At 10:30 09/11/99 , Rik Hoekstra wrote:
Today I was experimenting a little with inserting and deleting from lines properties (though I see no reason why this would not apply to other properties. There was some strange behavior with modifying lists from dtml. The method was as follows:
<dtml-var lst>
<dtml-call "lst.remove(REQUEST['remove_item'])">
<dtml-var lst>
where lst is a property of the containing folder. The proper way to do this would be to make a local copy of the list and replacing the property with it, but that's not the point.
Now, as far as I'm aware this method should have no effect on the properties of the folder, or is it. But is has: it changes the property and it seems to have a permanent effect. But, as it is not a completed transaction changes are undone if ZServer is closed down.
A few questions: - has anyone seen this as well - could someone explain me how this works - is this a bug or a feature - if it is a feature - could someone show me its use
You are modifying a mutable list, something the ZODB doesn't detect. This is a documented shortcoming of the Persistence mechanism. If you make a copy of the list, and put that copy back using editProperties or some such API method, the change will be detected and made persistent. -- Martijn Pieters, Web Developer | Antraciet http://www.antraciet.nl | Tel: +31-35-7502100 Fax: +31-35-7502111 | mailto:mj@antraciet.nl http://www.antraciet.nl/~mj | PGP: http://wwwkeys.nl.pgp.net:11371/pks/lookup?op=get&search=0xA8A32149 ------------------------------------------