Sort and limit queryset by comment count and date using queryset.extra() (django)

I am trying to sort/narrow a queryset of objects based on the number of comments each object has as well as by the timeframe during which the comments were posted. Am using a queryset.extra() method (using django_comments which utilizes generic foreign keys).

I got the idea for using queryset.extra() (and the code) from here. This is a follow-up question to my initial question yesterday (which shows I am making some progress).

Current Code:

What I have so far works in that it will sort by the number of comments; however, I want to ext开发者_如何学运维end the functionality and also be able to pass a time frame argument (eg, 7 days) and return an ordered list of the most commented posts in that time frame.

Here is what my view looks like with the basic functionality in tact:

import datetime
from django.contrib.comments.models import Comment
from django.contrib.contenttypes.models import ContentType
from django.db.models import Count, Sum
from django.views.generic.list_detail import object_list

def custom_object_list(request, queryset, *args, **kwargs):
    '''Extending the list_detail.object_list to allow some sorting.

    Example: http://example.com/video?sort_by=comments&days=7

    Would get a list of the videos sorted by most comments in the 
    last seven days.
    '''

    try: # this is where I started working on the date business ... 
        days = int(request.GET.get('days', None))
        period = datetime.datetime.utcnow() - datetime.timedelta(days=int(days))
    except (ValueError, TypeError):
        days = None
        period = None

    sort_by = request.GET.get('sort_by', None)
    ctype = ContentType.objects.get_for_model(queryset.model)

    if sort_by == 'comments':
        queryset = queryset.extra(select={
            'count' : """
                SELECT COUNT(*) AS comment_count
                FROM django_comments
                WHERE
                    content_type_id=%s AND
                    object_pk=%s.%s
            """ % ( ctype.pk, queryset.model._meta.db_table, 
                queryset.model._meta.pk.name ),
            },
            order_by=['-count']).order_by('-count', '-created')

    return object_list(request, queryset, *args, **kwargs)

What I've Tried:

I am not well versed in SQL but I did try just to add another WHERE criteria by hand to see if I could make some progress:

    SELECT COUNT(*) AS comment_count
    FROM django_comments
    WHERE
        content_type_id=%s AND
        object_pk=%s.%s AND
        submit_date='2010-05-01 12:00:00'    

But that didn't do anything except mess around with my sort order.

Any ideas on how I can add this extra layer of functionality?

Thanks for any help or insight.

---

Try this [updated to include time difference (cutoff_date) ]

 queryset = queryset.extra(select={
            'comment_count' : """
                SELECT COUNT(*)
                FROM django_comments
                WHERE
                    django_comments.content_type_id=%s AND
                    django_comments.object_pk=%s.%s AND
                    django_comments.submit_date < '%s'
            """ % ( ctype.pk, 
                    queryset.model._meta.db_table, 
                    queryset.model._meta.pk.name,
                    cutoff_date ),
            }).order_by('-comment_count', '-created')

To get a good cutoff_date, I'd recommend using the awesome-in-a-box relativedelta from python-dateutil module:

from datetime import relativedelta
from datetime import date

cutoff_date = date.today() - relativedelta(weeks =1) #relativedelta does all the heavy lifting