Fixed #24699 -- Added aggregate support for DurationField on Oracle

django/db/backends/base/features.py

@@ -157,9 +157,6 @@ class BaseDatabaseFeatures(object):
     # Support for the DISTINCT ON clause
     can_distinct_on_fields = False
 
-    # Can the backend use an Avg aggregate on DurationField?
-    can_avg_on_durationfield = True
-
     # Does the backend decide to commit before SAVEPOINT statements
     # when autocommit is disabled? http://bugs.python.org/issue8145#msg109965
     autocommits_when_autocommit_is_off = False

django/db/backends/oracle/features.py

@@ -39,7 +39,6 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     uppercases_column_names = True
     # select for update with limit can be achieved on Oracle, but not with the current backend.
     supports_select_for_update_with_limit = False
-    can_avg_on_durationfield = False  # Pending implementation (#24699).
 
     def introspected_boolean_field_type(self, field=None, created_separately=False):
         """

django/db/backends/oracle/functions.py

@@ -0,0 +1,24 @@
+from django.db.models import DecimalField, DurationField, Func
+
+
+class IntervalToSeconds(Func):
+    function = ''
+    template = """
+    EXTRACT(day from %(expressions)s) * 86400 +
+    EXTRACT(hour from %(expressions)s) * 3600 +
+    EXTRACT(minute from %(expressions)s) * 60 +
+    EXTRACT(second from %(expressions)s)
+    """
+
+    def __init__(self, expression, **extra):
+        output_field = extra.pop('output_field', DecimalField())
+        super(IntervalToSeconds, self).__init__(expression, output_field=output_field, **extra)
+
+
+class SecondsToInterval(Func):
+    function = 'NUMTODSINTERVAL'
+    template = "%(function)s(%(expressions)s, 'SECOND')"
+
+    def __init__(self, expression, **extra):
+        output_field = extra.pop('output_field', DurationField())
+        super(SecondsToInterval, self).__init__(expression, output_field=output_field, **extra)

django/db/models/aggregates.py

@@ -78,6 +78,15 @@ class Avg(Aggregate):
         output_field = extra.pop('output_field', FloatField())
         super(Avg, self).__init__(expression, output_field=output_field, **extra)
 
+    def as_oracle(self, compiler, connection):
+        if self.output_field.get_internal_type() == 'DurationField':
+            expression = self.get_source_expressions()[0]
+            from django.db.backends.oracle.functions import IntervalToSeconds, SecondsToInterval
+            return compiler.compile(
+                SecondsToInterval(Avg(IntervalToSeconds(expression)))
+            )
+        return super(Avg, self).as_sql(compiler, connection)
+
 
 class Count(Aggregate):
     function = 'COUNT'
@@ -137,6 +146,15 @@ class Sum(Aggregate):
     function = 'SUM'
     name = 'Sum'
 
+    def as_oracle(self, compiler, connection):
+        if self.output_field.get_internal_type() == 'DurationField':
+            expression = self.get_source_expressions()[0]
+            from django.db.backends.oracle.functions import IntervalToSeconds, SecondsToInterval
+            return compiler.compile(
+                SecondsToInterval(Sum(IntervalToSeconds(expression)))
+            )
+        return super(Sum, self).as_sql(compiler, connection)
+
 
 class Variance(Aggregate):
     name = 'Variance'

tests/aggregation/tests.py

@@ -10,7 +10,7 @@ from django.db.models import (
     F, Aggregate, Avg, Count, DecimalField, DurationField, FloatField, Func,
     IntegerField, Max, Min, Sum, Value,
 )
-from django.test import TestCase, ignore_warnings, skipUnlessDBFeature
+from django.test import TestCase, ignore_warnings
 from django.test.utils import Approximate, CaptureQueriesContext
 from django.utils import six, timezone
 from django.utils.deprecation import RemovedInDjango20Warning
@@ -441,11 +441,16 @@ class AggregateTestCase(TestCase):
         vals = Book.objects.annotate(num_authors=Count("authors__id")).aggregate(Avg("num_authors"))
         self.assertEqual(vals, {"num_authors__avg": Approximate(1.66, places=1)})
 
