[Zope3-Users] querying the catalog

[Duncan McGreggor]

I have a multiple sites on a zope3 instance (folders at the top level 
that have their own site managers). In one of them, there is page 
content object with a custom view for portraying search results from 
its (local) catalog. However, I have had a great deal of difficulty 
getting the catalog I want. Here is the pertinent code for three 
attempts, the last of which "worked".

Attempt #1

class HomePageView(BrowserView):
     def inventoryInStock(self):
         catalog = zapi.getUtility(ICatalog,
             name='accumac_catalog',
             context=self.context)
         return catalog.searchResults(equipment_in_stock=[True])

Attempt #2

class HomePageView(BrowserView):
     def inventoryInStock(self):
         sm = zapi.traverse(self.context, '++etc++site')
         catalog = sm['default']['accumac_catalog']
         return catalog.searchResults(equipment_in_stock=[True])

Attempt #3

class HomePageView(BrowserView):
     def inventoryInStock(self):
         sm = zapi.traverse(self.context, '/accumac/++etc++site')
         catalog = sm['default']['accumac_catalog']
         return catalog.searchResults(equipment_in_stock=[True])


The first attempt got the catalog at the root of the zope 3 instance if 
I passed no name; if I passed the name of the local catalog, I got the 
following error:

ComponentLookupError: (<InterfaceClass 
zope.app.catalog.interfaces.ICatalog>, 'accumac_catalog')

A clue as to why this happened may be in attempt #2. The error for 
attempt #2 was:

TraversalError: (<accumacsite.homepage.HomePage object at 0x2e688f0>, 
'site')

And this might be a clue; it made me think that if the HomePage content 
object was traversable, in both attempt #1 and #2, the correct catalog 
would have been found.

In attempt #3, I had zope traverse to the absolute location of the 
local site manager, and from there got the correct catalog, with the 
results being returned properly. However, this last attempt seems 
rather hackish, as it uses a path and hard-coded names. I'd really like 
to do this the right way.

Does anyone have advice on this?

Thanks!

Duncan