[ZODB-Dev] strange commit error

[Miles]

Hi,

Thanks for your help

<snip>

>>
>>    (from ZODB.serialize.py - line 350)
>>
>>            if obj._p_jar._implicitlyAdding(oid):
>>                raise InvalidObjectReference(
>>                    "A new object is reachable from multiple  
>> databases. "
>>                    "Won't try to guess which one was correct!"
>>                    )
>>
>> Can anyone shed any light on what this error means?!
> 
> It means a new object is referenced from objects in multiple databases  
> and it doesn't know what database to assign it to.

After some digging into the objects, I think I understand this.  It's 
come up as follows:

  - I load object A from the old database
  - Object A has an attribute B, which is an object also in the old database
  - I create a fresh copy of A, but leave the attribute B remained a 
reference to B in the old database
  - When I went to commit A, I got an error because A.B points to the 
old database still

Is this right?

> 
>>  Given a persistent
>> object, what is the correct way to get a completely fresh copy that is
>> not tied to any database at all, so I can transfer these old objects  
>> to
>> the current database.
> 
> I would use the database export/import API to export it from one  
> database and import it to another. (There are issues with doing this  
> in Zope 3, but I assume you're using Zope 2.

Sorry if I'm being thick - I thought the code below did indeed use the 
export/import API:

          f=tempfile.TemporaryFile()
          old_ob._p_jar.exportFile(old_ob._p_oid,f)
          f.seek(0)
          container = app.new_folder
          ob=container._p_jar.importFile(f)

Is this what you meant?  If so, I'll do some more digging.

Thanks,

Miles