technically LOAD uses a GET, so returning the correct cache headers with a correct status **should** (read, every browser has its own implementation) avoid "fragment" (i.e. web2py component) refreshes. But if you return the same Etag with a 200 response with a content, the browser WILL replace it (you did anyhow request a refresh with an ajax call AND you're returning a content, it will be shameful to discard it). If you return a 304 with no content than the fragment shouldn't be replaced. This, however, is the theory. In practice, javascript has NO ACCESS to the etag (or cache) informations the browser has, so ajax doesn't work EXACTLY as normal browser GETs. You may even get around it, but then you'll be facing various browser implementations of it....
BTW, there is plenty of docs around the interwebs, such as http://juristr.com/blog/2013/06/caching-jquery-ajax-and-other-ie-fun/ What do you need this for ? isn't zillion times easier just to cache the response and send it ? On Thursday, August 7, 2014 7:19:40 PM UTC+2, mweissen wrote: > > Thank you for this information. Shall I use a jquery.ajax-call or can I > use the LOAD-helper? > > > 2014-08-07 11:24 GMT+02:00 Niphlod <[email protected] <javascript:>>: > >> if you trigger an ajax request, if it's a GET (an idempotent method) you >> may avoid reloading the page and get back a 304....................but it's >> not handled automatically by web2py unless the content is static. >> >> >> On Thursday, August 7, 2014 7:52:30 AM UTC+2, mweissen wrote: >>> >>> Dave told me that my explanation was not clear. Let me try it in other >>> words. What I want is a program which periodically reloads a page (I think >>> using LOAD is the best way), but only if I allow it. >>> >>> My idea was that the header parts "Last-Modified" and/or "ETag" could do >>> the job. Therefore I wrote the program in two steps: >>> >>> (1) A controller without any response header modification. It shows the >>> actual time and reloads once a second - everything is fine. >>> >>> The functions: >>> >>> def mytime(): >>> jetzt=str(request.now)[:19] >>> return dict(jetzt=jetzt) >>> >>> def init(): >>> return dict() >>> >>> ------------------------- >>> >>> The views: >>> >>> mytime.load: >>> {{=jetzt}} >>> >>> init.html: >>> {{extend 'layout.html'}} >>> {{=LOAD(f="mytime.load", ajax=True, timeout=1000, times="infinity")}} >>> >>> >>> >>> (2) Now I want to simulate an unchanged page. Anthony wrote on >>> http://stackoverflow.com/questions/14515313/how-to- >>> modify-web2py-download-function-to-return-304-not-modified-in-case-the >>> how to change the header. I add the response.headers-lines with a *constant >>> *"Last-Modified" time and/or a *constant *"ETag" (I think every value >>> is allowed here). My hope has been that these modifications *would >>> prevent a reload* of the page. If this would be correct I would always >>> see the same time. But it did not work, regardless of the header >>> modifications the page reloads again once a second. >>> >>> def mytime(): >>> jetzt=str(request.now)[:19] >>> mtime = "Mi, 06 Aug 2014 08:11:00 GMT" # always the same time! >>> >>> *response.headers['Last-Modified'] = mtime* >>> >>> * response.headers['Pragma'] = 'cache' response.headers['Cache-* >>> *Control'] = 'private' response.headers['ETag'] = "123" # any value, >>> constant* >>> return dict(jetzt=jetzt) >>> >>> >>> My primary problem is: the LOAD helper (or an other command?) asks the >>> server periodically if there is a new content - and the server should >>> reload the page under program control. >>> >>> Is it possible to solve it using the response headers? >>> >>> The purpose of the request.now call is only to show whether the page >>> reloads or not. >>> >>> Regards, Martin >>> >>> - >>> >> > > -- Resources: - http://web2py.com - http://web2py.com/book (Documentation) - http://github.com/web2py/web2py (Source code) - https://code.google.com/p/web2py/issues/list (Report Issues) --- You received this message because you are subscribed to the Google Groups "web2py-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
