From fdfa2de1a1744cabf918d8e4bf2a8740cbba101e Mon Sep 17 00:00:00 2001
From: Daniele Varrazzo <daniele.varrazzo@gmail.com>
Date: Fri, 31 Dec 2010 19:21:44 +0100
Subject: [PATCH] Fixed adaptation of None in composite types (ticket #26).

Added an adapter for None: it is usually not invoked as adaptation to
NULL is a fast path in mogrify, but can be invoked by composite types.
Notice that composite types still have the option to fast-path None
(e.g. list adapter does).
---
 NEWS-2.3              |  7 +++++++
 lib/__init__.py       |  1 +
 lib/extensions.py     | 13 +++++++++++++
 tests/types_extras.py | 20 ++++++++++++++++++++
 4 files changed, 41 insertions(+)

diff --git a/NEWS-2.3 b/NEWS-2.3
index 179ab299..ff211a31 100644
--- a/NEWS-2.3
+++ b/NEWS-2.3
@@ -1,3 +1,10 @@
+What's new in psycopg 2.3.3
+---------------------------
+
+  - Fixed adaptation of None in composite types (ticket #26). Bug report by
+    Karsten Hilbert.
+
+
 What's new in psycopg 2.3.2
 ---------------------------
 
diff --git a/lib/__init__.py b/lib/__init__.py
index 2968284c..065b2a70 100644
--- a/lib/__init__.py
+++ b/lib/__init__.py
@@ -82,6 +82,7 @@ from _psycopg import __version__
 
 import psycopg2.extensions as _ext
 _ext.register_adapter(tuple, _ext.SQL_IN)
+_ext.register_adapter(type(None), _ext.NoneAdapter)
 
 __all__ = filter(lambda k: not k.startswith('_'), locals().keys())
 
diff --git a/lib/extensions.py b/lib/extensions.py
index fca79738..24a9a6b8 100644
--- a/lib/extensions.py
+++ b/lib/extensions.py
@@ -128,4 +128,17 @@ class SQL_IN(object):
     __str__ = getquoted
 
 
+class NoneAdapter(object):
+    """Adapt None to NULL.
+
+    This adapter is not used normally as a fast path in mogrify uses NULL,
+    but it makes easier to adapt composite types.
+    """
+    def __init__(self, obj):
+        pass
+
+    def getquoted(self):
+        return "NULL"
+
+
 __all__ = filter(lambda k: not k.startswith('_'), locals().keys())
diff --git a/tests/types_extras.py b/tests/types_extras.py
index 3986c77f..7f18c96e 100644
--- a/tests/types_extras.py
+++ b/tests/types_extras.py
@@ -364,6 +364,26 @@ class AdaptTypeTestCase(unittest.TestCase):
         d = curs.fetchone()[0]
         self.assertEqual("(42,)", d)
 
+    def test_none_fast_path(self):
+        # the None adapter is not actually invoked in regular adaptation
+        ext = psycopg2.extensions
+
+        class WonkyAdapter(object):
+            def __init__(self, obj): pass
+            def getquoted(self): return "NOPE!"
+
+        curs = self.conn.cursor()
+
+        orig_adapter = ext.adapters[type(None), ext.ISQLQuote]
+        try:
+            ext.register_adapter(type(None), WonkyAdapter)
+            self.assertEqual(ext.adapt(None).getquoted(), "NOPE!")
+
+            s = curs.mogrify("SELECT %s;", (None,))
+            self.assertEqual("SELECT NULL;", s)
+
+        finally:
+            ext.register_adapter(type(None), orig_adapter)
 
 def test_suite():
     return unittest.TestLoader().loadTestsFromName(__name__)