def fix_data(model_manager, fields_to_update_with_defaults_dict, commit=False):
    bad_ids = []
    all_ids = model_manager.values_list('id', flat=True)
    print "There are {} total IDs.".format(len(all_ids))
    for b_id in all_ids:
        try:
            b = model_manager.get(id=b_id)
        except:
            bad_ids.append(b_id)

    print "There were {0} bad IDs: ".format(len(bad_ids))
    print ", ".join(str(id) for id in bad_ids)

    if commit:
        # fix 'em
        model_manager \
            .filter(id__in=bad_ids) \
            .update(**fields_to_update_with_defaults_dict)
    else:
        print "Didn't fix, just reported."