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172

answers:

1

I've tried adding the following line to my handler script (main.py), but it doesn't seem to work:

sys.path.append('subdir')

subdir lives in the my root directory (i.e. the one containing app.yaml).

This doesn't seem to work, because when I try to import modules that live in subdir, my app explodes.

+4  A: 

1) Ensure you have a blank __init__.py file in subdir.

2) Use a full path; something like this:

import os
import sys

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

Edit: providing more info to answer questions asked in a comment.

As Nick Johnson demonstrates you can place those three lines of code in a file called fix_path.py. Then, in your main.py file, do this import fix_path before all other imports. Link to a tested application using this technique.

And, yes, the __init__.py file is required; per the documentation:

When importing the package, Python searches through the directories on sys.path looking for the package subdirectory.

The __init__.py files are required to make Python treat the directories as containing packages; this is done to prevent directories with a common name, such as string, from unintentionally hiding valid modules that occur later on the module search path. In the simplest case, __init__.py can just be an empty file, but it can also execute initialization code for the package or set the __all__ variable, described later.

Adam Bernier
I don't want to create a package named subdir. Isn't that what 1) will do? Also, where would I put the code you mentioned under 2)??
allyourcode
@allyourcode: see edited answer.
Adam Bernier
2) is the answer I'm looking for. 1) As your quote from the docs explains, this makes subdir a package, which is NOT what I want.
allyourcode
Actually, I'm not sure why my original method of adding sys.path.append('subdir') to main.py (the only non-static handler in my app.yaml) didn't work. I just tried it again, but this time, no explosion :/
allyourcode
The `__init__.py` is **not** required when altering `sys.path`. The path you are adding isn't a module itself, rather its contents are.
Bob Aman
Thanks, Bob. You make a couple of good points.
Adam Bernier