-----Original Message----- From: Dieter Maurer [mailto:dieter@handshake.de] Sent: Thursday, June 08, 2000 10:21 PM To: a.wacknitz@francotyp.com Cc: zope@zope.org Subject: Re: [Zope] Q: Accessing ZSQL methods from Python
a.wacknitz@francotyp.com writes:
my question is what type or value is returned by a ZSQL method that is invoked from Python? ZSQL methods return "Shared.DC.ZRDB.Results.Results" instances. Such an instance essentially behaves like a sequence of objects each describing one result row. These objects have been set up such that a column value can be accessed as attribute with the column name. Thus, "results[i].column" gives the value of "column" of the i.th row. Yes, that works fine. But I need to know of NULL values.
How to determine, how "Null" values are recognized, is less a Zope than a database adapter question. I would expect, that most (if not all) database adapters will map SQL Null to None.
That was what I thought but at least ZODBC won't do this. What I have found out is, that repr(SQL NULL) == 'Missing.Value'.
However, even some well established SQL databases do not treat Null standards-conform but represent it as the empty string. Then, the database adapter has no chance to map this to None but must use '', too.
ZODBC won't do this either.
Dieter
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