[Zope] problem with dtml-var displaying None for NULL from po stgres

[Farrell, Troy]

Chances are (I haven't verified this yet) that PoPy and ZPoPyDA don't set
the variable if it isn't there in PostgreSQL. Try:

<dtml-var variable missing>

Troy

-----Original Message-----
From: Chris Kratz [mailto:chris.kratz@vistashare.com]
Sent: Tuesday, June 05, 2001 4:05 PM
To: zope@zope.org
Subject: [Zope] problem with dtml-var displaying None for NULL from
postgres


Hello all,

Up until this week, we were running Zope on a windows ME box against an
access database using ODBC for our first stage of development.  Now, I have
migrated the database and the zope instance over to a Linux box running Red
Hat 7.1, Zope 2.3.2, Python 1.5.2, PostgreSQL 7.1, with the PoPy
2.0.1/ZPoPyDA 1.2 connecting everything up and we are running successfully.

My question is this: we have quite a large number of pages where we use the
<dtml-var> tag to dump a field from the database (after a select).  On the
previous setup, when the field was NULL in the database, the var tag happily
did nothing.  Now, on the new server, if a Null is found, it prints out None
instead of nothing.  For now, I am manually modifying the pages and wrapping
each of the var tags with an if tag like this: <dtmil-if field><dtml-var
field></dtml-if> which gives the expected behavior.  This works, but is time
consuming.

I have examined each of the pieces (Zope/ZPoPyDA/PoPy/PostgreSQL) and cannot
find an easy way to change this behavior.  After reading some related
information on the mailing list, I think the culprit is most likely the DA.
Unfortunately, I was not successfull in installing the psycopg DA and the
current version of egenics mxDateTime so I cannot compare the two DA's
(ZPoPyDA and psycopgDA).

Is this expected behavior?  Is the Zope 2.3.2, Python 1.5.2, ZODBCDA,
MSAccess configuration simply different in some aspect?  Why are we getting
different behaviors with everything the same except a different database?
If there is no way around this, is there a faster/better way to modify the
pages so that they don't display anything for a NULL field?

Thanks for your help,

-Chris


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