[Zope-CMF] DCWorkflow: detecting changes to object

[Tres Seaver]

On Sat, 2003-06-21 at 03:27, Paul Winkler wrote:
> I've been tasked with creating a workflow that sends an email
> notification anytime an object is created or changed by ftp 
> or webdav upload. This workflow is not used for anything other
> than triggering these emails.
> 
> I've handled creation successfully, by creating two states
> ("new" and "notification sent"), and an automatic transition
> from the former to the latter.  The transition ("notify")
> has as its guard expression "python:1", and after the state
> change it calls a script that sends email.  "new" is set as
> the initial state.
> 
> That works just fine. But it seems that re-upload of an existing 
> object counts as modification, not delete & create.  So 
> in this case, the email is not sent - and we need it to be sent.
> 
> I think what I need is a guard expression that says something like
> "Trigger this transition if the object's modification time is
> less than the last time I triggered this transition for this object."  
> But I can't figure  out how to do that.  Any suggestions?

1) Use a WorkflowMethod wrapper for PUT:

    from Products.CMFCore.WorkflowCore import WorkflowMethod
    ...

    def PUT( self, REQUEST, RESPONSE ):
        ....
    PUT = WorkflowMethod( PUT )

    Then, add a "modify" transition to your workflow, which both
    starts and ends in the 'notification sent' state.

2) Use the catalog as an event channel:  register a custom index whose
   only job is to leverage the calls to 'indexObject' to send your
   e-mail.

Tres.
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Tres Seaver                                tseaver@zope.com
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