从相对路径导入模块

Question

I'm looking for some advice on a python issue I am having. I am a novice at python. I believe that I am relying on my programming experience from other languages to make this work and I have finally come to a stand-still. Here is the scenario, I am importing a module that relies on another module.

My driver for the program, called test.py, starts out like this:

import sys
sys.path.append(r'C:\Program Files (x86)\Zorba XQuery Processor 2.9.1\share\zorba\uris\com\nuemeta\www\modules\DDEXpedite\bindings\Python\Code and Other Files')

import QueryDDEX

Then in the QueryDDEX.py file I have:

import sys,os

temp = os.getcwd()
os.chdir(os.path.dirname(os.path.realpath(__file__)))
sys.path.append(os.path.realpath("..\..\..\..\..\..\..\..\..\python"))

print sys.path

import zorba_api

os.chdir(temp)

In my head I was thinking (1)Save the current working directory, (2)Change the current working directory to the directory of the QueryDDEX.py module, (3) import the zorba_api module from a relative path because if I deploy this module to other computers they may not have the same file structure as mine, and (4) change the current working directory back to what it was initially.

Now, I have read that it is not okay to use relative paths and I have also read that it is okay. I do not see another choice because I did not write the zorba_api so I do not have too much control over it. Anyway, the output of the program is this:

['C:\\Users\\Administrator\\Desktop', 'C:\\Python27\\Lib\\idlelib', 'C:\\Windows\\SYSTEM32\\python27.zip', 'C:\\Python27\\DLLs', 'C:\\Python27\\lib', 'C:\\Python27\\lib\\plat-win', 'C:\\Python27\\lib\\lib-tk', 'C:\\Python27', 'C:\\Python27\\lib\\site-packages', 'C:\\Program Files (x86)\\Zorba XQuery Processor 2.9.1\\share\\zorba\\uris\\com\\nuemeta\\www\\modules\\DDEXpedite\\bindings\\Python\\Code and Other Files', 'C:\\Program Files (x86)\\Zorba XQuery Processor 2.9.1\\share\\zorba\\python']

Traceback (most recent call last):
  File "C:\Users\Administrator\Desktop\Test.py", line 4, in <module>
import QueryDDEX
  File "C:\Program Files (x86)\Zorba XQuery Processor 2.9.1\share\zorba\uris\com\nuemeta\www\modules\DDEXpedite\bindings\Python\Code and Other Files\QueryDDEX.py", line 9, in <module>
    import zorba_api
ImportError: No module named zorba_api

This is where things get tricky in my opinion, the zorba_api module is located at

C:\\Program Files (x86)\\Zorba XQuery Processor 2.9.1\\share\\zorba\\python

and we can see by my debug statement that it IS in the python class path. So why am I getting this error?

Answer 1

Check out this scenario. You have the file alpha.py at C:\\projects\\test\\ . Then you also have a file called beta.py at C:\\projects\\test\\modules\\ so to import beta from alpha you should do:

import modules.beta

Or, not very good but useful, adding the modules directory to your sys.path .

Then if you want to import modules from your beta.py file you will have to take care that you're not at C:\\projects\\test\\modules\\ directory, you're in the alpha.py directory. So for example, if there's a third file called gamma.py at modules/ , if you want to import it from beta.py you should use:

import modules.gamma

Because you are at the importer file ( alpha.py ) path, not at the imported file ( beta.py ) path.

Hope it helps to solve your problem!