Django tagging select_related - django

Question

I using Django tagging project.
That is was very stable project.
Working on django 1.3.
But i have a problem.
# in models.py
from tagging.fields import TagField
class Blog(models.Model):
title = models.CharField(max_length = 300)
content = models.TextField()
tags = TagField()
author = models.ForeignKey(User)
# in views.py
def blog_list(request):
# I Want to use select related with tags
blogs = Blog.objects.all().select_related("user", "tags") # ????
....
# in Templates
{% load tagging_tags %}
{% for blog in blogs %}
{% tags_for_object blog as tags %}
{{blog.title}}
{% for tag in tags %}
{{tag}}
{% endfor %}
{% endfor %}

Answer 1

django-tagging uses a generic foreign key to your model, so you can't just use select_related.
Something like this should do the trick though:
from django.contrib.contenttypes.models import ContentType
from collections import defaultdict
from tagging.models import TaggedItem
def populate_tags_for_queryset(queryset):
ctype = ContentType.objects.get_for_model(queryset.model)
tagitems = TaggedItem.objects.filter(
content_type=ctype,
object_id__in=queryset.values_list('pk', flat=True),
)
tagitems = tagitems.select_related('tag')
tags_map = defaultdict(list)
for tagitem in tagitems:
tags_map[tagitem.object_id].append(tagitem.tag)
for obj in queryset:
obj.cached_tags = tags_map[obj.pk]

Answer 2

I have recently encountered the same problem and solved it without a single db query. Indeed, we don't need tag id to get url. As tag name is unique and is db_index you can get url using name field instead of id. E.g.
# your_app/urls.py
url(r'tag/(?P<tag_name>[-\w]+)$', tag_detail_view, name='tag_detail')
Also, tagging TagField gives us a string with tag names, like 'python,django'. So we can write a custom template filter:
# your_app/templatetags/custom_tags.py
from django.urls import reverse
#register.filter
def make_tag_links(tags_str):
return ', '.join([u'%s' % (reverse(
'tag_detail', args=[x]), x) for x in tags_str.split(',')])
And then you can write in template:
# your_list_template.html
{% for blog in blogs %}
{{blog.title}}
{% if blog.tags %}
{{ blog.tags|make_tag_links|safe }}
{% endif %}
{% endfor %}