CODEWITHSUNDEEP
pythonlinuxpackageimporterror
TheOne
TheOne

Reputation: 11159

python packaging causes importerror

I am getting an annoying import error when I try to import a variable in an __init__.py file. I have attached the files involved and my directory structure:

#/home/me/app/app/__init__.py
from flaskext.sqlalchemy import SQLAlchemy

db = SQLAlchemy(app)

#/home/me/app/app/models/__init__.py
from datetime import datetime
from app import db

#shell
[me@archlinux app]$ pwd
/home/me/app
[me@archlinux app]$ ./manage.py 
/home/me/app/app/__init__.pyc
Traceback (most recent call last):
  File "./manage.py", line 7, in <module>
    from app import app
  File "/home/me/app/app/__init__.py", line 3, in <module>
    from app.views.post import post
  File "/home/me/app/app/views/post.py", line 4, in <module>
    from app.models import Post
  File "/home/me/app/app/models/__init__.py", line 5, in <module>
    from app import db
ImportError: cannot import name db

[me@archlinux app]$ tree 
.
├── apikey.txt
├── manage.py
├── app
│   ├── forms
│   │   ├── __init__.py
│   │   └── __init__.py~
│   ├── __init__.py
│   ├── __init__.py~
│   ├── __init__.pyc
│   ├── models
│   │   ├── __init__.py
│   │   ├── __init__.py~
│   │   └── __init__.pyc
│   ├── static
│   │   ├── css
│   │   │   └── style.css
│   │   ├── images
│   │   │   ├── favicon.png
│   │   │   ├── logo.png
│   │   │   ├── text_logo.png
│   │   │   ├── thumb_down_active.png
│   │   │   ├── thumb_down_inactive.png
│   │   │   ├── thumb_up_active.png
│   │   │   └── thumb_up_inactive.png
│   │   ├── js
│   │   │   └── index.js
│   │   └── sitemap.xml
│   ├── templates
│   │   ├── 404.html
│   │   ├── 500.html
│   │   ├── about.html
│   │   ├── base.html
│   │   ├── feedback
│   │   │   └── feedback_form.html
│   │   ├── form.html
│   │   ├── posts
│   │   │   ├── comment.html
│   │   │   ├── post.html
│   │   │   └── posts.html
│   │   ├── spam.html
│   │   ├── terms.html
│   │   └── users
│   │       ├── login_form.html
│   │       └── sign_up_form.html
│   ├── util
│   │   ├── forms.py
│   │   ├── honeypot.py
│   │   ├── __init__.py
│   │   ├── __init__.py~
│   │   ├── json_http.py
│   │   ├── models.py
│   │   └── spam.py
│   └── views
│       ├── feedback.py
│       ├── __init__.py
│       ├── __init__.pyc
│       ├── post.py
│       ├── post.pyc
│       └── user.py
├── settings.py
├── settings.pyc
└── TiddlyWiki.html

13 directories, 49 files

What might be the problem?

Some playing around with pdb_trace() placed right before the import:

(Pdb) import app
(Pdb) app
<module 'app' from '/home/ramin/app/app/__init__.pyc'>
(Pdb) dir(app)
['Flask', '__builtins__', '__doc__', '__file__', '__name__', '__package__', '__path__', 'views']

no db in app :)

Upvotes: 2

Views: 1031

Answers (5)

Gavin Palmer
Gavin Palmer

Reputation: 1220

I was seeing "ImportError: No module named" because my modules didn't have execute permissions.

Upvotes: 0

user199977
user199977

Reputation:

From the stacktrace it seems the following is going on:

  • inside app you import views.post
  • this imports Post from models
  • the models import db from app
  • which will import app, which will import views...

so, looks like a cyclic import?

Upvotes: 0

Adam Vandenberg
Adam Vandenberg

Reputation: 20641

"app/app" is asking for trouble, it both directories are in the search path.

Upvotes: 0

Keith
Keith

Reputation: 43024

This is most often caused by Python finding a package or module with the same name that is different than the one you think it is. I can also happen when you try to run it from withing the package space. First try to change default directory to home, and try again. If it still fails, try adding to the top of your modules:

from __future__ import absolute_import

That prevents the old default behavior of using relative imports from the package space.

Also, in the debugger session, print out the __file__ attribute and check that it is what you expect.

Upvotes: 0

Lennart Regebro
Lennart Regebro

Reputation: 172179

There is likely a problem in the app/__init__.py, that raises an error there, somehow, perhaps a syntax error. These errors have a tendency to be hidden as import errors later.

Put a 

import pdb;pdb.set_trace()

At the beginning of the module that it tries to import. You can then step through that module to see what the real error is.

Upvotes: 4

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