import json fails between GAE dev 1.7.0 and 1.7.7

Question

Just updated GAE Python dev environment from 1.7.0 to 1.7.7, and hit an error:

ImportError: No module named json

So I created a minimum test case, here's the app.yap:

application: myapp

version: 1
api_version: 1
runtime: python27
threadsafe: true  

libraries:
- name: jinja2
  version: "2.6"

handlers:
- url: /test.*
  script: test.app
  login: required

- url: /.*
  script: routes.app
  login: required

and the test.py:

import webapp2
import json

class MainHandler(webapp2.RequestHandler):

    def get(self):
        self.response.out.write("test.py")

app = webapp2.WSGIApplication([('/test', MainHandler)],
    debug=True)

Switching dev environments is perfectly consistent - the error is thrown on 1.7.7 but not 1.7.0 (running dev environment from terminal on Linux). I've not tried uploading this to a production environment. It occurred while attempting to upgrade from Python 2.5 to 2.7, so may be due to my unfamiliarity with 2.7.

are you running the python 2.7 interpreter and runtime? sounds like your python install might be missing the json library. — dragonx, Apr 22 '13 at 16:47
Yep, python -V gives Python 2.7.3. Also, it runs fine when I downgrade the dev environment to 1.7.0 from the latest (1.7.7). — cbootle, Apr 23 '13 at 09:02

score 2 · Accepted Answer · answered Apr 23 '13 at 12:34

It was a noobie mistake. As mentioned, I was upgrading from 2.5 to 2.7, during which I moved from importing simplejson to json.

During 2.5 development, I had created a file called json.py, which of course caused a conflict when upgrading to 2.7 and trying to import json, so I renamed that file. Sorry guys, I should have mentioned that, but if I had done so, I would have realized... the json.pyc was still hanging around!

Removing the json.pyc file fixed it. However, it doesn't explain why the presence of json.pyc affected 1.7.7 but not 1.7.0 - switching between the two was perfectly repeatable.

score 0 · Answer 2 · edited May 23 '17 at 11:43

0

You can check for simplejson, as in this post, except I think in GAE you get simplejson from django.utils:

try: from django.utils import simplejson as json
except ImportError: import json

But the Python 2.7 runtime should allow for import json. If the above worked, you were probably running on 2.5.

edited May 23 '17 at 11:43

Community

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answered Apr 22 '13 at 16:37

MichaelJCox

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Yep, had tried that (without try block), and get ImportError: No module named django.utils – cbootle Apr 22 '13 at 16:47
Yes, the dev environment, dev_appserver, under Linux (Ubuntu 12.04) with Python 2.7. – cbootle Apr 22 '13 at 20:31
You can't get a ImportError: No module named django.utils if you are import json with `import json` and you are running python2.7 and an out of the box 1.7.7 SDK. – Tim Hoffman Apr 23 '13 at 10:19

import json fails between GAE dev 1.7.0 and 1.7.7

2 Answers2