[Zope-CMF] DirectoryViewSurrogate as context in FSPageTemplates

Enrique Perez eperez at yaco.es
Sun Jun 27 11:53:46 EDT 2010


Here in Yaco, while migrating a plone-2.0 site to plone-4.0, we've hit a 
problem with FSPageTemplates that live within a DirectoryViewSurrogate 
(within a DirectoryViewSurrgate within a ...) whithin a DirectoryView. 
The problem is that such a template gets as context the 
DirectoryViewSurrogate whithin which it lives, and that such an object 
doesn't get in its aq_inner.aq_parent chain the "real" context object on 
which the template is called. As a consequence, browser components that 
get rendered in macros surrounding or within the template get an 
unexpected context, and bad things happen such as totally wrong 
breadcrumbs, portlets not getting found by managers, wrong css class for 
the body element of the produced html, etc.

My investigations, greatly helped by Hanno Schlichting (thanks again, 
Hanno) on the plone-dev list, have led me to think that the problem lies 
in the pt_getContext method of 
Products.CMFCore.FSPageTemplate.FSPageTemplate. This method is directly 
got from Products.PageTemplates.ZopePageTemplate.ZopePageTemplate. IMHO, 
that method makes sense in a PageTemplate living in the zodb, but not in 
nested directories in the filesystem. So my proposed solution goes 
through giving a special pt_getContext method to FSPageTemplate. The 
requirements of that method would be:

  * Provide a context that is the innermost DirectoryViewSurrogate, with 
an aq_inner.aq_parent chain that directly passes from it to the "real" 
context object on which the template is called. This way, "navigational" 
elements such as the breadcrumbs get a proper path.

  * Provide the intermediate DirectoryViewSurrogates in the aq_chain of 
the final context. This way, if the FSPageTemplate relies by acquisition 
on scripts or zsql methods or thigs like that that live in those 
intermediate DVS, it will find them.

  * Apply a similar logic to the container variable in the template? not 
so sure about this, my stuff works with and without the c['container'] 
modification, so I have commented it out in the method below.

with this, I have come up with the following method for 

from Products.CMFCore.interfaces import IDirectoryView
from Acquisition import aq_inner, aq_chain, aq_parent, aq_base


     zpt_pt_getContext = ZopePageTemplate.pt_getContext.im_func

     def pt_getContext(self, *args, **kwargs):
         c = self.zpt_pt_getContext(*args, **kwargs)
         if IDirectoryView.providedBy(c['context']):
             context = c['context']
             for obj in aq_chain(context):
                 if not IDirectoryView.providedBy(obj):
                     context = aq_base(context).__of__(obj)
             #c['container'] = 
             c['context'] = c['here'] = context.__of__(c['container'])
         return c

(In my thunderbird getting the list from gmane the formatting gets 
right, but just in case, I attach a diff file).

I have run the CMFCore tests on a 
buildout (not sure if it's the right place to run them) and they give 
the same results with and without the patch, and commenting out or not 
the container modification in the patch:

eperez at gallina$ ./bin/instance test -s Products.CMFCore
Error in test test_copy_cant_create_target_metatype_not_supported
Error in test test_move_cant_create_target_metatype_not_allowed
Error in test test_move_cant_create_target_metatype_not_supported
Total: 610 tests, 0 failures, 3 errors

So, questions:

Does this sound right? Is someone else encountering similar problems? If 
the answer to the previous questions are yes and (yes or not), what 
should be my next step?

Thanks for getting this far in this rather longish post.

Best regards,

Enrique Pérez Arnaud <eperez at yaco.es>
Yaco Sistemas SL| http://www.yaco.es
C/ Rioja 5, 41001 Sevilla (España)
Tel: (+34) 954 50 00 57
Fax 954 50 09 29
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