Question

I want to modify the response content of specific Grails requests. How do I configure a ResponseWrapper in a request filter?

I had hoped it would be the following, but the response is a read-only property:

class MyFilters {
    def filters = {
        wrapFoo(controller:'foo', action:'bar') {
            before = {
                response = new MyResponseWrapper(response)
            }
        [...]

Thanks!

Answer 1

You can’t – Grails filters are wrappers for Spring HandlerInterceptors and are invoked further up the processing chain than servlet filters. If you want to wrap the response you need to use a real servlet filter.

Create the class in src/java or src/groovy that implements javax.servlet.Filter and register it in web.xml like you would in a non-Grails application. To get access to web.xml run grails install-templates and edit the file in src/templates/war