#22767: Unexpected value for an unset variable with length filter in templates
---------------------------------+--------------------------------------
Reporter: Walkman | Owner: nobody
Type: Bug | Status: new
Component: Template system | Version: 1.6
Severity: Normal | Resolution:
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Changes (by gchp):
* needs_better_patch: => 0
* needs_tests: => 0
* needs_docs: => 0
Comment:
I agree that this is somewhat unexpected, though I don't know if it's a
bug. If you were to do the same in Python, and tried to get the length of
something which is None, you would get a TypeError. To get around that you
would either use a try/except block, or first check if the variable is not
None. I think it's reasonable to do the same in your templates. ie:
{{{
{% if groups %}
{% if groups|length > 0 %}
groups!
{% else %}
no groups :(
{% endif %}
{% else %}
groups not defined
{% end %}
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/22767#comment:1>
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