feat: Add support for randomized ordering of fakequeryset (#187)

Fixes #111

CHANGELOG.txt

@@ -4,6 +4,7 @@ Changelog
 6.3 (xx.xx.xxxx)
 ~~~~~~~~~~~~~~~~
 * Support filtering with Q objects (Shohan Dutta Roy)
+* Support random ordering with `.order_by("?")` (Shohan Dutta Roy)
 * Fix: Correctly handle filtering on fields on related models when those fields have names that match a lookup type (Andy Babic)
 * Fix: Correctly handle null foreign keys when traversing related fields (Andy Babic)
 

modelcluster/utils.py

@@ -1,6 +1,7 @@
 from functools import lru_cache
 from django.core.exceptions import FieldDoesNotExist
 from django.db.models import ManyToManyField, ManyToManyRel, Model
+import random
 
 REL_DELIMETER = "__"
 
@@ -154,6 +155,10 @@ def sort_by_fields(items, fields):
     # To get the desired behaviour, we need to order by keys in reverse order
     # See: https://docs.python.org/2/howto/sorting.html#sort-stability-and-complex-sorts
     for key in reversed(fields):
+        if key == '?':
+            random.shuffle(items)
+            continue
+
         # Check if this key has been reversed
         reverse = False
         if key[0] == '-':

tests/tests/test_cluster.py

@@ -780,6 +780,20 @@ def test_ordering_accross_foreignkeys(self):
             )
         )
 
+    def test_random_ordering(self):
+        beatles = Band(name='The Beatles', members=[
+            BandMember(name='John Lennon'),
+            BandMember(name='Paul McCartney'),
+            BandMember(name='George Harrison'),
+            BandMember(name='Ringo Starr'),
+        ])
+
+        # Check that all members are returned
+        self.assertCountEqual(
+            beatles.members.order_by('?'),
+            [beatles.members.get(name=name) for name in ['John Lennon', 'Paul McCartney', 'George Harrison', 'Ringo Starr']]
+        )
+
     def test_filtering_via_manytomany_raises_exception(self):
         bay_window = Feature.objects.create(name="Bay window", desirability=6)
         underfloor_heating = Feature.objects.create(name="Underfloor heading", desirability=10)