Designer‘s Expression Editor.

Namespace: DevExpress.XtraReports.Expressions

Assembly: DevExpress.XtraReports.v20.2.dll

NuGet Packages: DevExpress.Reporting.Core, DevExpress.WindowsDesktop.Reporting.Core

Declaration

C#

public static class CustomFunctions

VB.NET

Public Module CustomFunctions

Remarks

The CustomFunctions class allows you to register a custom function that users can utilize in the Expression Editor for expression bindings and calculated fields.

A custom function implements the DevExpress.XtraReports.Expressions.ReportCustomFunctionOperatorBase interface.

The following code defines a custom function:

CustomFormatFunction.cs

using DevExpress.XtraReports.Expressions;
using System;
// ...
    public class CustomFormatFunction : ReportCustomFunctionOperatorBase
    {
        public override string FunctionCategory 
            => "String";
        public override string Description 
            => "CustomFormatFunction(string format, object arg0)" +
            "\r\nConverts an arg0 value to a string based on a specified format";
        public override bool IsValidOperandCount(int count) 
            => count == 2;
        public override bool IsValidOperandType(int operandIndex, int operandCount, Type type) 
            => true;
        public override int MaxOperandCount
            => 2;
        public override int MinOperandCount
            => 2;
        public override object Evaluate(params object[] operands)
        {
            string res = String.Format(operands[0].ToString(), operands[1]);
            return res;
        }
        public override string Name 
            => "CustomFormatFunction";
        public override Type ResultType(params Type[] operands)
        {
            return typeof(string);
        }
    }

CustomFormatFunction.vb

Imports DevExpress.XtraReports.Expressions
Imports System
' ...
    Public Class CustomFormatFunction
        Inherits ReportCustomFunctionOperatorBase

        Public Overrides ReadOnly Property FunctionCategory() As String
            Get
                Return "String"
            End Get
        End Property
        Public Overrides ReadOnly Property Description() As String
            Get
                Return "CustomFormatFunction(string format, object arg0)"_
                & ControlChars.CrLf & "Converts an arg0 value to a string based on a specified format"
            End Get
        End Property
        Public Overrides Function IsValidOperandCount(ByVal count As Integer) As Boolean
            Return count = 2
        End Function
        Public Overrides Function IsValidOperandType(ByVal operandIndex As Integer,_
            ByVal operandCount As Integer, ByVal type As Type) As Boolean
            Return True
        End Function
        Public Overrides ReadOnly Property MaxOperandCount() As Integer
            Get
                Return 2
            End Get
        End Property
        Public Overrides ReadOnly Property MinOperandCount() As Integer
            Get
                Return 2
            End Get
        End Property
        Public Overrides Function Evaluate(ParamArray ByVal operands() As Object) As Object
            Dim res As String = String.Format(operands(0).ToString(), operands(1))
            Return res
        End Function
        Public Overrides ReadOnly Property Name() As String
            Get
                Return "CustomFormatFunction"
            End Get
        End Property
        Public Overrides Function ResultType(ParamArray ByVal operands() As Type) As Type
            Return GetType(String)
        End Function
    End Class

Call the static CustomFunctions.Register method to register a custom function. Pass the custom function class instance as a parameter. To unregister a custom function, use the static CustomFunctions.Unregister method.

The following code registers a custom function for use in the End-User Designer:

Form1.cs

private void Form1_Load(object sender, EventArgs e)
{
    DevExpress.XtraReports.Expressions.CustomFunctions.Register(new NewLineConstant());
    DevExpress.XtraReports.Expressions.CustomFunctions.Register(new CustomFormatFunction());
    reportDesigner1.OpenReport("Reports\\XtraReport1.repx");
}

Form1.vb

Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    DevExpress.XtraReports.Expressions.CustomFunctions.Register(New NewLineConstant())
    DevExpress.XtraReports.Expressions.CustomFunctions.Register(New CustomFormatFunction())
    reportDesigner1.OpenReport("Reports\XtraReport1.repx")
End Sub

Inheritance

Object

CustomFunctions