I have the following folder structure:
app
__init__.py
utils
__init__.py
transform.py
products
__init__.py
fish.py
In fish.py I'm importing transform as following: import utils.transform.
When I'm running fish.py from Pycharm, it works perfectly fine. However when I am running fish.py from the Terminal, I am getting error ModuleNotFoundError: No module named 'utils'.
Command I use in Terminal: from app folder python products/fish.py.
I've already looked into the solutions suggested here: Importing files from different folder, adding a path to the application folder into the sys.path helps. However I am wondering if there is any other way of making it work without adding two lines of code into the fish.py. It's because I have many scripts in the /products directory, and do not want to add 2 lines of code into each of them.
I looked into some open source projects, and I saw many examples of importing modules from a parallel folder without adding anything into sys.path, e.g. here:
https://github.com/jakubroztocil/httpie/blob/master/httpie/plugins/builtin.py#L5
How to make it work for my project in the same way?
You probably want to run python -m products.fish. The difference between that and python products/fish.py is that the former is roughly equivalent to doing import products.fish in the shell (but with __name__ set to __main__), while the latter does not have awareness of its place in a package hierarchy.
This expands on #Mad Physicist's answer.
First, assuming app is itself a package (since you added __init__.py to it) and utils and products are its subpackages, you should change the import to import app.utils.transform, and run Python from the root directory (the parent of app). The rest of this answer assumes you've done this. (If it wasn't your intention making app the root package, tell me in a comment.)
The problem is that you're running app.products.fish as if it were a script, i.e. by giving the full path of the file to the python command:
python app/products/fish.py
This makes Python think this fish.py file is a standalone script that isn't part of any package. As defined in the docs (see here, under <script>), this means that Python will search for modules in the same directory as the script, i.e. app/products/:
If the script name refers directly to a Python file, the directory
containing that file is added to the start of sys.path, and the file
is executed as the __main__ module.
But of course, the app folder is not in app/products/, so it will throw an error if you try to import app or any subpackage (e.g. app.utils).
The correct way to start a script that is part of a package is to use the -m (module) switch (reference), which takes a module path as an argument and executes that module as a script (but keeping the current working directory as a module search path):
If this option is given, [...] the current directory
will be added to the start of sys.path.
So you should use the following to start your program:
python -m app.products.fish
Now when app.products.fish tries to import the app.utils.transform module, it will search for app in your current working directory (which contains the app/... tree) and succeed.
As a personal recommendation: don't put runnable scripts inside packages. Use packages only to store all the logic and functionality (functions, classes, constants, etc.) and write a separate script to run your application as you wish, putting it outside the package. This will save you from this kind of problems (including the double import trap), and has also the advantage that you can write several run configurations for the same package by just making a separate startup script for each.
Related
I have a python package folder, I am using regularly. As part of my work, I have multiple versions of this package folder.
The folder look something like this,
Main folder
scripts.ipynb
other stuff
package folder
init.py
all submodules folders
The init.py file consists of 'import package_name.submodule_name' lines. I have many main folders, like this one, for all the different versions. If I run the scripts.ipynb notebook, then it works correctly with the wanted package version.
But if I run the notebook, outside of the main_folder, it seems I can not import the package correctly. I want to have the ability to run single scripts notebook, where I can toggle and switch between the different main folders/packages.
Giving unique name for every package is very tedious work, because the name of the package is repeated numerous time along the files. I tried to append the python path to the system, or set the PYTHONPATH to look at the correct folder, but it doesn't help.
In the case of appending the python path to sys, the import routine goes to the correct init.py file, but inside the file it fails to import the submodules. When setting the PYTHONPATH to the folder, no error is given, but the functionality is incorrect (error at first call).
I'm currently trying to import one of my modules from a different folder.
Like this...
from Assets.resources.libs.pout import Printer, ForeColor, BackColor
This import method works completely fine in PyCharm, however, when i try to launch the file in cmd or IDLE, i get this error.
ModuleNotFoundError: No module named 'Assets'
This is my file structure from main.py to pout.py:
- Assets
- main.py
- resources
- libs
- pout.py
Any clue about how i could fix this ?
Any help is appreciated !
Edit: The original answer was based on the assumption that the script you're running is within the folder structure given, which a re-read tells me may not be true. The general solution is to do
sys.path.append('path_to_Assets')
but read below for more detail.
Original answer
The paths that modules can be loaded from will differ between the two methods of running the script.
If you add
import sys
print(sys.path)
to the top of your script before the imports you should be able to see the difference.
When you run it yourself the first entry will be the location of the script itself, followed by various system/environment paths. When you run it in PyCharm you will see the same first entry, followed by an entry for the top level of the project. This is how it finds the modules when run from PyCharm. This behaviour is controlled by the "Add content roots to PYTHONPATH" option in the run configuration.
Adding this path programmatically in a way that will work in all situations isn't trivial because, unlike PyCharm, your script doesn't have a concept of where the top level should be. BUT if you know you'll be running the script from the top level, i.e. your working directory will be the folder containing Assets and you're running something like python Assets/main.py then you can do
sys.path.append(os.path.abspath('.'))
and that will add the correct folder to the path.
Appending sys path didn't work for me on windows, hence here is the solution that worked for me:
Add an empty __init__.py file to each directory
i.e. in Assets, resources, libs.
