----- Original Message ----- From: "Stefan H. Holek" <[EMAIL PROTECTED]>
To: "Jonathan" <[EMAIL PROTECTED]>
Cc: <zope@zope.org>
Sent: Tuesday, July 04, 2006 11:02 AM
Subject: Re: [Zope] Trying to trap ConflictError

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

This seems to be an extremely 'user-unfriendly' approach.

In my use case the error is being generated when an image object is being written to a temporary folder. If, for any reason, the image object is not able to be stored it would seem prudent to be able to handle this condition within the application software.

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 executed.


Ok, this I can understand. Is there any kind of 'post processing' mechanism/hooks that would enable application level software (external methods) to check for and handle errors at this point?


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)
                folder.manage_addImage(imageId, imageData)
                <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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