On Mon, 12 Feb 2007 05:50:32 +0000, Patrick J. Anderson wrote:
> On Mon, 12 Feb 2007 15:32:07 +1100, Malcolm Tredinnick wrote:
>
>> On Mon, 2007-02-12 at 03:49 +0000, Patrick J. Anderson wrote:
>>> I think I might be missing something, but I have a problem with
>>> date filter. Why doesn't this template code work?
>>>
>>> {% ifequal d|date:"l" "Sunday" %}
>>> <td class="sunday">
>>> {% else %}
>>> <td>
>>> {% endifequal %}
>>>
>>> <ul><li>{{ d|date:"l" }}</li></ul>
>>>
>>> But inside the HTML list item {{ d|date:"l" }} produces full weekday
>>> names.
>>
>> The Django resolver for template tags is a bit simple-minded about what
>> you can pass as arguments: basically either string literals or
>> references to variables in the template's context are permitted. What it
>> cannot do is taken something that is a context variable modified by a
>> filter and work out that value. So Django is failing quietly on the
>> first argument there and effectively comparing the empty string to the
>> string "Sunday", I suspect.
>>
>>> Can and should this evaluation be done in such a way, or perhaps
>>> there's a better way or no way this can be done using Django templates?
>>
>> Assuming this is related to your post from a few hours ago about
>> determining if it is the first day of the week, I cannot really think of
>> any way to do it with the default filters and template tags. A couple of
>> possibilities that spring to mind:
>>
>> (1) If your object had a "is first day of the week" method, you could
>> call that. I realise in this case you are probably passing in standard
>> Python datetime objects, in which case you are stuck, but maybe "d" is
>> something custom that you have control over and create a method that
>> returns a boolean.
>>
>> (2) Write a custom template tag that tests if the date is the first day
>> of the week (or equal to another date). It isn't too hard to write
>> custom tags and it really is the recommended way for any kind of
>> advanced functionality you want to make accessible through the template.
>> You could pass the "d" variable and the day of the week to the tag and
>> have it act like an if tag if the args were equal (copying the default
>> "if" tag from django/templates/defaulttags.py as a starting point is one
>> way to start here).
>>
>> Regards,
>> Malcolm
>>
>>
>>
>>
> Thanks, Malcolm. I see. I didn't know that a Django tag couldn't take a
> variable modified by a filter. Thanks for explaining that part. I'll try
> to come up with a custom template tag by looking at the docs and Django
> built-in tags in the file you mentioned.
>
> Yes the posts were related, as I'm trying to plot an HTML 28-day calendar
> with objects coming from a queryset. It's a little bit challenging with
> Python and Django templating, but I'm determined to find a good solution
> without resorting to PHP-style mixing of programming logic with
> presentation.
>
> Right now, I can easily create that calendar with dates using a custom tag
> I write, but the trick is to properly associate events coming from my
> model with the dates coming from context in my template tag.
>
> Below is the code I wrote so far (inclusion tag and corresponding calendar
> template):
>
> [file:dashboardcalendar.py]
>
> from datetime import datetime, timedelta
> from django.template import Library,Node
>
> register = Library()
>
>
> def plot_calendar(context):
> """
> Plot milestones into an XHTML calendar
>
> Calendar starts today and ends at the end of day range defined by days
> (default = 28)
> """
>
> week = [datetime.today() + timedelta(days = n) for n in range(7)]
> week_days = [d.strftime("%A") for d in week]
>
> if context.has_key('calendar_milestones'):
> milestones = context['calendar_milestones']
> else:
> milestones = None
>
> if not context.has_key('weeks'):
> days = int(context['weeks']) * 7
> else:
> days = 28
>
> dates = []
>
> for n in range(days):
> date = datetime.today() + timedelta(days=n)
> dates.append(date)
>
> return {
> 'week_days': week_days,
> 'calendar_days': dates,
> 'calendar_milestones': milestones,
> }
>
> register.inclusion_tag('dashboard/widgets/calendar.html',
> takes_context = True)(plot_calendar)
>
>
>
> [file: calendar.html]
> {% if week_days %}
> <!-- BEGIN upcoming milestones claendar -->
> <table summary="Milestones due in the next 4 weeks" cellspacing='1'
> class="calendar">
> <caption>Milestones due in the next 4 weeks</caption>
> <thead>
> <tr>
> {% for w in week_days %}
> <th>{{ w }}</th>
> {% endfor %}
> </tr>
> </thead>
>
> <tbody>
> {% if calendar_days %}
> {% for d in calendar_days %}
> {% if forloop.counter0|divisibleby:7 %}
> {% if not forloop.first %}</tr>{% endif %}
> {% if not forloop.last %}<tr>{% endif %}
> {% endif %}
> {% if forloop.first %}
> <td class="today">
> <ul><li><strong>TODAY</strong>
> <!-- if there are milestones due today, show them here
> -->
>
> {% else %}
> <td>
> <ul><li>{{ d|date:"j N" }}
> {% endif %}
> !-- if there are milestones due today, show them here
> -->
>
> </li></ul>
> </td>
> {% endfor %}
> {% else %}
> <tr>
> <td colspan="7">
> <div class="error">Can't create calendar cells because
> I don't know
> the date range</div>
> </td>
> </tr>
> {% endif %}
> </tbody>
> </table>
> <!-- END upcoming milestones calendar --> {% endif %}
>
> <!-- just testing -->
> {% if calendar_milestones %}
> <ul>
> {% for m in calendar_milestones %}
> <li>{{ m.date_close|date:"j F" }} | {{ m.name }} ({{
> m.project.name }})</li>
> {% endfor %}
> </ul>
> {% endif %}
>
>
>
I created "customfilters.py":
from django.template import Library
register = Library()
@register.filter("isSunday")
def isSunday(var):
if var.weekday() == 6:
return True
return False
then in my template
{% load customfilters %}
...
{% if d|isSunday %}<td class="sunday">{% else %}<td>{% endif %}
...
and it worked. Now I need to add checks for a datetime object to
'isSunday' in my custom filter.
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