Diazo, parameters and restrictedTraverse - plone

Question

if in my diazo controlpanel > 'Parameter expressions' I put
have_left_portlets = python:context and context.restrictedTraverse('##plone').have_portlets('plone.leftcolumn',context)
I obtain an error only when I'm on the portal homepage:
2012-06-26 16:51:42 ERROR plone.transformchain Unexpected error whilst trying to apply transform chain
Traceback (most recent call last):
File "/Users/vito/.buildout/eggs/plone.transformchain-1.0.2-py2.6.egg/plone/transformchain/transformer.py", line 48, in __call__
newResult = handler.transformIterable(result, encoding)
File "/Users/vito/.buildout/eggs/plone.app.theming-1.0-py2.6.egg/plone/app/theming/transform.py", line 257, in transformIterable
params[name] = quote_param(expression(expressionContext))
File "/Users/vito/.buildout/eggs/Zope2-2.13.13-py2.6.egg/Products/PageTemplates/ZRPythonExpr.py", line 48, in __call__
return eval(self._code, vars, {})
File "PythonExpr", line 1, in <expression>
File "/Users/vito/.buildout/eggs/AccessControl-2.13.7-py2.6-macosx-10.6-x86_64.egg/AccessControl/ImplPython.py", line 675, in guarded_getattr
v = getattr(inst, name)
AttributeError: 'FilesystemResourceDirectory' object has no attribute 'restrictedTraverse'
How I can solve this?

Answer 1

I suspect this is a bug in plone.app.theming: the context isn't set correctly. Strange, though.

Answer 2

Just confirming that the issue exits:
I get about the same traceback, the site itself looks fine, but for every click inside the site I get a the following traceback in my instance fg:
2012-08-10 15:05:05 ERROR plone.transformchain Unexpected error whilst trying to apply transform chain
Traceback (most recent call last):
File "/opt/etc/buildout/eggs/plone.transformchain-1.0.2-py2.6.egg/plone/transformchain/transformer.py", line 48, in __call__
newResult = handler.transformIterable(result, encoding)
File "/opt/etc/buildout/eggs/plone.app.theming-1.0-py2.6.egg/plone/app/theming/transform.py", line 257, in transformIterable
params[name] = quote_param(expression(expressionContext))
File "/opt/etc/buildout/eggs/Zope2-2.13.10-py2.6.egg/Products/PageTemplates/ZRPythonExpr.py", line 48, in __call__
return eval(self._code, vars, {})
File "PythonExpr", line 1, in <expression>
AttributeError: 'FilesystemResourceDirectory' object has no attribute 'Language'
This is because I have the following line in my manifest.cfg (which is about the same as the parameter line in the plone_control_panel:
lang = python: context.Language()
In a way in my case this is sort of logical, since not all content objects have an index called Language().
But the 'context' in this case is apparently refering to the 'FileSystemResourceDirectory' and not to the piece of content you are on?
I'll try with pdb if I can find some more info...