Mikołaj Torz Mikołaj Torz - 3 months ago 84
Python Question

I get 'ImportError: No module named web' despite the fact that it is installed

I would like to run a simple 'Hello world' app. Every time I run it I get

'ImportError: No module named web'


I installed web.py using pip and using easy_install several times. I tried uninstalling it and installing again. I tried installing it a as sudo. Nothing seems to work. I use OS X

Code of the application:

import web

urls = (
'/', 'index'
)

app = web.application(urls, globals())

class index:
def GET(self):
greeting = "Hello World"
return greeting

if __name__ == "__main__":
app.run()


I tried to run this app using this commend:

python /Users/mptorz/webversion/bin/app.py http://0.0.0.0:8080/


However I know that this is not an issue of the code, because I am basically doing this course http://learnpythonthehardway.org/book/ex50.html.

I thought it might be interesting. I have just tried again to reinstall web.py and I have got this error:

pc7:~ mptorz$ pip uninstall web.py
Uninstalling web.py-0.40.dev0:
/usr/local/lib/python2.7/site-packages/web.py-0.40.dev0-py2.7.egg
Proceed (y/n)? y
Exception:
Traceback (most recent call last):
File "/usr/local/lib/python2.7/site-packages/pip/basecommand.py", line 215, in main
status = self.run(options, args)
File "/usr/local/lib/python2.7/site-packages/pip/commands/uninstall.py", line 76, in run
requirement_set.uninstall(auto_confirm=options.yes)
File "/usr/local/lib/python2.7/site-packages/pip/req/req_set.py", line 336, in uninstall
req.uninstall(auto_confirm=auto_confirm)
File "/usr/local/lib/python2.7/site-packages/pip/req/req_install.py", line 742, in uninstall
paths_to_remove.remove(auto_confirm)
File "/usr/local/lib/python2.7/site-packages/pip/req/req_uninstall.py", line 115, in remove
renames(path, new_path)
File "/usr/local/lib/python2.7/site-packages/pip/utils/__init__.py", line 267, in renames
shutil.move(old, new)
File "/usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 300, in move
rmtree(src)
File "/usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 247, in rmtree
rmtree(fullname, ignore_errors, onerror)
File "/usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 252, in rmtree
onerror(os.remove, fullname, sys.exc_info())
File "/usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 250, in rmtree
os.remove(fullname)
OSError: [Errno 13] Permission denied: '/usr/local/lib/python2.7/site-packages/web.py-0.40.dev0-py2.7.egg/EGG-INFO/dependency_links.txt'


I tried doing the same with sudo and I got this error.

pc7:~ mptorz$ sudo pip uninstall web.py
Password:
The directory '/Users/mptorz/Library/Caches/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
Uninstalling web.py-0.40.dev0:
/usr/local/lib/python2.7/site-packages/web.py-0.40.dev0-py2.7.egg
Proceed (y/n)? y
Successfully uninstalled web.py-0.40.dev0
The directory '/Users/mptorz/Library/Caches/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.


Then I tried to do this:

pc7:~ mptorz$ sudo pip install web.py
The directory '/Users/mptorz/Library/Caches/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
The directory '/Users/mptorz/Library/Caches/pip' or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
Collecting web.py
Downloading web.py-0.38.tar.gz (91kB)
100% |████████████████████████████████| 92kB 199kB/s
Installing collected packages: web.py
Running setup.py install for web.py ... done
Successfully installed web.py-0.38


When I run the app I still get the same error 'ImportError: No module named web'.

I was asked to add the result of python -c "print(import('sys').path)":

pc7:~ mptorz$ python -c "print(__import__('sys').path)"
['', '/Library/Python/2.7/site-packages/pip-8.1.2-py2.7.egg', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python27.zip', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages', '/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-old', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload', '/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/PyObjC', '/Library/Python/2.7/site-packages']


Somone also suggested trying "python -m pip install web.py"
It resulted in this error:

