Christian Heimes wrote at 2005-4-1 22:28 +0200:
... You want to bind some actions to the transaction system because you want to execute some code at the end of the first phase of the 2 phase commit.
I do not think that Florent wants to execute things at the end or in the first commit phase. Instead, he wants to execute something *BEFORE* this phase.
Hooking into the transaction machinery of ZODB is very easy. Write your own DateManager implementing the IDateManager interface and register it into the current transaction using get_transaction.register(DM).
For your use case overwrite the tpc_vote() method of the data manager to do the indexing at the boundary between the two phases.
This will not work for Florent's use case, at least not in the current ZODB (for Zope 2.7). Reason: The transaction freezes the set of objects it processes in the commit *BEFORE* the first commit phase. Therefore, no "tpc_vote" is allowed to modify any persistent object. Failure to do so leads to extremely nasty persistency errors (the object is marked changed but no transaction knows about it -- no change to this object in the future will get persisted until a restart).
Jens Vagenpohl's mail host and Chris McD's blob have example code for you.
But they do not change persistent objects (at least, I hope so). -- Dieter