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ValueError: attempted relative import beyond top-level package

I was playing the the Python's import system in order to understand better how it works, and I encountered another problem. I have the following structure

pkg/     __init__.py     c.py     d.py      subpkg/         __init__.py         a.py         b.py 

Inside a.py I have the following code:

from . import b from .. import d 

And inside c.py I have the following:

import subpkg.a 

Now I receive the following error:

ValueError: attempted relative import beyond top-level package

But why? How can I solve it? I am running c.py from the IDLE, and pkg should be considered a package, since it has the __init__.py file.

The first import works fine, but it's the following that doesn't work:

from .. import d 

Because I am attempting to import something from a parent package, but apparently I cannot, for some weird reason.

like image 558
nbro Avatar asked Feb 03 '16 01:02

nbro


People also ask

How do you resolve Valueerror attempted relative import beyond top level package?

The beyond top level package error in relative import error occurs when you use a relative import without the file you are importing being part of a package. To fix this error, make sure that any directories that you import relatively are in their own packages.

How do you use relative import in Python?

Relative imports use dot(.) notation to specify a location. Single dot specifies that the module is in the current directory, two dots indicate that module is in its parent directory of the current location and three dots indicate that it is in grandparent directory and so on.

What is __ init __ PY for?

The __init__.py file makes Python treat directories containing it as modules. Furthermore, this is the first file to be loaded in a module, so you can use it to execute code that you want to run each time a module is loaded, or specify the submodules to be exported.


2 Answers

Python 3 changed the import system so every time you want a module that is around the one you are working, you need relative imports (unless you mess with PYTHONPATH or sys.path).

The correct usage here should be

from .subpkg import a 

When you are working with IDLE, you have a totally different environment. Therefore, you could add the current location to your path so imports work again.

try:

sys.path.insert(0, '') 

It might be weird, but it is for a greater good

PS: If this last thing do not work -- I don't have an IDLE environment right now -- it is probably because the work directory is set wrong.

Try this answer instead: https://stackoverflow.com/a/17361545/754991

like image 20
JBernardo Avatar answered Sep 18 '22 16:09

JBernardo


This had me question my insanity.

The problem stems from the confusion that people mistakenly take the relative import as path relative which is not.

Relative imports depend on the location of the file that is run.

This answer goes deeper into explaining how the python modules actually work, but to summarize.

  1. When a file is loaded, it is given a name:
    • If it was loaded as the top-level script (run directly), its name is __main__.
    • If it was loaded as a module (with import), its name is the filename, preceded by the names of any packages/subpackages of which it is a part, separated by dots - pkg.subpkg.a
  2. If you do a from .. there must be at least 2 dots in the file name. from ... - 3 dots.

Now comes the funny part.

If you run c.py directly, then it is given the name __main__ and a.py has subpkg.a.

As per the 2nd statement, you must have at least 2 dots in the name of subpkg.a to run from .. inside it.

The fix

Create a new file outside the pkg, say main.py

pkg/     __init__.py     c.py     d.py      subpkg/         __init__.py         a.py         b.py main.py 

Inside main.py

import pkg.c 

If we run main.py, it get's the name __main__, and a.py get's pkg.subpkg.a. As per the 2nd statement it now has 2 dots in the name and we can do the from ..

One more thing. Now that c.py is loaded as a module, we have to use from to load a.py.

from .subpkg import a 
like image 128
typhon04 Avatar answered Sep 17 '22 16:09

typhon04