Fixed #28649 -- Added ExtractIsoYear database function and iso_year lookup.

4 files changed, 12 insertions, 0 deletions

diff --git a/django/db/backends/mysql/operations.py b/django/db/backends/mysql/operations.py
index babf522e45..877c32b6a7 100644
--- a/django/db/backends/mysql/operations.py
+++ b/django/db/backends/mysql/operations.py
@@ -42,6 +42,10 @@ class DatabaseOperations(BaseDatabaseOperations):
             # other database backends.
             # Mode 3: Monday, 1-53, with 4 or more days this year.
             return "WEEK(%s, 3)" % field_name
+        elif lookup_type == 'iso_year':
+            # Get the year part from the YEARWEEK function, which returns a
+            # number as year * 100 + week.
+            return "TRUNCATE(YEARWEEK(%s, 3), -2) / 100" % field_name
         else:
             # EXTRACT returns 1-53 based on ISO-8601 for the week number.
             return "EXTRACT(%s FROM %s)" % (lookup_type.upper(), field_name)
diff --git a/django/db/backends/oracle/operations.py b/django/db/backends/oracle/operations.py
index 62830476bf..7018123cfa 100644
--- a/django/db/backends/oracle/operations.py
+++ b/django/db/backends/oracle/operations.py
@@ -69,6 +69,8 @@ END;
             return "TO_CHAR(%s, 'IW')" % field_name
         elif lookup_type == 'quarter':
             return "TO_CHAR(%s, 'Q')" % field_name
+        elif lookup_type == 'iso_year':
+            return "TO_CHAR(%s, 'IYYY')" % field_name
         else:
             # https://docs.oracle.com/database/121/SQLRF/functions067.htm#SQLRF00639
             return "EXTRACT(%s FROM %s)" % (lookup_type.upper(), field_name)
diff --git a/django/db/backends/postgresql/operations.py b/django/db/backends/postgresql/operations.py
index f4e9571f81..b1b83861c1 100644
--- a/django/db/backends/postgresql/operations.py
+++ b/django/db/backends/postgresql/operations.py
@@ -31,6 +31,8 @@ class DatabaseOperations(BaseDatabaseOperations):
         if lookup_type == 'week_day':
             # For consistency across backends, we return Sunday=1, Saturday=7.
             return "EXTRACT('dow' FROM %s) + 1" % field_name
+        elif lookup_type == 'iso_year':
+            return "EXTRACT('isoyear' FROM %s)" % field_name
         else:
             return "EXTRACT('%s' FROM %s)" % (lookup_type, field_name)
 
diff --git a/django/db/backends/sqlite3/base.py b/django/db/backends/sqlite3/base.py
index 20905c83b8..d124fcd47b 100644
--- a/django/db/backends/sqlite3/base.py
+++ b/django/db/backends/sqlite3/base.py
@@ -338,6 +338,8 @@ def _sqlite_date_extract(lookup_type, dt):
         return dt.isocalendar()[1]
     elif lookup_type == 'quarter':
         return math.ceil(dt.month / 3)
+    elif lookup_type == 'iso_year':
+        return dt.isocalendar()[0]
     else:
         return getattr(dt, lookup_type)
 
@@ -410,6 +412,8 @@ def _sqlite_datetime_extract(lookup_type, dt, tzname):
         return dt.isocalendar()[1]
     elif lookup_type == 'quarter':
         return math.ceil(dt.month / 3)
+    elif lookup_type == 'iso_year':
+        return dt.isocalendar()[0]
     else:
         return getattr(dt, lookup_type)