Question

I’m using grails 1.3.7.

I have the following filter setup:

class MyFilters {
    def userService
    def springSecurityService

    def filters = {
        all(controller: '*', action: '*') {
            before = {
                String userAgent = request.getHeader('User-Agent')

                int buildVersion = 0

                // Match "app-/{version}" where {version} is the build number
                def matcher = userAgent =~ "(?i)app(?:-\\w+)?\\/(\\d+)"

                if (matcher.getCount() > 0)
                {                   
                    buildVersion = Integer.parseInt(matcher[0][1])

                    log.info("User agent is from a mobile with build version = " + buildVersion)
                    log.info("User agent = " + userAgent)

                    String redirectUrl = "https://anotherdomain.com"

                    if (buildVersion > 12)
                    {
                        if (request.queryString != null)
                        {
                            log.info("Redirecting request to anotherdomain with query string")
                            redirect(url:"${redirectUrl}${request.forwardURI}?${request.queryString}",params:params)
                        }

                        return
                    }
                }
            }
            after = { model ->
                if (model) {
                    model['currentUser'] = userService.currentUser
                }
            }
            afterView = {

            }
        }
    }
}

A problem occurs in that the redirect does not happen at the point I would have thought.
I want all execution to stop and redirect to the exaact url I have given it at this point.

When i debug to the “redirect” line, it continues past this line exectuting other lines and jumping to another controller.

Answer 1

In order to prevent the normal processing flow from continuing, you need to return false from your before filter:

if (buildVersion > 12)
{
    if (request.queryString != null)
    {
        log.info("Redirecting request to anotherdomain with query string")
        redirect(url:"${redirectUrl}${request.forwardURI}?${request.queryString}",params:params)
        return false
    }
}

This is mentioned in passing at the very end of section 6.6.2 of the user guide, but it isn’t particularly prominent:

Note how returning false ensure that the action itself is not executed.