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
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

cbootle cbootle · Accepted Answer · 2013-04-23T12:34:03

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.

import json fails between GAE dev 1.7.0 and 1.7.7

2 Answers