• Check the logs for the general issues.
• Check the JSON that you’re sending to see if it’s valid. (I had an invalid JSON due to an extra comma)

I was running into several errors while accessing a dictionary persisted in MongoDB as JSON (with Unicode) until I found this post on stackoverflow.com.

TypeError: string indices must be integers, not unicode

So basically the way to workaround the problem is as follows:

import json, ast

# You would assume this would work ...
somekey_val = dict[SOME_KEY]

# but due to frustrations with unicode in python handle it
try:
    somekey_val = ast.literal_eval(dict[SOME_KEY])
except Exception, e:
    print 'unicode conversion not needed for some_key'

# do regular processing from here on
process( somekey_val )

This post from stackoverflow.com explains it.

Basically, you will need to use the default=json_util.default argument as defined in the PyMongo Docs

So, while converting a date object in a dictionary to JSON

from bson import json_util
import json
json_str = json.dumps(anObject, default=json_util.default)
print json_str

And while reading back the JSON string into a dictionary

from bson import json_util
import json
json.loads(json_str, object_hook=json_util.object_hook)

If you’re trying to use the –exec option and need to pass in arguments, then you would need to use — to let –exec know that these are arguments to the script that needs to be executed.

# No arguments passed to test.py
exec start-stop-daemon –start –exec python test.py

# Arguments (-i $PARAM) passed to test.py
exec start-stop-daemon –start –exec python test.py — -i $PARAM

We have a bunch of Python (2.7) virtual environments and I needed a way to figure out a way to list modules installed by pip within the context of that venv and then grep for a particular one. I’m not a super Python expert at this time, but wrote up a small script to list this.

Here’s a python script:

# pip_installed_modules.py 
import pip

def main():
	modules = pip.get_installed_distributions()
	for m in modules:
		print m


if __name__ == "__main__":
    main()

Here’s my alias:

alias pipmodules=’python ~/bin/pip_installed_modules.py’

Now I can simply grep for specific modules or just see the installed modules.