Random test cases

xx.py

#import settings
import dev_settings as settings
from django.core.management import setup_environ
setup_environ(settings)

from django.db.models import Max

from eos.listings.models import Residential

from random import randint

COUNT = 5
#FILTER = {'imagegallery__isnull': False, 'website_display': True}
FILTER = {'website_display': True}
EXCLUDE = {'status__in': ['Archived', 'Pending']}


def case1():
    """
    DB case.
    """
    pks = [k['id'] for k in
        Residential.objects.filter(**FILTER).exclude(**EXCLUDE).values(
            'id').order_by('?')[:COUNT]]
    objs = Residential.objects.filter(pk__in=pks, **FILTER).exclude(**EXCLUDE)

    # Force lazily-evaluated queries to execute
    len([i for i in objs])


def yield_number_of_random_items(model, maximum_objects, filter_keywords={},
        exclude_keywords={}, absolute_max=1000):
    """
    give me a model and a number of items you want to randomly select and
    I will yield those to you. This is far more efficient than forwarding
    the random selection to the db by order_by('?').
    Any keywords that you would like to/ or not be in the yielded results,
    please specfy in filter_keywords, exclude_keywords.
    """
    max_ = model.objects.aggregate(Max('id'))['id__max']
    i = 0
    j = 0
    used_ids = []
    while i < maximum_objects and j < absolute_max:
        pk = randint(1, max_)
        if pk not in used_ids:
            used_ids.append(pk)
            filter_keywords['pk'] = pk
            item = model.objects.filter(**filter_keywords).exclude(
                **exclude_keywords)
            if item:
                yield item[0]
                i += 1
        j += 1


def case2():
    """
    Python case.
    """
    objs = yield_number_of_random_items(Residential, COUNT, FILTER, EXCLUDE)

    # Force lazily-evaluated queries to execute
    len([i for i in objs])