CODEWITHSUNDEEP
pythonconditional-statements
Reto Tschuppert
Reto Tschuppert

Reputation: 11

TAL condition using not does evaluate as I expect

I have the following program rendering a very simple page.

from chameleon import PageTemplate

template_content = """
<html>
  <head>
    <title>${title}</title>
  </head>
  <body>
    <h1 tal:condition="people.show_people and people.persons|False">People</h1>
    <p tal:repeat="name people.persons">${name}</p>
    
    <h2 tal:condition="not people.not_existing_prop|False">Condition People non-existing prop</h2>
    <h3 tal:condition="not prop" tal:define="prop people.non_existing_prop|False">Define People non-existing prop</h3>
  </body>
</html>
"""

template = PageTemplate(template_content)

people = {'show_people': True, 'persons': ['Rudi', 'Fritz']}
variables = {'title': 'Try to provoke TAL condition bug', 'people': people}

output = template(**variables)
print(output)

I can't figure out why tag in line 12 does not show up on the rendered html result. Why doesn't my condition condition="not people.not_existing_prop|False" evaluate to True?

Asone see on line 13, tag, I found a workaround using 'define' but I still want to understand why line 12 behaves different than I expected it.

Upvotes: 0

Views: 28

Answers (0)

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