Question

I’m using python in virtualenv. I have following module:

offers/couchdb.py:

from couchdb.client import Server

def get_attributes():
    return [i for i in Server()['offers']]

if __name__ == "__main__":
    print get_attributes()

When I run it from file I get:

$ python offers/couchdb.py
Traceback (most recent call last):
  File "offers/couchdb.py", line 1, in <module>
    from couchdb.client import Server
  File "/Users/bartekkrupa/D/projects/commercial/echatka/backend/echatka/offers/couchdb.py", line 1,     in <module>
    from couchdb.client import Server
ImportError: No module named client

But when I paste it into interpreter… it works:

$ python
Python 2.7.2 (default, Jun 20 2012, 16:23:33) 
[GCC 4.2.1 Compatible Apple Clang 4.0 (tags/Apple/clang-418.0.60)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from couchdb.client import Server
>>> 
>>> def get_attributes():
...     return [i for i in Server()['offers']]
... 
>>> if __name__ == "__main__":
...     print get_attributes()
... 

What may be the couse that python running that module from file doesn’t load couchdb module, but running in REPL does?

Answer 1

You’ve stumbled across a misfeature: relative imports. When you say from couchdb.client..., Python first looks for a module under offers. that’s named couchdb. And it finds one: the file you’re working on, offers/couchdb.py!

The usual fix is to disable this behavior, which is gone in Python 3 anyway. Put this as the first line of Python code in your file:

from __future__ import absolute_import

Then Python will assume you want to import from a top-level module named couchdb (which you do), not a sibling of the current module.

Unfortunately, in this case, you’re running the file directly, and Python will still add offers/ to its search path. When running a file that’s intended to be a module, you can run it with -m:

python -m offers.couchdb

Now it should work.

(You could, of course, just not name your file couchdb.py. But I find it’s pretty useful to have modules named after the thing they interact with or wrap.)