Question

In Plone adding a member variable in a view class instance automatically makes it a part of view acquisition chain. The problem is described in detail here:

http://collective-docs.readthedocs.org/en/latest/views/browserviews.html#views-and-automatic-member-variable-acquisition-wrapping

What is the suggested approach for dealing with this problem

• Can we have Plone main template based views without implicit acquisition

• How about viewlets and portlet renderers then?

• If not… how one should deal with the problem so that self.xxx variables do not get extra acquisition wrapping?

Answer 1

Use Acquisition.aq_inner() to strip away the extra wrapping and restore the object to it’s original path. Please, do not use the single-item list approach as described in the document you link to.

To show one example from the linked document, but corrected with aq_inner():

from Acquisition import aq_inner

self.obj = self.context.reference_catalog.lookupObject(value)
return aq_inner(self.obj).absolute_url() # Acquistion chain corrected

Alternatively, you can use the aq_inner attribute:

self.obj = self.context.reference_catalog.lookupObject(value)
return self.obj.aq_inner.absolute_url() # Acquistion chain corrected

but that only works on objects that inherit from Acquisition.Explicit or Acquisition.Implicit; the aq_inner() function returns the passed argument verbatim if it is not a Acquisition-wrapped object.