How to fix Attempted relative import in non-package even with init py

Question

I m trying to follow PEP 328  with the following directory structure   pkg      init   py   components      core py       init   py   tests      core test py       init   py   In core test py I have the following import statement  from   components core import GameLoopEvents   However  when I run  I get the following error   tests  python core test py  Traceback  most recent call last     File  core test py   line 3  in  lt module gt      from   components core import GameLoopEvents ValueError  Attempted relative import in non-package   Searching around I found  relative path not working even with   init   py  and  Import a module from a relative path  but they didn t help   Is there anything I m missing here

User · Answer

Because your code contains if   name         main     which doesn t be imported as a package  you d better use sys path append   to solve the problem

User · Answer

It depends on how you want to launch your script   If you want to launch your UnitTest from the command line in a classic way  that is   python tests core test py   Then  since in this case  components  and  tests  are siblings folders  you can import the relative module either using the insert or the append method of the sys path module  Something like   import sys from os import path sys path append  path dirname  path dirname  path abspath   file          from components core import GameLoopEvents   Otherwise  you can launch your script with the  -m  argument  note that in this case  we are talking about a package  and thus you must not give the   py  extension   that is   python -m pkg tests core test   In such a case  you can simply use the relative import as you were doing   from   components core import GameLoopEvents   You can finally mix the two approaches  so that your script will work no matter how it is called  For example   if   name         main         if   package   is None          import sys         from os import path         sys path append  path dirname  path dirname  path abspath   file                  from components core import GameLoopEvents     else          from   components core import GameLoopEvents

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As Paolo said  we have 2 invocation methods   1  python -m tests core test 2  python tests core test py   One difference between them is sys path 0  string  Since the interpret will search sys path when doing import  we can do with tests core test py   if   name         main         import sys     from pathlib import Path     sys path insert 0  str Path   file    resolve   parent parent       from components import core      lt other stuff gt    And more after this  we can run core test py with other methods   cd tests python core test py python -m core test       Note  py36 tested only

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For me only this worked  I had to explicitly set the value of package to the parent directory  and add the parent directory to sys path from os import path import sys if   package   is None      sys path append  path dirname  path dirname  path abspath   file                package     quot myparent quot   from  subdir import something   the   can now be resolved  I can now directly run my script with python myscript py

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python  lt main module gt  py does not work with relative import The problem is relative import does not work when you run a   main   module from the command line python  lt main module gt  py  It is clearly stated in PEP 338   The release of 2 5b1 showed a surprising  although obvious in retrospect  interaction between this PEP and PEP 328 - explicit relative imports don t work from a main module  This is due to the fact that relative imports rely on   name   to determine the current module s position in the package hierarchy  In a main module  the value of   name   is always    main     so explicit relative imports will always fail  as they only work for a module inside a package    Cause  Python Bug Tracker Issue1510172  Absolute relative import not working    The issue isn t actually unique to the -m switch  The problem is that relative imports are based on   name    and in the main module    name   always has the value   main    Hence  relative imports currently can t work properly from the main module of an application  because the main module doesn t know where it really fits in the Python module namespace  this is at least fixable in theory for the main modules executed through the -m switch  but directly executed files and the interactive interpreter are completely out of luck    To understand further  see Relative imports in Python 3 for the detailed explanation and how to get it over

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If someone is looking for a workaround  I stumbled upon one   Here s a bit of context   I wanted to test out one of the methods I ve in a file   When I run it from within   if   name         main       it always complained of the relative imports   I tried to apply the above solutions  but failed to work  since there were many nested files  each with multiple imports   Here s what I did   I just created a launcher  an external program that would import necessary methods and call them   Though  not a great solution  it works

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This is very confusing  and if you are using IDE like pycharm  it s little more confusing  What worked for me  1  Make pycharm project settings  if you are running python from a VE or from python directory  2  There is no wrong the way you defined  sometime it works with      from folder1 file1 import class  if it does not work  use      import folder1 file1 3  Your environment variable should be correctly mentioned in system or provide it in your command line argument

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To elaborate on Ignacio Vazquez-Abrams s answer   The Python import mechanism works relative to the   name   of the current file   When you execute a file directly  it doesn t have its usual name  but has    main    as its name instead   So relative imports don t work   You can  as Igancio suggested  execute it using the -m option   If you have a part of your package that is meant to be run as a script  you can also use the   package   attribute to tell that file what name it s supposed to have in the package hierarchy    See http   www python org dev peps pep-0366  for details

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As you have already marked everything as a module  there s no need to use the relative reference if you launch as python module   Instead of  from   components core import GameLoopEvents   simply  from pkg components core import GameLoopEvents   When you run from the parent of pkg  use the following  python -m pkg tests core test

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You can use from pkg components core import GameLoopEvents  for example I use pycharm  the below is my project structure image  I just import from the root package  then it works

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My quick-fix is to add the directory to the path   import sys sys path insert 0      components

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Issue is with your testing method   you tried python core test py  then you will get this error ValueError  Attempted relative import in non-package  Reason  you are testing your packaging from non-package source   so test your module from package source   if this is your project structure   pkg      init   py   components      core py       init   py   tests      core test py       init   py   cd pkg  python -m tests core test   dont use  py   or from outside pkg   python -m pkg tests core test   single   if you want to import from folder in same directory   for each step back add one more   hi    hello py how py   in how py  from  hi import hello   incase if you want to import how from hello py  from    import how

User · Answer

Try this  import components from components import

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You can use import components core directly if you append the current directory to sys path   if   name         main    and   package   is None      from os import sys  path     sys path append path dirname path dirname path abspath   file

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Yes  You re not using it as a package   python -m pkg tests core test

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If your use case is for running tests  and it seams that it is  then you can do the following  Instead of running your test script as python core test py use a testing framework such as pytest  Then on the command line you can enter     py test   That will run the tests in your directory  This gets around the issue of   name   being   main   that was pointed out by  BrenBarn  Next  put an empty   init   py file into your test directory  this will make the test directory part of your package  Then you will be able to do  from   components core import GameLoopEvents   However  if you run your test script as a main program then things will fail once again  So just use the test runner  Maybe this also works with other test runners such as nosetests but i haven t checked it  Hope this helps

User · Answer

In core test py  do the following   import sys sys path append     components   from core import GameLoopEvents

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This approach worked for me and is less cluttered than some solutions   try    from   components core import GameLoopEvents except ValueError    from components core import GameLoopEvents   The parent directory is in my PYTHONPATH  and there are   init   py files in the parent directory and this directory   The above always worked in python 2  but python 3 sometimes hit an ImportError or ModuleNotFoundError  the latter is new in python 3 6 and a subclass of ImportError   so the following tweak works for me in both python 2 and 3   try    from   components core import GameLoopEvents except   ValueError  ImportError     from components core import GameLoopEvents

User · Answer

Old thread  I found out that adding an   all      submodule        to the    init   py file and then using the from  lt CURRENT MODULE gt  import   in the target works fine

User · Answer

Here s one way which will piss off everyone but work pretty well  In tests run   ln -s    components components   Then just import components like you normally would

[python] How to fix "Attempted relative import in non-package" even with init.py

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