[Zope] Trying to trap ConflictError

Stefan H. Holek stefan at epy.co.at
Tue Jul 4 11:02:07 EDT 2006

First, you should not - ever - catch a ConflictError. It is essential  
for ConflictErrors to be propagated to the ZPublisher.

Second, the conflict is detected at commit time, which happens at the  
very end of the REQUEST. This likely is a while after your method has  


On 4. Jul 2006, at 15:56, Jonathan wrote:

> I am trying to trap the following error:
> Traceback (innermost last):
>   Module Zope2.App.startup, line 173, in zpublisher_exception_hook
>   Module ZPublisher.Publish, line 121, in publish
>   Module Zope2.App.startup, line 240, in commit
>   Module transaction._manager, line 96, in commit
>   Module transaction._transaction, line 380, in commit
>   Module transaction._transaction, line 378, in commit
>   Module transaction._transaction, line 433, in _commitResources
>   Module ZODB.Connection, line 484, in commit
>   Module ZODB.Connection, line 526, in _commit
>   Module ZODB.Connection, line 554, in _store_objects
>   Module tempstorage.TemporaryStorage, line 200, in store
> ConflictError: database conflict error (oid 0x39b0, class  
> BTrees._OOBTree.OOBucket, serial this txn started with  
> 0x0366974da4fd2288 2006-07-04 13:33:38.669252, serial currently  
> committed 0x0366974da54d9fcc 2006-07-04 13:33:38.742942)
> in an external method, as follows:
>         folder = self.unrestrictedTraverse(TEMPFOLDERIMAGES, None)
>         try:
>                 folder.manage_addImage(imageId, imageData)
>         except:
>                 <handle error message and return gracefully code>
> But the try/except block is not catching the error! (the error  
> continues to show up in error_log)
> (note: I started by trying "except ConflictError:", but that was  
> not working, so I went to the bare try/except)
> The traceback does not show where the error originates in the  
> external method, but there is only one place where the external  
> methods writes to TemporaryStorage. Does this indicate that the  
> error is not bubbling up properly?
> Any ideas as to why the error trapping is not trapping?  (running  
> Zope 2.9.2, debug=on)

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