Philipp von Weitershausen wrote:

Alek Kowalczyk wrote:
Hello again,
I have a rather big tree of MyObjects. MyObjects are adaptable to
hurry.workflow's IWorklowState. Now I'd like to create a catalog to index all MyObjects by their current states. How to do that? An option might be(?) to add to MyObject property like that:
@property
def currentState(self): return IWorkflowState(self).getState()
and index this property. But I'm not sure whether it is elegant solution, as it requires the object to know that it has workflow and (too) strong link between object and adapter.

Right. Fortunately, indexes know how to adapt. So, in order to index the workflow state of your objects, configure a FieldIndex (or ValueIndex from zc.catalog) to the IWorkflowState interface. Specify the 'getState' attribute and check the 'callable' option (because it's a method).

When encountering an object to be indexed, the FieldIndex (or ValueIndex) will then try to adapt it to IWorkflowState. If that succeeds (and it will for your MyObjects), it will call the getState () method on that adapter and index the return value.

That worked for me with zope.app.catalog:

catalog = Catalog()
catalog[u'workflow_state'] = FieldIndex(interface=IWorkflowState, field_name='getState', field_callable=True)
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