[Zope-dev] ZCatalog searching for missing values

[Stephan Richter]

>We've installed Kavio's CatalogQuery product and are very happy with it.
>Haven't looked at the ZOQLMethod from iuveno yet, but both look like
>great steps in the right direction.

Thanks.

I actually need to look at Casey's code and see what I can reuse. The 
efficiency of my version is not that great yet, but much more flexible. So 
I want to take Casey's code and optimize mine a little.

BTW, I just added a mailing list and a poll for ZOQL. Please go to 
http://demo.iuveno-net.de/iuveno/Products/ZOQLMethod and vote in the poll, 
so I can get an estimate of the general interest.

>I have one question: is it possible using a normal catalog query or
>Kavio's catalog query to check if a value is not set?  The
>representation returned is Missing.Value, but I seem to be unable to
>say, e.g, 'Description == Missing.Value' etc.  How hard is it to add
>such functionality?

You mean, whether the system checks, if a property exists at all or is set 
to None? I think both would be no problem.

1. Property exists or not:

I could support a function, like: exists(Property)
Example:

SELECT *
   FROM Test
   WHERE exists(Property);

2. Property is set to None:

Simply use equal: Property == None
Note: That might work already? I have to check...
Example:

SELECT *
   FROM Test
   WHERE Property == None;

Regards,
Stephan

--
Stephan Richter
CBU - Physics and Chemistry Student
Web2k - Web Design/Development & Technical Project Management