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

Thanks Mariusz Felisiak for the Oracle workaround.

Backport of d5088f838d from master

django/db/models/expressions.py

@@ -382,7 +382,7 @@ 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

@@ -15,7 +15,7 @@ from django.db.models.expressions import (
     When,
 )
 from django.db.models.functions import (
-    Coalesce, Concat, Length, Lower, Substr, Upper,
+    Cast, Coalesce, Concat, Length, Lower, Substr, Upper,
 )
 from django.test import TestCase, skipIfDBFeature, skipUnlessDBFeature
 from django.test.utils import Approximate
@@ -908,6 +908,15 @@ class FTimeDeltaTests(TestCase):
         ).order_by('name')
         self.assertQuerysetEqual(over_estimate, ['e3', 'e4'], lambda e: e.name)
 
+    def test_date_minus_duration(self):
+        value = (
+            Cast(Value(datetime.timedelta(days=4)), models.DurationField())
+            if connection.vendor == 'oracle'
+            else Value(datetime.timedelta(days=4), output_field=models.DurationField())
+        )
+        more_than_4_days = Experiment.objects.filter(assigned__lt=F('completed') - value)
+        self.assertQuerysetEqual(more_than_4_days, ['e3', 'e4'], lambda e: e.name)
+
 
 class ValueTests(TestCase):
     def test_update_TimeField_using_Value(self):