Adding a directory to sys.path with pathlib

Question

I'm trying to add a directory to PATH with code like this:

PROJECT_DIR = Path(__file__).parents[2]
sys.path.append(
    PROJECT_DIR / 'apps'
)

It doesn't work. If I do print sys.path I see something like this:

[..., PosixPath('/opt/project/apps')]

How should I fix this code? Is it normal to write str(PROJECT_DIR / 'apps')?

I don't want to avoid this. I just ask what the proper way to use pathlib. — kharandziuk
– kharandziuk, Commented Sep 21, 2015 at 17:40
re. you second question (since it's not covered in answers): yes, it's normal. Documentation mentions str: The string representation of a path is the raw filesystem path itself (in native form, e.g. with backslashes under Windows), which you can pass to any function taking a file path as a string. — vaultah
– vaultah, Commented Sep 21, 2015 at 17:40

hiro protagonist · Accepted Answer · 2023-02-01 10:15:25Z

51

From the docs:

A program is free to modify this list for its own purposes. Only strings should be added to sys.path; all other data types are ignored during import.

Add the path as a string to sys.path:

PROJECT_DIR = Path(__file__).parents[2]
sys.path.append(
    str(PROJECT_DIR / 'apps')
)

PROJECT_DIR is an instance of PosixPath which has all the goodies like / and .parents etc. You need to convert it to a string if you want to append it to sys.path.

edited Feb 1, 2023 at 10:15

answered Sep 21, 2015 at 17:29

hiro protagonist

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2 Comments

florisla Over a year ago

You may want to resolve() the Path before adding it to sys.path. That makes it absolute -- file isnt't always absolute.

hiro protagonist Over a year ago

@florisla as this is done at runtime there is no need for that (as long as you do not move the modules before they are imported).

Tom · Accepted Answer · 2020-11-20 12:52:06Z

9

Support for path-like-objects on sys.path is coming (see this pull request) but not here yet.

answered Nov 20, 2020 at 12:52

Tom

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Comments

Jack Klimov · Accepted Answer · 2020-11-19 06:03:27Z

0

You could also use os.fspath. It return the file system representation of the path.

import os
    
PROJECT_DIR = Path(__file__).parents[2]
APPS_DIR = PROJECT_DIR / 'apps'
sys.path.append(os.fspath(APPS_DIR))

Documentation: https://docs.python.org/3/library/os.html#os.fspath

answered Nov 19, 2020 at 6:03

Jack Klimov

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1 Comment

wim Over a year ago

May as well just use str()

Joran Beasley · Accepted Answer · 2015-09-21 17:39:34Z

-12

project_dir = os.path.join(os.path.abspath(os.path.dirname(__file__)),"..","..")
sys.path.append(os.path.join(project_dir,"apps"))
#or maybe you need it at the start of the path
sys.path.insert(0,os.path.join(project_dir,"apps"))

why are you using this weird pathlib library instead of pythons perfectly good path utils?

edited Sep 21, 2015 at 17:39

answered Sep 21, 2015 at 17:33

Joran Beasley

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11 Comments

hiro protagonist Over a year ago

may be a matter of taste - pathlib is pretty nice!

vaultah Over a year ago

This does not answer the question.

kharandziuk Over a year ago

I guess you miss this part .parents[2] in your answer

hiro protagonist Over a year ago

@Joran Beasley: by all means leave the answer! os.path is a perfectly fine library indeed! and for python <3 none of the pathlib stuff will work.

hiro protagonist Over a year ago

python love! (and: pathlib is builtin in python >3 and evidently backported to python 2.* [as mentioned by kharandziuk]).

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