sourceafBedSheet::IeAjaxCacheBustingFilter.fan

using afIoc::Inject

** Prevents IE from caching Ajax and CORS requests. Sets the following response http headers:
** 
** pre>
**   Cache-Control: max-age=0,no-cache,no-store,post-check=0,pre-check=0"
**   Expires:       Mon, 26 Jul 1997 05:00:00 GMT"
** <pre
const class IeAjaxCacheBustingFilter {
    
    @Inject
    private const HttpRequest req

    @Inject
    private const HttpResponse res
    
    @Inject
    private const BrowserDetection browserDetection
    
    internal new make(|This|in) { in(this) }
    
    ** 
    ** 'uri' param not used.
    public Bool service(Uri uri := ``) {

        if (browserDetection.isInternetExplorer) {
            // IE CORS requests from XDomainRequest don't set 'X-Requested-With' HTTP header. 
            // Bloody typical!!
            if (req.isXmlHttpRequest || req.headers.containsKey("Origin")) {
                // prevent IE from caching ajax calls
                // see http://www.codecouch.com/2009/01/how-to-stop-internet-explorer-from-caching-ajax-requests/
                res.headers["Cache-Control"]    = "max-age=0,no-cache,no-store,post-check=0,pre-check=0"
                res.headers["Expires"]          = "Mon, 26 Jul 1997 05:00:00 GMT"
            }
        }
        
        return false
    }
}