pc7:~ mptorz$ python -m pip install web.py
Collecting web.py
Downloading web.py-0.38.tar.gz (91kB)
100% |████████████████████████████████| 92kB 215kB/s
Installing collected packages: web.py
Running setup.py install for web.py ... error
Complete output from command /usr/bin/python -u -c "import setuptools, tokenize;__file__='/private/var/folders/w6/f08g43wn1zg6ny5b_lq414cr0000gn/T/pip-build-pn7SCD/web.py/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /var/folders/w6/f08g43wn1zg6ny5b_lq414cr0000gn/T/pip-tBblX5-record/install-record.txt --single-version-externally-managed --compile:
running install
running build
running build_py
creating build
creating build/lib
creating build/lib/web
copying web/__init__.py -> build/lib/web
copying web/application.py -> build/lib/web
copying web/browser.py -> build/lib/web
copying web/db.py -> build/lib/web
copying web/debugerror.py -> build/lib/web
copying web/form.py -> build/lib/web
copying web/http.py -> build/lib/web
copying web/httpserver.py -> build/lib/web
copying web/net.py -> build/lib/web
copying web/python23.py -> build/lib/web
copying web/session.py -> build/lib/web
copying web/template.py -> build/lib/web
copying web/test.py -> build/lib/web
copying web/utils.py -> build/lib/web
copying web/webapi.py -> build/lib/web
copying web/webopenid.py -> build/lib/web
copying web/wsgi.py -> build/lib/web
creating build/lib/web/wsgiserver
copying web/wsgiserver/__init__.py -> build/lib/web/wsgiserver
copying web/wsgiserver/ssl_builtin.py -> build/lib/web/wsgiserver
copying web/wsgiserver/ssl_pyopenssl.py -> build/lib/web/wsgiserver
creating build/lib/web/contrib
copying web/contrib/__init__.py -> build/lib/web/contrib
copying web/contrib/template.py -> build/lib/web/contrib
running install_lib
creating /Library/Python/2.7/site-packages/web
error: could not create '/Library/Python/2.7/site-packages/web': Permission denied

----------------------------------------
Command "/usr/bin/python -u -c "import setuptools, tokenize;__file__='/private/var/folders/w6/f08g43wn1zg6ny5b_lq414cr0000gn/T/pip-build-pn7SCD/web.py/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /var/folders/w6/f08g43wn1zg6ny5b_lq414cr0000gn/T/pip-tBblX5-record/install-record.txt --single-version-externally-managed --compile" failed with error code 1 in /private/var/folders/w6/f08g43wn1zg6ny5b_lq414cr0000gn/T/pip-build-pn7SCD/web.py/


After doing everything I was advised here, I tried running the app again and I have got this:

pc7:~ mptorz$ python /Users/mptorz/webversion/bin/app.py http://0.0.0.0:8080/
Traceback (most recent call last):
File "/Users/mptorz/webversion/bin/app.py", line 15, in <module>
app.run()
File "/Library/Python/2.7/site-packages/web/application.py", line 313, in run
return wsgi.runwsgi(self.wsgifunc(*middleware))
File "/Library/Python/2.7/site-packages/web/wsgi.py", line 55, in runwsgi
server_addr = validip(listget(sys.argv, 1, ''))
File "/Library/Python/2.7/site-packages/web/net.py", line 125, in validip
port = int(port)
ValueError: invalid literal for int() with base 10: '//0.0.0.0:8080/'


I have just tried the home-brew solution suggested by @PhilipTzou. After I did that the output of running the app is:

pc7:~ mptorz$ python /Users/mptorz/webversion/bin/app.py http://0.0.0.0:8080/
Traceback (most recent call last):
File "/Users/mptorz/webversion/bin/app.py", line 1, in <module>
import web
File "/usr/local/lib/python2.7/site-packages/web/__init__.py", line 14, in <module>
import utils, db, net, wsgi, http, webapi, httpserver, debugerror
File "/usr/local/lib/python2.7/site-packages/web/wsgi.py", line 8, in <module>
import http
File "/usr/local/lib/python2.7/site-packages/web/http.py", line 16, in <module>
import net, utils, webapi as web
File "/usr/local/lib/python2.7/site-packages/web/webapi.py", line 31, in <module>
import sys, cgi, Cookie, pprint, urlparse, urllib
File "/usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/cgi.py", line 50, in <module>
import mimetools
File "/usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/mimetools.py", line 6, in <module>
import tempfile
File "/usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/tempfile.py", line 32, in <module>
import io as _io
File "/usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/io.py", line 51, in <module>
import _io
ImportError: dlopen(/usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_io.so, 2): Symbol not found: __PyCodecInfo_GetIncrementalDecoder
Referenced from: /usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_io.so
Expected in: flat namespace
in /usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_io.so


SOLUTION
Finally, it worked. After running the solution suggested by @PhilipTzou and entering
python /Users/mptorz/webversion/bin/app.py 8080
app.py is finally working and I can continue my python course. Thank you all for your help :)

Answer

According to the output of your sys.path, you are probably using OSX Python to run your script (app.py) but using Homebrew Python to execute PIP command. The solution is pretty simple:

brew link --overwrite python

This will change your default Python to Homebrew one. After executing this command, you can verify you are using Homebrew Python by typing this command:

which -a python

The result should be like this (sequence matters):

/usr/local/bin/python
/usr/bin/python