如何解决Google App Engine dev_appserver.py中的Python子模块导入错误？

Hey there, let's break down what's happening and fix this issue with six.moves in your App Engine project.

First, let's recap your setup: You added code in appengine_config.py to import six, print its version (1.11.0) and the six.moves module (which shows as a built-in module), but then hit a runtime error. Here's what's likely going on and how to fix it:

Possible Causes #

The error is probably due to App Engine's sandbox environment handling the built-in six module differently—even though the version looks valid, the six.moves module might be missing some submodules you're trying to use, or the built-in version conflicts with your project's needs.

Fixes to Try #

1. Vendor Your Own Copy of six #

App Engine provides some built-in libraries, but sometimes their versions or configurations don't match project requirements. The best fix here is to bundle your own copy of six with the project:

• Create a requirements.txt file in your project root with this line:

  six==1.11.0
  

• Install the dependency into a lib directory (this is App Engine's standard way to bundle third-party libs):

  pip install -t lib -r requirements.txt
  

• Update your appengine_config.py to load the vendored library first (before importing six):

  from google.appengine.ext import vendor
  # Add the lib directory to the Python path
  vendor.add('lib')
  
  # Now import six
  import six
  print(six.__version__)
  print(six.moves)
  # Your other six.moves usage here
  

This ensures your project uses the exact six version you installed, not the built-in one that's causing issues.

2. Check Specific six.moves Submodule Usage #

If the error happens when you try to import a specific submodule (like six.moves.urllib or six.moves.http_client), double-check:

• That the submodule exists in six 1.11.0 (you can verify this locally by running python -c "import six.moves.xxx" on your machine)
• That App Engine's sandbox allows access to that underlying module. For example, some low-level network modules might have restrictions, so you might need to use App Engine's native alternatives (like google.appengine.api.urlfetch instead of urllib).

3. Get the Full Traceback #

The error snippet you shared is truncated—if you can get the full traceback, it will show exactly which line is failing (e.g., an ImportError for a specific submodule). This will make troubleshooting even more targeted.

内容的提问来源于stack exchange，提问作者EvilTosha