Sort and limit the set of queries by the number of comments and date using queryset.extra () (django)

Question

I am trying to sort / narrow the set of requests for objects based on the number of comments that each object has, as well as the timeframe during which the comments were sent. I use a method queryset.extra()(using django_commentsone that uses shared foreign keys).

I got the idea to use queryset.extra()(and code) here . This is the next question from my initial question yesterday (which shows that I'm moving forward).

Current code:

What I still work is that it will sort by the number of comments; however, I want to expand the functionality, and also be able to pass the argument of the time interval (for example, 7 days) and return an ordered list of the most comments in this time frame.

Here's what my view looks like with 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 tried:

I am not good at SQL, but I tried just adding one more criterion WHEREto find out if I can 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 it did nothing but mess with my sort order.

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

Thanks for any help or insight.

Answer 1

[, (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')

cutoff_date, awesome-in-a-box relativedelta python-dateutil module:

from datetime import relativedelta
from datetime import date

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