Added support for unicode json dumping. This fixes #535

flask/app.py

@@ -274,7 +274,8 @@ class Flask(_PackageBoundObject):
         'SEND_FILE_MAX_AGE_DEFAULT':            12 * 60 * 60, # 12 hours
         'TRAP_BAD_REQUEST_ERRORS':              False,
         'TRAP_HTTP_EXCEPTIONS':                 False,
-        'PREFERRED_URL_SCHEME':                 'http'
+        'PREFERRED_URL_SCHEME':                 'http',
+        'JSON_AS_ASCII':                        True
     })
 
     #: The rule object to use for URL rules created.  This is used by

flask/json.py

@@ -68,20 +68,37 @@ class JSONDecoder(_json.JSONDecoder):
     """
 
 
+def _dump_arg_defaults(kwargs):
+    """Inject default arguments for dump functions."""
+    if current_app:
+        kwargs.setdefault('cls', current_app.json_encoder)
+        if not current_app.config['JSON_AS_ASCII']:
+            kwargs.setdefault('ensure_ascii', False)
+
+
+def _load_arg_defaults(kwargs):
+    """Inject default arguments for load functions."""
+    if current_app:
+        kwargs.setdefault('cls', current_app.json_decoder)
+
+
 def dumps(obj, **kwargs):
     """Serialize ``obj`` to a JSON formatted ``str`` by using the application's
     configured encoder (:attr:`~flask.Flask.json_encoder`) if there is an
     application on the stack.
+
+    This function can return ``unicode`` strings or ascii-only bytestrings by
+    default which coerce into unicode strings automatically.  That behavior by
+    default is controlled by the ``JSON_AS_ASCII`` configuration variable
+    and can be overriden by the simplejson ``ensure_ascii`` parameter.
     """
-    if current_app:
-        kwargs.setdefault('cls', current_app.json_encoder)
+    _dump_arg_defaults(kwargs)
     return _json.dumps(obj, **kwargs)
 
 
 def dump(obj, fp, **kwargs):
     """Like :func:`dumps` but writes into a file object."""
-    if current_app:
-        kwargs.setdefault('cls', current_app.json_encoder)
+    _dump_arg_defaults(kwargs)
     return _json.dump(obj, fp, **kwargs)
 
 
@@ -90,16 +107,14 @@ def loads(s, **kwargs):
     configured decoder (:attr:`~flask.Flask.json_decoder`) if there is an
     application on the stack.
     """
-    if current_app:
-        kwargs.setdefault('cls', current_app.json_decoder)
+    _load_arg_defaults(kwargs)
     return _json.loads(s, **kwargs)
 
 
 def load(fp, **kwargs):
     """Like :func:`loads` but reads from a file object.
     """
-    if current_app:
-        kwargs.setdefault('cls', current_app.json_decoder)
+    _load_arg_defaults(kwargs)
     return _json.load(fp, **kwargs)
 
 

flask/testsuite/helpers.py

@@ -79,6 +79,19 @@ class JSONTestCase(FlaskTestCase):
             self.assert_equal(rv.mimetype, 'application/json')
             self.assert_equal(flask.json.loads(rv.data), d)
 
+    def test_json_as_unicode(self):
+        app = flask.Flask(__name__)
+
+        app.config['JSON_AS_ASCII'] = True
+        with app.app_context():
+            rv = flask.json.dumps(u'\N{SNOWMAN}')
+            self.assert_equal(rv, '"\\u2603"')
+
+        app.config['JSON_AS_ASCII'] = False
+        with app.app_context():
+            rv = flask.json.dumps(u'\N{SNOWMAN}')
+            self.assert_equal(rv, u'"\u2603"')
+
     def test_json_attr(self):
         app = flask.Flask(__name__)
         @app.route('/add', methods=['POST'])