allow setting the encoding on QuotedString

psycopg2cffi/_impl/adapters.py

@@ -13,6 +13,8 @@
 
 adapters = {}
 
+DEFAULT_ENCODING = 'latin1'
+
 # Adapters assept python objects and always return bytes, as described in
 # http://initd.org/psycopg/articles/2011/01/24/psycopg2-porting-python-3-report/
 
@@ -224,7 +226,7 @@ def TimestampFromTicks(ticks):
 class QuotedString(_BaseAdapter):
     def __init__(self, obj):
         super(QuotedString, self).__init__(obj)
-        self._default_encoding = "latin1"
+        self._encoding = None
 
     def prepare(self, conn):
         self._conn = conn
@@ -234,7 +236,11 @@ def encoding(self):
         if self._conn:
             return self._conn._py_enc
         else:
-            return self._default_encoding
+            return self._encoding or DEFAULT_ENCODING
+
+    @encoding.setter
+    def encoding(self, value):
+        self._encoding = value
 
     def getquoted(self):
         obj = self._wrapped

psycopg2cffi/tests/psycopg2_tests/test_quote.py

@@ -166,6 +166,9 @@ def test_encoding(self):
         q = psycopg2.extensions.QuotedString('hi')
         self.assertEqual(q.encoding, 'latin1')
 
+        q.encoding = 'ascii'
+        self.assertEqual(q.encoding, 'ascii')
+
         self.conn.set_client_encoding('utf_8')
         q.prepare(self.conn)
         self.assertEqual(q.encoding, 'utf_8')