[Zope-Coders] ZODB question

[Chris McDonough]

Here's something from the CST docs that tries to explain it:

      Persistent objects which have references to other persistent
      objects in the same database cannot be committed into a mounted
      database because the ZODB does not currently handle
      cross-database references.

      "Internal" (RAM-based) session data containers are currently
      implemented as objects within (automatically) mounted ZODB
      databases.  For this reason, they are equivalent in operation to
      external session data containers which are placed in a manually
      mounted database.

      If you use an internal session data container or an external
      session data container that is accessed via a "mounted"
      database, you cannot store persistent object instances which
      have already been stored in the "main" database as keys or
      values in a session data object.  If you try to do so, it is
      likely that an 'InvalidObjectReference' exception will be raised
      by the ZODB when the transaction involving the object attempts
      to commit.  As a result, the transaction will fail and the
      session data object (and other objects touched in the same
      transaction) will fail to be committed to storage.

      If your "main" ZODB database is backed by a nonundoing storage,
      you can avoid this condition by storing session data objects in
      an external data container instantiated within the "main" ZODB
      database.  If this is not an option, you should ensure that
      objects you store as values or keys in a session data object
      held in a mounted session data container are instantiated "from
      scratch" (via their constructors), as opposed to being "pulled
      out" of the main ZODB.


----- Original Message -----
From: "Andreas Jung" <andreas@andreas-jung.com>
To: <zope-coders@zope.org>
Sent: Sunday, February 17, 2002 8:27 AM
Subject: [Zope-Coders] ZODB question


> What's the meaning of the following error message ?
>
> Error Type: InvalidObjectReference
> Error Value: Attempt to store an object from a foreign database connection
>
> Andreas
>
>
>
>
>
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