Using Extension Methods

What is this page about?

This page explains how to use extension methods within LINQ Reporting Engine templates.

LINQ Reporting Engine enables you to use the following built‑in extension methods in template expressions:

• Extension methods mimicking the ones for IEnumerable<T> (see “Appendix A. Enumeration Extension Methods” for more information)
• Extension methods for iteration variables (see “Using Extension Methods of Iteration Variables” for more information)

Note – Extension methods, other than the built‑in ones, can be used only in the form of plain static methods in template expressions.

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FAQ

1. Q: How can I call a custom static method as an extension method in a LINQ Reporting Engine template?
   A: Place the method in a public static class, make the method itself public static, and reference it directly in the template expression using the full class name, e.g., MyUtilities.FormatDate(DateTime.Now). No additional registration is required.

2. Q: Are the built‑in extension methods available for iteration variables such as $row$?
   A: Yes. Iteration variables expose the same enumeration extension methods as IEnumerable<T>, so you can write expressions like $row$.Where(r => r.Price > 100) directly in the template.

3. Q: Can I use full LINQ query operators like Select or OrderBy inside a template expression?
   A: Only the extension methods listed in the documentation are supported. Full LINQ syntax is not available in template expressions; use the provided enumeration extension methods instead.

4. Q: Why do I receive a “Method not found” error when using an extension method in a template?
   A: The method must be public, static, and located in an assembly that the reporting engine can load. Also ensure the method signature uses only supported parameter types (primitive types, string, DateTime, etc.). Overloads with unsupported types will cause the engine to fail to locate the method.

5. Q: Can I return a custom object type from an extension method used in a template?
   A: The engine can render only primitive types, string, and DateTime directly. If your method returns a custom type, convert it to a supported type (e.g., ToString()) before using it in the template.