Added Json.prepare()

Close #562

NEWS

@@ -21,6 +21,8 @@ What's new in psycopg 2.7.2
 - Fixed `~psycopg2.extras.ReplicationCursor.consume_stream()`
   *keepalive_interval* argument (:ticket:`#547`).
 - Fixed random `!SystemError` upon receiving abort signal (:ticket:`#551`).
+- Added `~psycopg2.extras.Json` `!prepare()` method to consider connection
+  params when adapting (:ticket:`#562`).
 - `~psycopg2.errorcodes` map updated to PostgreSQL 10 beta 1.
 
 

lib/_json.py

@@ -66,6 +66,7 @@ class Json(object):
     """
     def __init__(self, adapted, dumps=None):
         self.adapted = adapted
+        self._conn = None
 
         if dumps is not None:
             self._dumps = dumps
@@ -93,9 +94,15 @@ class Json(object):
                 "json module not available: "
                 "you should provide a dumps function")
 
+    def prepare(self, conn):
+        self._conn = conn
+
     def getquoted(self):
         s = self.dumps(self.adapted)
-        return QuotedString(s).getquoted()
+        qs = QuotedString(s)
+        if self._conn is not None:
+            qs.prepare(self._conn)
+        return qs.getquoted()
 
     if sys.version_info < (3,):
         def __str__(self):

tests/test_types_extras.py

@@ -1084,6 +1084,24 @@ class JsonTestCase(ConnectingTestCase):
         self.assert_(s.startswith("'"))
         self.assert_(s.endswith("'"))
 
+    @skip_if_no_json_module
+    def test_scs(self):
+        cnn_on = self.connect(options="-c standard_conforming_strings=on")
+        cur_on = cnn_on.cursor()
+        self.assertEqual(
+            cur_on.mogrify("%s", [psycopg2.extras.Json({'a': '"'})]),
+            b'\'{"a": "\\""}\'')
+
+        cnn_off = self.connect(options="-c standard_conforming_strings=off")
+        cur_off = cnn_off.cursor()
+        self.assertEqual(
+            cur_off.mogrify("%s", [psycopg2.extras.Json({'a': '"'})]),
+            b'E\'{"a": "\\\\""}\'')
+
+        self.assertEqual(
+            cur_on.mogrify("%s", [psycopg2.extras.Json({'a': '"'})]),
+            b'\'{"a": "\\""}\'')
+
 
 def skip_if_no_jsonb_type(f):
     return skip_before_postgres(9, 4)(f)