-    @skipUnlessDBFeature('can_avg_on_durationfield')
     def test_avg_duration_field(self):
         self.assertEqual(
             Publisher.objects.aggregate(Avg('duration', output_field=DurationField())),
-            {'duration__avg': datetime.timedelta(1, 43200)}  # 1.5 days
+            {'duration__avg': datetime.timedelta(days=1, hours=12)}
+        )
+
+    def test_sum_duration_field(self):
+        self.assertEqual(
+            Publisher.objects.aggregate(Sum('duration', output_field=DurationField())),
+            {'duration__sum': datetime.timedelta(days=3)}
         )
 
     def test_sum_distinct_aggregate(self):
@@ -984,17 +989,20 @@ class AggregateTestCase(TestCase):
             Book.objects.annotate(Max('id')).annotate(Sum('id__max'))
 
     def test_add_implementation(self):
-        try:
+        class MySum(Sum):
+            pass
+
         # test completely changing how the output is rendered
         def lower_case_function_override(self, compiler, connection):
             sql, params = compiler.compile(self.source_expressions[0])
             substitutions = dict(function=self.function.lower(), expressions=sql)
             substitutions.update(self.extra)
             return self.template % substitutions, params
-            setattr(Sum, 'as_' + connection.vendor, lower_case_function_override)
+        setattr(MySum, 'as_' + connection.vendor, lower_case_function_override)
 
-            qs = Book.objects.annotate(sums=Sum(F('rating') + F('pages') + F('price'),
+        qs = Book.objects.annotate(
-                                       output_field=IntegerField()))
+            sums=MySum(F('rating') + F('pages') + F('price'), output_field=IntegerField())
+        )
         self.assertEqual(str(qs.query).count('sum('), 1)
         b1 = qs.get(pk=self.b4.pk)
         self.assertEqual(b1.sums, 383)
@@ -1002,11 +1010,12 @@ class AggregateTestCase(TestCase):
         # test changing the dict and delegating
         def lower_case_function_super(self, compiler, connection):
             self.extra['function'] = self.function.lower()
-                return super(Sum, self).as_sql(compiler, connection)
+            return super(MySum, self).as_sql(compiler, connection)
-            setattr(Sum, 'as_' + connection.vendor, lower_case_function_super)
+        setattr(MySum, 'as_' + connection.vendor, lower_case_function_super)
 
-            qs = Book.objects.annotate(sums=Sum(F('rating') + F('pages') + F('price'),
+        qs = Book.objects.annotate(
-                                       output_field=IntegerField()))
+            sums=MySum(F('rating') + F('pages') + F('price'), output_field=IntegerField())
+        )
         self.assertEqual(str(qs.query).count('sum('), 1)
         b1 = qs.get(pk=self.b4.pk)
         self.assertEqual(b1.sums, 383)
@@ -1016,15 +1025,14 @@ class AggregateTestCase(TestCase):
             substitutions = dict(function='MAX', expressions='2')
             substitutions.update(self.extra)
             return self.template % substitutions, ()
-            setattr(Sum, 'as_' + connection.vendor, be_evil)
+        setattr(MySum, 'as_' + connection.vendor, be_evil)
 
-            qs = Book.objects.annotate(sums=Sum(F('rating') + F('pages') + F('price'),
+        qs = Book.objects.annotate(
-                                       output_field=IntegerField()))
+            sums=MySum(F('rating') + F('pages') + F('price'), output_field=IntegerField())
+        )
         self.assertEqual(str(qs.query).count('MAX('), 1)
         b1 = qs.get(pk=self.b4.pk)
         self.assertEqual(b1.sums, 2)
-        finally:
-            delattr(Sum, 'as_' + connection.vendor)
 
     def test_complex_values_aggregation(self):
         max_rating = Book.objects.values('rating').aggregate(