I favor raising an exception in this case, because values in this context are
not coerced to strings (unlike the case in {{ }} references).
IMO, and in order to protect the writers of all 3rd-party filters, the only way
to solve this without raising an exception is to resolve the whole filter
expression to string_if_invalid, rather than just the missing var.
Shai
On Thursday 01 June 2017 03:10:39 Jon Dufresne wrote:
> Just my opinion, but I think raising an exception is more helpful to
> developers and will result in fewer unnoticed bugs.
>
> More generally, I know the template engine has a history of silently
> converting unknown variables to string_if_invalid but this is more harmful
> than helpful in my experience. It continues to be a source of hard to catch
> bugs on the projects I work on. So I'd prefer we avoid introducing more of
> this pattern if possible.
>
> On Wed, May 31, 2017 at 8:03 AM, Tim Graham <timogra...@gmail.com> wrote:
> > Should nonexistent template filter arguments raise an exception? Current
> > behavior:
> >
> > {{ value|filter:nonexistent_template_var}}
> >
> > raises VariableDoesNotExist for nonexistent_template_var.
> >
> > I guess the proposal would be to make nonexistent_tempatle_var resolve to
> > string_if_invalid. As for me, I think the current behavior is less error
> > prone.
> >
> > Related tickets:
> >
> > https://code.djangoproject.com/ticket/13167
> > This was first closed incorrectly as "fixed" by Jacob (actually a
> > different issue was fixed), then amended as wontfix by Karen with the
> > note, "I'm fine with wontfixing that, though it does rather seem to go
> > against "template errors don't raise exceptions" philosophy."
> >
> > https://code.djangoproject.com/ticket/28172
> > A follow up ticket requesting the same thing as #13167.
> >
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