Hi
I hope this question isn't too obscure.
I have a base model (not abstract) called BasicPost. I have a model
inheriting from it called PostWithImage. BasicPost has a couple of generic
relations.
In models.py:
class BasicPost(models.Model):
...
authors = generic.GenericRelation(OrderedCredit,
verbose_name=_('authors'),
blank=True, null=True)
...
tags = generic.GenericRelation(TaggedItem, verbose_name=_('tags'),
blank=True, null=True)
...
class PostWithImage(BasicPost):
...
In admin.py:
class TaggedItemInline(generic.GenericTabularInline):
...
model = TaggedItem
...
class OrderedCreditInline(generic.GenericTabularInline):
... # same concept as above
class BasicPostAdmin(admin.ModelAdmin):
inlines = [OrderedCreditInline, TaggedItemInline]
class PostWithImageAdmin(BasicPostAdmin):
...
When I save an object on the PostWithImage admin screen, it sets the
content_type of my generic fields equal to PostWithImage. However if I want
to now retrieve all posts (irrespective of whether they're a BasicPost,
PostWithImage or any other kind of post) with a particular tag, I run into
problems. No simple query will do it, because the tags are pointing to a
bunch of different models. I have found a workaround, but it's ugly and make
expensive database hits. Is there a way I can coerce the admin interface
into saving the tags with content_type pointing to the base class, i.e.
BasicPost?
Thanks.
Regards
Nathan
PS: Here's the ugly workaround. Very difficult for a programmer to decipher
and I suspect it generates very expensive database hits.
class BasicPost(models.Model)
def get_related_posts(self):
tags = self.tags.all()
return BasicPost.objects.filter(
pk__in=
[t.object_id for t in
TaggedItem.objects.filter(tag__name__in=[t.tag.name for
t in tags])
if isinstance(t.content_type.model_class()(),
BasicPost)])\
.select_subclasses().order_by('-date_published')
# Note that I'm using model_utils, hence the select_subclasses method.
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