Add "tag" method to ATEvent - plone

Question

I use archetypes.schemaextender to extend the schema of ATEvent in order to add an ImageField.
That works.
Now, I want to add the "tag" method to the ATEvent in order to use the "new" way of scaling images.
So I do this :
In a file extender.py :
from Products.CMFCore.permissions import View
from AccessControl import ClassSecurityInfo
from zope.interface import Interface
class IImageExtender(Interface):
""" """
def tag():
""" """
class ImageExtender(object):
""" """
implements(IImageExtender)
security = ClassSecurityInfo()
def __init__(self, context):
self.context = context
security.declareProtected(View, 'tag')
def tag(self, **kwargs):
"""Generate image tag using the api of the ImageField
"""
return self.getField('image').tag(self, **kwargs)
After that in the configure.zcml:
<adapter for="Products.ATContentTypes.interface.IATEvent"
provides=".extender.IImageExtender"
factory=".extender.ImageExtender" />
But it doesn't work.
I get those errors :
Module zope.tales.pythonexpr, line 59, in __call__
- __traceback_info__: ( path('nocall:item_object/tag')(scale=size, css_class='tileImage'))
Module <string>, line 1, in <module>
Module zope.tales.pythonexpr, line 77, in __call__
Module zope.tales.expressions, line 217, in __call__
Module zope.tales.expressions, line 194, in _eval
Module zope.tales.expressions, line 217, in __call__
Module zope.tales.expressions, line 194, in _eval
Module zope.tales.expressions, line 124, in _eval
Module zope.pagetemplate.engine, line 66, in __call__
Module zope.traversing.adapters, line 136, in traversePathElement
- __traceback_info__: (<ATEvent at /Plone/manifestations/visites-conferences/conf>, 'tag')
Module zope.traversing.adapters, line 50, in traverse
- __traceback_info__: (<ATEvent at /Plone/manifestations/visites-conferences/conf>, 'tag', [])
LocationError: (<ATEvent at /Plone/manifestations/visites-conferences/conf>, 'tag')
Any clues ?
Thanks.

Answer 1

I believe the problem here is that you are trying to call 'tag' on the ATEvent
Object, but the method is defined on an adapter for the ATEvent Object. You need to be able to call IImageExtender(item).tag()
Unfortunately, restricted python prevents you from doing this directly in a page template, so your best bet will be to create a BrowserView for your extended ATEvent that provides access to the adapter.