Add minimal to_char for date and datetime on SQLite

We support only date and datetime with common pattern between SQL and Python.

issue8464
review261761002

CHANGELOG

@@ -1,3 +1,4 @@
+* Add partial TO_CHAR support for date and datetime on SQLite
 * Setup default logging for WSGI app
 * Add format argument to report format_date function
 * Change expand attribute into a factor

trytond/backend/sqlite/database.py

@@ -140,6 +140,50 @@ def now():
 _nows = WeakKeyDictionary()
 
 
+def to_char(value, format):
+    try:
+        value = datetime.datetime.strptime(value, '%Y-%m-%d %H:%M:%S.%f')
+    except ValueError:
+        try:
+            value = datetime.datetime.strptime(value, '%Y-%m-%d').date()
+        except ValueError:
+            pass
+    if isinstance(value, datetime.date):
+        # Convert SQL pattern into compatible Python
+        return value.strftime(format
+            .replace('%', '%%')
+            .replace('HH12', '%I')
+            .replace('HH24', '%H')
+            .replace('HH', '%I')
+            .replace('MI', '%M')
+            .replace('SS', '%S')
+            .replace('US', '%f')
+            .replace('AM', '%p')
+            .replace('A.M.', '%p')
+            .replace('PM', '%p')
+            .replace('P.M.', '%p')
+            .replace('am', '%p')
+            .replace('a.m.', '%p')
+            .replace('pm', '%p')
+            .replace('p.m.', '%p')
+            .replace('YYYY', '%Y')
+            .replace('YY', '%y')
+            .replace('Month', '%B')
+            .replace('Mon', '%b')
+            .replace('MM', '%m')
+            .replace('Day', '%A')
+            .replace('Dy', '%a')
+            .replace('DDD', '%j')
+            .replace('DD', '%d')
+            .replace('D', '%w')
+            .replace('TZ', '%Z')
+            )
+    elif isinstance(value, datetime.timedelta):
+        raise NotImplementedError
+    else:
+        raise NotImplementedError
+
+
 class SQLiteSubstring(Function):
     __slots__ = ()
     _function = 'SUBSTR'
@@ -290,6 +334,7 @@ class Database(DatabaseInterface):
         self._conn.create_function('date_trunc', 2, date_trunc)
         self._conn.create_function('split_part', 3, split_part)
         self._conn.create_function('position', 2, SQLitePosition.position)
+        self._conn.create_function('to_char', 2, to_char)
         self._conn.create_function('overlay', 3, SQLiteOverlay.overlay)
         self._conn.create_function('overlay', 4, SQLiteOverlay.overlay)
         if sqlite.sqlite_version_info < (3, 3, 14):

trytond/tests/test_backend.py

@@ -1,9 +1,10 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
+import datetime
 import unittest
 
 from sql import Select
-from sql.functions import CurrentTimestamp
+from sql.functions import CurrentTimestamp, ToChar
 
 from trytond.tests.test_tryton import activate_module, with_transaction
 from trytond.transaction import Transaction
@@ -59,6 +60,30 @@ class BackendTestCase(unittest.TestCase):
 
         self.assertNotEqual(current, second)
 
+    @with_transaction()
+    def test_to_char_datetime(self):
+        "Test TO_CHAR with datetime"
+        now = datetime.datetime.now()
+        query = Select([ToChar(now, 'YYYYMMDD HH24:MI:SS.US')])
+        cursor = Transaction().connection.cursor()
+
+        cursor.execute(*query)
+        text, = cursor.fetchone()
+
+        self.assertEqual(text, now.strftime('%Y%m%d %H:%M:%S.%f'))
+
+    @with_transaction()
+    def test_to_char_date(self):
+        "Test TO_CHAR with date"
+        today = datetime.date.today()
+        query = Select([ToChar(today, 'YYYY-MM-DD')])
+        cursor = Transaction().connection.cursor()
+
+        cursor.execute(*query)
+        text, = cursor.fetchone()
+
+        self.assertEqual(text, today.strftime('%Y-%m-%d'))
+
 
 def suite():
     return unittest.TestLoader().loadTestsFromTestCase(BackendTestCase)