flash(my_message) raised 'is not JSON serializable' when Flask 0.9 migrate to 0.10

[adesst]

Fedora 14 64bit, using virtualenv

code in views.py
...
def index()
...
flash(message)
return ...

in Flask 0.9 it works fine.

But when i use 0.10 then it throws me:

Traceback (most recent call last):
File "/opt/flask/lib/python2.7/site-packages/gevent/pywsgi.py", line 438, in handle_one_response
self.run_application()
File "/opt/flask/lib/python2.7/site-packages/gevent/pywsgi.py", line 424, in run_application
self.result = self.application(self.environ, self.start_response)
File "/opt/flask/flask-websocket/app/init.py", line 52, in my_app
return app(environ, start_response)
File "/opt/flask/lib/python2.7/site-packages/flask/app.py", line 1836, in call
return self.wsgi_app(environ, start_response)
File "/opt/flask/lib/python2.7/site-packages/flask/app.py", line 1820, in wsgi_app
response = self.make_response(self.handle_exception(e))
File "/opt/flask/lib/python2.7/site-packages/flask/app.py", line 1403, in handle_exception
reraise(exc_type, exc_value, tb)
File "/opt/flask/lib/python2.7/site-packages/flask/app.py", line 1817, in wsgi_app
response = self.full_dispatch_request()
File "/opt/flask/lib/python2.7/site-packages/flask/app.py", line 1479, in full_dispatch_request
response = self.process_response(response)
File "/opt/flask/lib/python2.7/site-packages/flask/app.py", line 1693, in process_response
self.save_session(ctx.session, response)
File "/opt/flask/lib/python2.7/site-packages/flask/app.py", line 837, in save_session
return self.session_interface.save_session(self, session, response)
File "/opt/flask/lib/python2.7/site-packages/flask/sessions.py", line 326, in save_session
val = self.get_signing_serializer(app).dumps(dict(session))
File "/opt/flask/lib/python2.7/site-packages/itsdangerous.py", line 537, in dumps
payload = want_bytes(self.dump_payload(obj))
File "/opt/flask/lib/python2.7/site-packages/itsdangerous.py", line 809, in dump_payload
json = super(URLSafeSerializerMixin, self).dump_payload(obj)
File "/opt/flask/lib/python2.7/site-packages/itsdangerous.py", line 522, in dump_payload
return want_bytes(self.serializer.dumps(obj))
File "/opt/flask/lib/python2.7/site-packages/flask/sessions.py", line 85, in dumps
return json.dumps(_tag(value), separators=(',', ':'))
File "/opt/flask/lib/python2.7/site-packages/flask/json.py", line 126, in dumps
rv = _json.dumps(obj, **kwargs)
File "/usr/lib64/python2.7/site-packages/simplejson/init.py", line 268, in dumps
use_decimal=use_decimal, **kw).encode(obj)
File "/usr/lib64/python2.7/site-packages/simplejson/encoder.py", line 216, in encode
chunks = list(chunks)
File "/usr/lib64/python2.7/site-packages/simplejson/encoder.py", line 485, in _iterencode
for chunk in _iterencode_dict(o, _current_indent_level):
File "/usr/lib64/python2.7/site-packages/simplejson/encoder.py", line 459, in _iterencode_dict
for chunk in chunks:
File "/usr/lib64/python2.7/site-packages/simplejson/encoder.py", line 380, in _iterencode_list
for chunk in chunks:
File "/usr/lib64/python2.7/site-packages/simplejson/encoder.py", line 459, in _iterencode_dict
for chunk in chunks:
File "/usr/lib64/python2.7/site-packages/simplejson/encoder.py", line 380, in _iterencode_list
for chunk in chunks:
File "/usr/lib64/python2.7/site-packages/simplejson/encoder.py", line 495, in _iterencode
o = _default(o)
File "/opt/flask/lib/python2.7/site-packages/flask/json.py", line 83, in default
return _json.JSONEncoder.default(self, o)
File "/usr/lib64/python2.7/site-packages/simplejson/encoder.py", line 190, in default
raise TypeError(repr(o) + " is not JSON serializable")
TypeError: lu'Transaction 20 of F3535324 has been added ' is not JSON serializable

[mitsuhiko]

Looks like you are flashing a lazy translation object. That is no longer possible because we are no longer using Pickle for security reasons. The solutions is to do flash(unicode(msg)) instead of flash(msg) or use gettext instead of lazy_gettext.

[adesst]

yes, i am using lazy_gettext. Thanks you for the quick response and solution.