[Zope-dev] [BlueBream] Reg. persisting data in ZODB via forms

[Laurence Rowe]

On 9 June 2011 07:12, Joshua Immanuel <josh at hipro.co.in> wrote:
> Hello Jonah,
>
> On Wed, 2011-06-08 at 22:25 -0700, Jonah Crawford wrote:
>> Ah yes you do that in the zcml right after you define your object in a
>> class :)
>
> I am not aware of the zcml configuration that can mark a class as
> persistent. If you could explain, it would be helpful.

ZCML is not relevant here.

>> On Jun 8, 2011, at 10:23 PM, Joshua Immanuel wrote:
>> > I was trying to add a non persistent object to the BTreeContainer. I
>> > was of the notion that I don't need to make my object persistent
>> > explicitly, as I am adding it to the persistent btree container. The
>> > add operation was successful but the modify operation on my object
>> > failed to persist.
>> > Making my object persistent solved the issue.
>
> I derived my class from persistent.Persistent in order to make it
> persistent.

Deriving your class from Persistent is normally the right choice.
Storing immutable non-persistent objects such as strings, ints, floats
or tuples of them also works without surprises. Storing mutable
non-persistent objects in the ZODB is considered advanced usage and
you must inform the persistence machinery on any modification. The
best way to do this is to re-assign the non-persistent object to it's
parent persistent object, causing the parent to be marked as modified.

Laurence