#32526: Class based custom template filters seem to be broken since Django 2.0
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Reporter: 884756834 | Owner: nobody
Type: Bug | Status: new
Component: Template system | Version: 3.1
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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Description changed by 884756834:
Old description:
> In Django 1.10, writing a custom template filter using a class used to
> work:
>
> {{{
> #!div style="font-size: 80%"
> Code highlighting:
> {{{#!python
> class MyCustomFilter(object):
> __name__ = 'custom_filter'
>
> def __call__(self, value):
> if not isinstance(value, str):
> return value
>
> return MyHelperClass(value).do_stuff()
>
> def custom_filter = MyCustomFilter()
> }}}
> }}}
>
> But in Django 2.2 (and likely from 2.0 to 3.1) this seems to raise an
> error:
>
> {{{django.template.exceptions.TemplateSyntaxError: "requires 2 arguments,
> 1 provided"}}}
>
> I believe it is caused by the changes in one of, or both, these 2
> commits:
>
> https://github.com/django/django/commit/c2a1af883e18b93a77080650feb9e959536d51ca
> https://github.com/django/django/commit/620e9dd31a2146d70de740f96a8cb9a6db054fc7
>
> As a workaround, I've been able to rewrite it:
>
> {{{
> #!div style="font-size: 80%"
> Code highlighting:
> {{{#!python
> def custom_filter(value):
> if not isinstance(value, str):
> return value
>
> return MyHelperClass(value).do_stuff()
> }}}
> }}}
New description:
In Django 1.10, writing a custom template filter using a class used to
work:
{{{
#!div style="font-size: 80%"
Code highlighting:
{{{#!python
class MyCustomFilter(object):
__name__ = 'custom_filter'
def __call__(self, value):
if not isinstance(value, str):
return value
return MyHelperClass(value).do_stuff()
custom_filter = MyCustomFilter()
}}}
}}}
But in Django 2.2 (and likely from 2.0 to 3.1) this seems to raise an
error:
{{{django.template.exceptions.TemplateSyntaxError: "requires 2 arguments,
1 provided"}}}
I believe it is caused by the changes in one of, or both, these 2 commits:
https://github.com/django/django/commit/c2a1af883e18b93a77080650feb9e959536d51ca
https://github.com/django/django/commit/620e9dd31a2146d70de740f96a8cb9a6db054fc7
As a workaround, I've been able to rewrite it:
{{{
#!div style="font-size: 80%"
Code highlighting:
{{{#!python
def custom_filter(value):
if not isinstance(value, str):
return value
return MyHelperClass(value).do_stuff()
}}}
}}}
--
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Ticket URL: <https://code.djangoproject.com/ticket/32526#comment:2>
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