[Zope] Newbie question: ZCatalog 'summary' meta-data

[Tres Seaver]

Curtis Matthews <cmatthews@cpcus.com> wrote:

> Please find it in your heart to enlighten a newbie. :)
> 
> I've been able to find a lot of helpful documentation about how to use
> ZCatalogs and search interfaces, but one thing that has eluded me is the
> 'summary' meta-data feature. All I've been able to find out about this is
> it's supposed to store the first few hundred characters of a text document
> so that they can be displayed on a results report.
> 
> I now have a catalog of about 100+ DTML Documents, and every time I search
> it, the "summary" column of the results report is empty. I'm confused. I
> assumed ZCatalog builds this summary automatically...does it? If not, what
> extra stuff do I have to do to make it so?
> 
> Any troubleshooting suggestions would be appreciated.

The catalog has index for 'summary', because CatalogAware objects expose a
'summary' attribute (a method, actually) which performs as you describe. 
Unfortunately, DTMLDocument is *not* dervied from CatalogAware, and so has no
such method.  This gap accounts for other infelicitous (non)interaction between
DTMLDocuments and ZCatalogs:  DTMLDocuments are not automagically added/removed
from the catalog when they are created/deleted, for instance.

A workaround is to add a PythonMethod or ExternalMethod named 'summary' as a
peer of your Catalog, defined so (assuming an EM):

    def summary( self, num=200 ):
        """Return a summary of the string form of the object."""
        text=str( self )
        n=min(num, len(text))
        return text[:n]

Note that the "string form" of a DTML document is the unrendered source, which
may not be very useful to look at -- most will start off with '<dtml-var
standard_html_header>...' and go downhill from there.  You can, of course, tweak
the summary code to return any property, or even a concatenated set of
properties (like PrincipiaSearchSource does).

Tres.
-- 
=========================================================
Tres Seaver  tseaver@digicool.com   tseaver@palladion.com