Python package import from parent directory

问题:

I've the following source code structure

/testapp/
/testapp/__init__.py
/testapp/testmsg.py
/testapp/sub/
/testapp/sub/__init__.py
/testapp/sub/testprinter.py

where testmsg defines the following constant:

MSG = "Test message"

and sub/testprinter.py:

import testmsg

print("The message is: {0}".format(testmsg.MSG))

But I'm getting ImportError: No module named testmsg

Shouldn't it be working since the package structure? I don't really want to extend sys.path in each submodule and I don't even want to use relative import.

What am I doing wrong here?

回答1:

It all depends on which script you run. That script's path will be added to python's search path automatically.

Make it the following structure:

TestApp/
TestApp/README
TestApp/LICENSE
TestApp/setup.py
TestApp/run_test.py
TestApp/testapp/__init__.py
TestApp/testapp/testmsg.py
TestApp/testapp/sub/
TestApp/testapp/sub/__init__.py
TestApp/testapp/sub/testprinter.py

Then run TestApp/run_test.py first:

from testapp.sub.testprinter import functest ; functest()

Then TestApp/testapp/sub/testprinter.py could do:

from testapp.testmsg import MSG
print("The message is: {0}".format(testmsg.MSG))

More good hints here;

回答2:

Use relative import like below

from .. import testmsg

回答3:

This question has the answer - dynamic importing:

How to import a python file in a parent directory

import sys
sys.path.append(path_to_parent)
import parent.file1

Here's something I made to import anything. Of course, you have to still copy this script around to local directories, import it, and use the path you want.

import sys
import os

# a function that can be used to import a python module from anywhere - even parent directories
def use(path):
    scriptDirectory = os.path.dirname(sys.argv[0])  # this is necessary to allow drag and drop (over the script) to work
    importPath = os.path.dirname(path)
    importModule = os.path.basename(path)
    sys.path.append(scriptDirectory+"\\"+importPath)        # Effing mess you have to go through to get python to import from a parent directory

    module = __import__(importModule)
    for attr in dir(module):
        if not attr.startswith('_'):
            __builtins__[attr] = getattr(module, attr)