How can I add a custom filter to django admin (the filters that appear on the right side of a model dashboard)? I know its easy to include a filter based on a field of that model, but what about a "calculated" field like this:
class NewsItem(models.Model):
headline = models.CharField(max_length=4096, blank=False)
byline_1 = models.CharField(max_length=4096, blank=True)
dateline = models.DateTimeField(help_text=_("date/time that appears on article"))
body_copy = models.TextField(blank=False)
when_to_publish = models.DateTimeField(verbose_name="When to publish", blank=True, null=True)
# HOW CAN I HAVE "is_live" as part of the admin filter? It's a calculated state!!
def is_live(self):
if self.when_to_publish is not None:
if ( self.when_to_publish < datetime.now() ):
return """ <img alt="True" src="/media/img/admin/icon-yes.gif"/> """
else:
return """ <img alt="False" src="/media/img/admin/icon-no.gif"/> """
is_live.allow_tags = True
class NewsItemAdmin(admin.ModelAdmin):
form = NewsItemAdminForm
list_display = ('headline', 'id', 'is_live')
list_filter = ('is_live') # how can i make this work??