Reporting for WinForms - How to Implement Custom Functions in the Expression Editor

This example adds custom functions to the list of functions available in the Expression Editor invoked in the WinForms End-User Report Designer.

This example implements the following functions:

1. The NewLineConstant function allows you to insert a new line into a string.

   This function uses the Environment.NewLine constant that returns a new line string defined for the current environment. You should enable the XRLabel.Multiline property to enable line breaks in the XRLabel text.

2. The CustomFormatFunction(string format, object arg0) function accepts a format string and a value to format.

   The function's Evaluate method uses the String.Format method to format a static string, data field, or a calculated field value.

Do the following to add a custom function to the End-User Report Designer's Expression Editor:

1. Implement the ICustomFunctionOperatorBrowsable interface to define your new custom function.
2. Call the CustomFunctions.Register method to register the implemented interface in the Report Designer.

Files to Review

• CustomFormatFunction.cs (VB: CustomFormatFunction.vb)
• NewLineFunction.cs (VB: NewLineFunction.vb)
• Form1.cs (VB: Form1.vb)

Documentation

• Custom Functions in the Expression Editor (WinForms)
• How to use a custom function in a query expression
• Custom Functions
• How to: Implement a Custom Criteria Language Function Operator

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