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

@@ -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
 ---------------------------
 

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())
 

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())

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__)