[Zope] how to invalidate an object in the cache?

[Marco Mariani]

On Sun, Jul 02, 2000 at 03:56:39PM +1000, Marc Boschma wrote:


> Sounds like you need to manipulate the expiry time for the objects. I'd
> suggest that that can either be done in the RESPONSE or via meta tags in the
> standard_html_header to mark the page and the image as non-cacheable.
> 
> I'm actually interested in a Guru's response on this as I will need to set
> the expiry explicitly to save load on the server for content that is
> dynamically generated but doesn't change often.


It would work, but I'd have to set up meta tags for LocalFS objects..



I've found a better kludge: when I call the index page, I pass a "refresh" variable along
the URL which contains the number of the modified image.

Within the index method, I then call:


       <dtml-call "REQUEST.set('id2',id+'_0.jpg')">
       <dtml-let img="store[id][id2]">

       <A HREF="imageForm?fnum=&dtml.url_quote-id;"><IMG
           SRC="<dtml-var "img.absolute_url()+['','?%s'%_.random.random()][REQUEST.get('refresh')==id]">"
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
           WIDTH="<dtml-var "img.width">"
           HEIGHT="<dtml-var "img.height">"
           ALT="&dtml-id;"></A>

       </dtml-let>


This way, the refreshed image is called with a trailing "?0.283759872" that tricks Netscape
to think it's a new object, and reloads.


This could work for you too, maybe.



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