Django dynamic field name timedelta filter using F()

tasks.py

def filter_urls(urls, hours_ago=None, filter_on='created', all_records=False):
    """Generate queryset from URL model.

    All records or just the ones from the urls parameter
    Restrict the records to those updated before hours_ago or not at all

    Args:
        urls (list): A list of URLs

    Kwargs:
        hours_ago (int): Timedelta in hours (default: None)
        filter_on (str): A field name for the time delta filter (default: 'created')
        all_records (bool): Overrides urls to get all urls (default: False)

    Returns:
        QuerySet object
    """

    # pylint: disable=no-member
    if all_records:
        if hours_ago:  # All URLs with timedelta
            u_insts = URL.objects.annotate(filter_value=F(filter_on)).filter(
                filter_value__lte=timezone.now() - timedelta(hours=hours_ago))
        else:
            u_insts = URL.objects.all()
    elif urls:
        if hours_ago:  # Some URLs with timdelta
            u_insts = URL.objects.annotate(filter_value=F(filter_on)).filter(
                url__in=urls).filter(filter_value__lte=timezone.now() -
                                     timedelta(hours=hours_ago))
        else:  # Some URLs
            u_insts = URL.objects.filter(url__in=urls)
    else:
        raise ValueError("URL Search: Parameters ambiguous")

    return u_insts