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 %}
        <a href="{% url tag_detail tag_id=tag.pk %}">{{tag}}</a>
    {% 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]