Then try importing with only the base package names.
Worked for me!
I am in folder2 trying to execute trigger.py
I used:
from ..folder1.subfolder1.function1 import *
from ..folder1.test.py
got error attempted relative import with no known parent package
If you're running out of folder2, then for all practical purposes, trigger.py is a module on its own, not part of a package hierarchy, and can't use relative imports to folder1 (because they're unrelated).
If you can, make your working directory the parent directory of Project, and invoke your script with:
python3 -m Project.folder2.trigger
which runs a module as the main entry point via import syntax, without losing the information on the package structure.
If the whole project is actually installed to system or user site-packages, your working directory won't matter (it's only needed if it's not in sys.path automatically, because the working directory itself is included in sys.path), and the invocation will work anywhere.
I have a few unit tests, which I wrote in Python 2.7. (On PyCharm)
All of these test run locally just fine. However, I am trying to run them on Jenkins automation server.
The problem is that when running on Jenkins I get: "ImportError: Failed to import test module: test_one." I believe this is because an import within that test, which is located a few levels above in the hierarchy. (See hierarchy below)
modules
jira
jira_module #File to be imported
unit_tests
test_one
So, test_one contains the line "import modules.jira.jira_module as jm"
But the command line on Jenkins apparently doesn't like the path using dots. Does anyone know how to solve this issue? I've attempted using runpy - run_path, but that did not work either.
For this line to work
import modules.jira.jira_module as jm
module package modules must be located within PYTHONPATH.
The right approach is that the root directory (which contains modules and unit_tests folders) would the one in which you start the tests. Usually in the project root a bootstrap file is created to run the tests (runtests.py or runtests.sh or similar).
If you don't know how to this, or find this difficult, you could tweak the paths adding the root folder to sys.path in test_one.py. But this is ugly and not right.
I've worked on several medium-sized python applications to date, and every time it seems like I cobble together a terrible system of imports from tangential Stack Overflow answers and half-understood blog posts. It's ugly and hard to maintain and ultimately very unsatisfying. With this question I attempt to put all that behind me.
Say I have a python application split into the following files:
app.py
constants.py
ui/window.py
web/connection.py
With the following include requirements:
app.py needs to include window.py and connection.py
window.py needs to include constants.py and connection.py
connection.py needs to include constants.py
app.py is the starting point for the application, but window.py and connection.py are also invokable from the command line to test basic functionality (ideally from within their respective folders).
What combination of __init__.py files, carefully crafted import statements and wacky python path magic will allow me to achieve this structure?
Thanks very much,
--Dan
It really helps if, instead of thinking in terms of "file structure" first and then trying to figure out the packages, you design things in terms of packages, and then lay out your file structure to implement those packages.
But if you want to know how to hack up what you already have: If you put this at the top level (that is, in one of the paths on your sys.path), and create files names ui/__init__.py and web/__init__.py, then:
app.py can be run as a script.
app.py can be run with -m app.
app.py can be imported with import app.
window.py cannot be run directly.
window.py can be run with -m ui.window.
window.py can be imported with import ui.window.
connection.py cannot be run directly.
connection.py can be run with -m web.connection.
connection.py can be imported with import web.connection.
No wacky path magic is needed; you just need the top level (with app.py, constants.py, ui, and web) to be on your sys.path—which it automatically is when you run with that directory as your working directory, or install everything directly into site-packages, or install it as an egg, etc.
That's as close as you're going to get to what you want. You do ever want to run code with a package directory as your current working directory or otherwise on sys.path, so don't even try. If you think you need that, what you probably want is to separate the runnable code out into a script that you can put at the top level, or somewhere entirely separate. (For example, look at pip or ipython, which installs scripts into somewhere on your system $PATH that do nothing but import some module and run a function.)
The only other thing you might want to consider is putting all of this into a package, say, myapp. You do that by adding a top-level __init__.py, and then running from the parent directory, and adding myapp. to the start of all your importand -m statements. That means you can no longer run app.py as a script either, so again you will need to split the script code out into a separate file from the module that does all the work.
You can use that structure with just a small modification: add empty __init__.py files to the ui/ and web/ directory. Then, where you would have done import window, do either import ui.window, or from ui import window. Similarly, change import connection to import web.connection or from web import connection.
Rationale: Python doesn't work so much with directories as it does with packages, which are directories with an __init__.py in them. By changing ui and web to be packages, you don't have to do any particular Python path magic to work with them, and you get the benefit of adding some structure to your modules and imports. That will become particularly important if you start having modules with the same name in different directories (e.g. a util.py in both the ui and web directories; not necessarily the cleanest design but you get the idea).
If you invoke window.py or connection.py directly to test them, you need to add the top-level directory to your PYTHONPATH for things to still work – but there is a subtle additional wrinkle. When you run this from the top-level directory:
PYTHONPATH=$PWD python web/connection.py
you now have both the top-level directory on your module path AND the web/ directory. This can cause certain relative imports to do unexpected things.
Another way is to use Python's -m option from the top-level directory:
python -m web.foo
I know many folks like to nail their tests right into the modules like this, but I should also note that there are other ways to structure your tests, particularly with an updated unittest library and tools like nosetests, that will make it a little bit easier to run your tests as your project gets larger. See the skeleton here for a reasonable example:
http://learnpythonthehardway.org/book/ex46.html