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

4 files changed, 42 insertions, 4 deletions

diff --git a/django/db/backends/base/features.py b/django/db/backends/base/features.py
index 8c7b31e471..e0a7e49512 100644
--- a/django/db/backends/base/features.py
+++ b/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
diff --git a/django/db/backends/oracle/features.py b/django/db/backends/oracle/features.py
index 2be00acd99..1ef0f232e5 100644
--- a/django/db/backends/oracle/features.py
+++ b/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):
         """
diff --git a/django/db/backends/oracle/functions.py b/django/db/backends/oracle/functions.py
new file mode 100644
index 0000000000..384f092fd4
--- /dev/null
+++ b/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)
diff --git a/django/db/models/aggregates.py b/django/db/models/aggregates.py
index 2d7c43c90e..08c9169c6c 100644
--- a/django/db/models/aggregates.py
+++ b/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'