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Products.PageTemplates (with chameleon): bad comment handling #716

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d-maurer opened this issue Oct 24, 2019 · 6 comments · Fixed by zopefoundation/z3c.pt#18
Closed

Products.PageTemplates (with chameleon): bad comment handling #716

d-maurer opened this issue Oct 24, 2019 · 6 comments · Fixed by zopefoundation/z3c.pt#18
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@d-maurer
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Some comments are badly handled.

This works

>>> from Products.PageTemplates.PageTemplate import PageTemplate
>>> pt = PageTemplate()
>>> pt.pt_edit(r'''
... <html xmlns:tal="http://xml.zope.org/namespaces/tal"><body>
... <div tal:content="string:1" />
... <!--
...         <div tal:repeat="si stock_items">
...           <a tal:attributes="href si"</a>
...       </div>
... --> 
... </body></html>''',
... "text/html"
... )
>>> pt()
'\n<html><body>\n<div>1</div>\n<!--\n        <div tal:repeat="si stock_items">\n          <a tal:attributes="href si"</a>\n      </div>\n--> \n</body></html>'

This does not:

>>> from Products.PageTemplates.PageTemplate import PageTemplate
>>> pt = PageTemplate()
>>> pt.pt_edit(r'''
... <html xmlns:tal="http://xml.zope.org/namespaces/tal"><body>
... <div tal:content="string:1" />
... <!--
...         <div tal:repeat="si stock_items">
...           <a tal:attributes="href string:${si/mid}"</a>
...       </div>
... --> 
... </body></html>''',
... "text/html"
... )
>>> pt()
Traceback (most recent call last):
  File "/home/dieter/tmp/xmlsec3/python/lib/python3.6/site-packages/chameleon/utils.py", line 405, in __getitem__
    return dict.__getitem__(self, key)
KeyError: 'si'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/dieter/tmp/xmlsec3/python/lib/python3.6/site-packages/chameleon/template.py", line 183, in render
    self._render(stream, econtext, rcontext)
  File "4ed89ab573418b650d2a190af61afb86.py", line 139, in render
  File "/home/dieter/tmp/xmlsec3/python/lib/python3.6/site-packages/chameleon/utils.py", line 407, in __getitem__
    raise NameError(key)
NameError: si

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/dieter/tmp/Zope/src/Products/PageTemplates/PageTemplate.py", line 103, in __call__
    return self.pt_render(extra_context={'options': kwargs})
  File "/home/dieter/tmp/Zope/src/Products/PageTemplates/PageTemplate.py", line 85, in pt_render
    showtal=showtal)
  File "/home/dieter/tmp/xmlsec3/python/lib/python3.6/site-packages/zope/pagetemplate/pagetemplate.py", line 135, in pt_render
    strictinsert=0, sourceAnnotations=sourceAnnotations
  File "/home/dieter/tmp/Zope/src/Products/PageTemplates/engine.py", line 88, in __call__
    return self.template.render(**kwargs)
  File "/home/dieter/tmp/xmlsec3/python/lib/python3.6/site-packages/z3c/pt/pagetemplate.py", line 158, in render
    return base_renderer(**context)
  File "/home/dieter/tmp/xmlsec3/python/lib/python3.6/site-packages/chameleon/zpt/template.py", line 305, in render
    return super(PageTemplate, self).render(**_kw)
  File "/home/dieter/tmp/xmlsec3/python/lib/python3.6/site-packages/chameleon/template.py", line 203, in render
    raise_with_traceback(exc, tb)
  File "/home/dieter/tmp/xmlsec3/python/lib/python3.6/site-packages/chameleon/utils.py", line 75, in raise_with_traceback
    raise exc
  File "/home/dieter/tmp/xmlsec3/python/lib/python3.6/site-packages/chameleon/template.py", line 183, in render
    self._render(stream, econtext, rcontext)
  File "4ed89ab573418b650d2a190af61afb86.py", line 139, in render
  File "/home/dieter/tmp/xmlsec3/python/lib/python3.6/site-packages/chameleon/utils.py", line 407, in __getitem__
    raise NameError(key)
NameError: si

