Fixed #27828 -- Fixed a crash when subtracting Integer/DurationField from DateField on Oracle/PostgreSQL.

django/db/models/expressions.py

@@ -383,7 +383,7 @@ class CombinedExpression(Expression):
             return DurationExpression(self.lhs, self.connector, self.rhs).as_sql(compiler, connection)
         if (lhs_output and rhs_output and self.connector == self.SUB and
             lhs_output.get_internal_type() in {'DateField', 'DateTimeField', 'TimeField'} and
-                lhs_output.get_internal_type() == lhs_output.get_internal_type()):
+                lhs_output.get_internal_type() == rhs_output.get_internal_type()):
             return TemporalSubtraction(self.lhs, self.rhs).as_sql(compiler, connection)
         expressions = []
         expression_params = []

docs/releases/1.10.6.txt

@@ -14,3 +14,6 @@ Bugfixes
 
 * Fixed ``RequestDataTooBig`` and ``TooManyFieldsSent`` exceptions crashing
   rather than generating a bad request response (:ticket:`27820`).
+
+* Fixed a crash on Oracle and PostgreSQL when subtracting ``DurationField``
+  or ``IntegerField`` from ``DateField`` (:ticket:`27828`).

tests/expressions/tests.py

@@ -1184,6 +1184,12 @@ class FTimeDeltaTests(TestCase):
         ).order_by('name')
         self.assertQuerysetEqual(over_estimate, ['e3', 'e4'], lambda e: e.name)
 
+    def test_date_minus_duration(self):
+        more_than_4_days = Experiment.objects.filter(
+            assigned__lt=F('completed') - Value(datetime.timedelta(days=4), output_field=models.DurationField())
+        )
+        self.assertQuerysetEqual(more_than_4_days, ['e3', 'e4'], lambda e: e.name)
+
     def test_negative_timedelta_update(self):
         # subtract 30 seconds, 30 minutes, 2 hours and 2 days
         experiments = Experiment.objects.filter(name='e0').annotate(