Nice Nice, i 'll add this to my django reference sheet
On Dec 6, 3:34 pm, Empty <[EMAIL PROTECTED]> wrote:
> Nice info. This was just asked on the IRC channel a couple nights
> ago. I'll be sure to pass it on.
>
> Michael Trier
> blog.michaeltrier.com
>
> On Dec 5, 2007 7:09 PM, Michal Ludvig <[EMAIL PROTECTED]> wrote:
>
>
>
> > Michal Ludvig wrote:
>
> > > for the project I'm working on I needed to create a custom template tag,
> > > call it 'mytag'.
>
> > > If I use it as {% mytag something %} everything goes fine (where
> > > 'something' is a string passed to the template).
> > > However I can't add any filters to that 'something'. As soon as I do:
> > > {% mytag something|upper %}
> > > I get an exception:
> > > VariableDoesNotExist at /test/
> > > Failed lookup for key [something|upper]
>
> > > That leads to a code in MytagNode.render() method:
> > > actual_message = resolve_variable(self.message, context)
> > > where self.message is the argument passed to the macro, in this case
> > > it's a string 'something|upper'.
>
> > > Is there an easy way to run all the attached filters in MytagNode?
>
> > For the record:
> > There is a FilterExpression class in django.template that does exactly
> > what I need. So for the tag implementation, instead of:
>
> > ===
> > from django.template import resolve_variable
>
> > @register.tag
> > def mytag(parser, token):
> > tag_name, message = token.split_contents()
> > [...]
> > return MytagNode(message)
>
> > class MytagNode(template.Node):
> > [...]
> > def render(self, context):
> > actual_message = resolve_variable(self.message, context)
> > [...]
> > ===
>
> > I do it like this:
>
> > ===
> > from django.template import FilterExpression
>
> > @register.tag
> > def mytag(parser, token):
> > [...]
> > filter_expression = FilterExpression(message, parser)
> > return MytagNode(filter_expression)
>
> > class MytagNode(template.Node):
> > [...]
> > def render(self, context):
> > actual_message = self.filter_expression.resolve(context)
> > [...]
> > ===
>
> > The filter_expression.resolve(context) runs all the filters attached to
> > the variable and things work as expected. The 'parser' argument even
> > makes it aware of custom filters loaded through {% load ... %} tags.
>
> > Lesson learned, note taken.
>
> > Michal
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