 - Expression: "si/mid"
 - Filename:   <string>
 - Location:   (line 6: col 43)
 - Arguments:  template: <PageTemplate - at 0xb59fa78c>
               options: {...} (1)
               nothing: <NoneType - at 0x84687d0>
               request: <NoneType - at 0x84687d0>
               modules: <SimpleModuleImporter - at 0xb59fa92c>
               default: <object - at 0xb6bea8e0>
               repeat: {...} (0)
               loop: {...} (0)
               wrapped_repeat: <SafeMapping - at 0xb59fae8c>
               target_language: <NoneType - at 0x84687d0>
               translate: <function translate at 0xb5999974>

Apparently, sometimes, expressions in comments are (wrongly) evaluated.

This is almost surely a chameleon bug.
@d-maurer d-maurer added the bug label Oct 24, 2019
@d-maurer d-maurer mentioned this issue Oct 24, 2019
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@malthe
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malthe commented Oct 24, 2019

I'm pretty sure it's intentional: https://github.com/malthe/chameleon/blob/master/src/chameleon/zpt/program.py#L657

But if this is not Zope default behavior (and I'm guessing it's not), then it should be behind a feature gate. Then normally, that feature gate is disabled in the Zope integration (z3c.pt).

@d-maurer
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d-maurer commented Oct 24, 2019 via email

@malthe
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malthe commented Oct 24, 2019 •
edited
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Agreed. But the solution in this case is to comment using <!--?.

I agree that it might not be the best thought-through feature. But then again, commenting out TAL should be done using tal:condition="False". Or use the dedicated syntax: <!--?.

@d-maurer
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The current Zope switches from its own page template implementation to chameleon implicitly -- without being (explicitly) instructed to do so. I noticed the problem while migrating an old application to Zope 4. The affected template was never designed to be used with chameleon - thus it used standard HTML/XML commenting, not one of the special chameleon commenting forms. In this context, it seemed bizarre that (apparently) a tal:content was evaluated and caused a NameError while the enclosing tal:repeat defining this name was not.
I could well imagine that chameleon wants to be able to generate HTML/XML comments and thus processes the material inside the comment, but then it should execute both the tal:repeat as well as the tal:content. Thanks to your explanation, I now see that inside a (normal HTML/XML) comment, $<expression> is evaluated wherever it occurs - and those are the only evaluations inside the comment. Thus, chameleon did not evaluate the tal_content but only the contained $<expression>.

@malthe
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malthe commented Oct 25, 2019

Yeah that's exactly it. And as I mentioned, that "feature" should probably be put behind a configuration flag which is pretty easy to do. I'll see if I can find the time to set it up.

@malthe
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malthe commented Mar 24, 2020 •
edited
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This kind now be disabled using enable_comment_interpolation=False. When a new release of Chameleon is out, this can added to https://github.com/zopefoundation/z3c.pt/blob/master/src/z3c/pt/pagetemplate.py#L82.

d-maurer added a commit to zopefoundation/z3c.pt that referenced this issue Mar 31, 2020
@d-maurer
Fix zopefoundation/Zope#716
5faf8ac
@d-maurer d-maurer mentioned this issue Mar 31, 2020
Merged
dataflake pushed a commit to zopefoundation/z3c.pt that referenced this issue Mar 31, 2020
@d-maurer @dataflake
Fix zopefoundation/Zope#716
49e73a2
dataflake added a commit that referenced this issue Mar 31, 2020
@dataflake
- update to z3c.pt to fix #716
bdf93a6
dataflake added a commit that referenced this issue Mar 31, 2020
@dataflake
- update to z3c.pt to fix #716
4ccbdad
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Prevent interpolations in comments zopefoundation/z3c.pt
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@malthe @d-maurer