Added a condition such that querytime filters get added only a single…

… time; extended unittest documentation

versions/models.py

@@ -309,7 +309,7 @@ def get_compiler(self, *args, **kwargs):
         (e.g. by adding a filter to the queryset) does not allow the caching of related
         object to work (they are attached to a queryset; filter() returns a new queryset).
         """
-        if self.querytime.active:
+        if self.querytime.active and (not hasattr(self, '_querytime_filter_added') or not self._querytime_filter_added):
             time = self.querytime.time
             if time is None:
                 self.add_q(Q(version_end_date__isnull=True))
@@ -318,6 +318,9 @@ def get_compiler(self, *args, **kwargs):
                     (Q(version_end_date__gt=time) | Q(version_end_date__isnull=True))
                     & Q(version_start_date__lte=time)
                 )
+            # Ensure applying these filters happens only a single time (even if it doesn't falsify the query, it's
+            # just not very comfortable to read)
+            self._querytime_filter_added = True
         return super(VersionedQuery, self).get_compiler(*args, **kwargs)
 
 
@@ -504,7 +507,6 @@ def get_joining_columns(self, reverse_join=False):
         return joining_columns
 
 
-
 class VersionedManyToManyField(ManyToManyField):
     def __init__(self, *args, **kwargs):
         super(VersionedManyToManyField, self).__init__(*args, **kwargs)

versions_tests/tests/test_models.py

@@ -678,6 +678,10 @@ def setUp(self):
 
         self.t1 = get_utc_now()
         sleep(0.1)
+        # State at t1
+        # Players: [p1.v1, p2.v1]
+        # Teams: [t.v1]
+        # t.player_set = [p1, p2]
 
         team.player_set.remove(p2)
 
@@ -687,6 +691,10 @@ def setUp(self):
 
         self.t2 = get_utc_now()
         sleep(0.1)
+        # State at t2
+        # Players: [p1.v1, p2.v1, p2.v2]
+        # Teams: [t.v1]
+        # t.player_set = [p1]
 
         team.player_set.remove(p1)
 
@@ -696,6 +704,10 @@ def setUp(self):
 
         self.t3 = get_utc_now()
         sleep(0.1)
+        # State at t3
+        # Players: [p1.v1, p2.v1, p2.v2, p1.v2]
+        # Teams: [t.v1]
+        # t.player_set = []
 
         # Let's get those players back into the game!
         team.player_set.add(p1)
@@ -711,10 +723,18 @@ def setUp(self):
 
         self.t4 = get_utc_now()
         sleep(0.1)
+        # State at t4
+        # Players: [p1.v1, p2.v1, p2.v2, p1.v2, p2.v3, p1.v3]
+        # Teams: [t.v1]
+        # t.player_set = [p1, p2]
 
         p1.delete()
 
         self.t5 = get_utc_now()
+        # State at t4
+        # Players: [p1.v1, p2.v1, p2.v2, p1.v2, p2.v3, p1.v3]
+        # Teams: [t.v1]
+        # t.player_set = [p2]
 
     def test_filtering_on_the_other_side_of_the_relation(self):
         self.assertEqual(1, Team.objects.all().count())
@@ -774,6 +794,8 @@ def test_filtering_for_deleted_player_at_t5(self):
     @skipUnless(connection.vendor == 'sqlite', 'SQL is database specific, only sqlite is tested here.')
     def test_query_created_by_filtering_for_deleted_player_at_t5(self):
         team_none_queryset = Team.objects.as_of(self.t5).filter(player__name__startswith='p1')
+        # Validating the current query prior to analyzing the generated SQL
+        self.assertEqual([], list(team_none_queryset))
         team_none_query = str(team_none_queryset.query)
 
         team_table = Team._meta.db_table
@@ -1566,7 +1588,10 @@ def test_select_related(self):
 
     @skipUnless(connection.vendor == 'sqlite', 'SQL is database specific, only sqlite is tested here.')
     def test_select_related_query_sqlite(self):
-        select_related_query = str(Player.objects.as_of(self.t1).select_related('team').all().query)
+        select_related_queryset = Player.objects.as_of(self.t1).select_related('team').all()
+        # Validating the query before verifying the SQL string
+        self.assertEqual(['pl1.v1', 'pl2.v1'], [player.name for player in select_related_queryset])
+        select_related_query = str(select_related_queryset.query)
 
         team_table = Team._meta.db_table
         player_table = Player._meta.db_table
@@ -1625,7 +1650,7 @@ def test_select_related_query_postgresql(self):
                    "{team_table}"."name",
                    "{team_table}"."city_id"
             FROM "{player_table}"
-            LEFT OUTER JOIN "{team_table}" ON ("{player_table}"."team_id" = "{team_table}"."id"
+            LEFT OUTER JOIN "{team_table}" ON ("{player_table}"."team_id" = "{team_table}"."identity"
                                                       AND (({team_table}.version_start_date <= {ts}
                                                             AND ({team_table}.version_end_date > {ts}
                                                                  OR {team_table}.version_end_date IS NULL))))