Using Extension Methods

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)

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FAQ

1. Q: How do I call an extension method inside a LINQ Reporting Engine template?
   A: Call it on a sequence inside an expression in square brackets, using the Java (camelCase) name, e.g., <<[persons.where(p => p.getAge() > 30).count()]>>, or in a data band: <<foreach [p in persons.where(p => p.getAge() > 30)]>>. The engine resolves the method at runtime.

2. Q: Which enumeration‑style extension methods are available by default?
   A: The methods that mimic the IEnumerable<T> extension methods, written in camelCase in Java templates: where, select, orderBy, take, skip, count, any, and the others listed in “Appendix A. Enumeration Extension Methods”.

3. Q: Can I use extension methods on the iteration variable itself (e.g., the index of a foreach loop)?
   A: Yes. Iteration variables have the indexOf() and numberOf() methods (see “Using Extension Methods of Iteration Variables”), e.g., <<[item.indexOf()]>>. There are no IsFirst, IsLast, or IsEven helpers; use expressions such as <<[item.indexOf() == 0 ? "First" : ""]>> instead.

4. Q: Is it possible to add my own custom extension methods for use in Java templates?
   A: Not as extension methods: only the built‑in extension methods can be called on a sequence. To use your own code, make the class and the method public and static, add the class to engine.getKnownTypes(), and call the method with the class name, e.g., <<[MyUtilities.formatDate(order.getOrderDate())]>>.

5. Q: Are the same extension methods available when using Aspose.Words for .NET or other platforms?
   A: Yes. .NET and Java have the same set of built‑in extension methods and the same << >> tag syntax. Only the method names follow the platform’s naming: Where, Count in .NET templates and where, count in Java templates. Refer to the platform‑specific documentation for details.