Importing from a relative path in Python

Question

I have a folder for my client code, a folder for my server code, and a folder for code that is shared between them

Proj/
    Client/
        Client.py
    Server/
        Server.py
    Common/
        __init__.py
        Common.py

How do I import Common.py from Server.py and Client.py?

Answer 1

EDIT Nov 2014 (3 years later):

Python 2.6 and 3.x supports proper relative imports, where you can avoid doing anything hacky. With this method, you know you are getting a relative import rather than an absolute import. The '..' means, go to the directory above me:

from ..Common import Common

As a caveat, this will only work if you run your python as a module, from outside of the package. For example:

python -m Proj

Original hacky way

This method is still commonly used in some situations, where you aren't actually ever 'installing' your package. For example, it's popular with Django users.

You can add Common/ to your sys.path (the list of paths python looks at to import things):

import sys, os
sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'Common'))
import Common

os.path.dirname(__file__) just gives you the directory that your current python file is in, and then we navigate to 'Common/' the directory and import 'Common' the module.

Answer 2

Funny enough, a same problem I just met, and I get this work in following way:

combining with linux command ln , we can make thing a lot simper:

1. cd Proj/Client
2. ln -s ../Common ./

3. cd Proj/Server
4. ln -s ../Common ./

And, now if you want to import some_stuff from file: Proj/Common/Common.py into your file: Proj/Client/Client.py, just like this:

# in Proj/Client/Client.py
from Common.Common import some_stuff

And, the same applies to Proj/Server, Also works for setup.py process, a same question discussed here, hope it helps !

Answer 3

Doing a relative import is absolulutely OK! Here's what little 'ol me does:

#first change the cwd to the script path
scriptPath = os.path.realpath(os.path.dirname(sys.argv[0]))
os.chdir(scriptPath)

#append the relative location you want to import from
sys.path.append("../common")

#import your module stored in '../common'
import common.py