Importing classes - Python

Question

Good morning I am stuck with the following problem. Precisely, I have the following setup:

Project_Name
|
|--> __init__.py
|
|--> Tool1
|      |
|      |--> Object1.py
|      |
|      |--> __init__.py
|
|--> Tool2
       |
       |--> Object2.py
       |
       |--> __init__.py

where Project_name, Tool1 and Tool2 are folders. Object2 contains a class named 'House'. How can I use the class 'House' in Object1? I tried the following:

from Tool2.Object2 import House

but I receive error message 'No module named 'Tool2'.

What am I doing wrong? All init.py files are empty, should I change that?

Where is the main script being executed? And how do you execute it? From terminal or IDE? — ghchoi, Feb 26 '21 at 14:09
I will use Object1 inside another Project_name-subfolder (namely, the test folder). I use VSCode and its terminal. — Yoda And Friends, Feb 26 '21 at 14:10

Thang Pham · Answer 1 · 2021-02-26T14:53:18.330

You need to export PYTHONPATH to your Project_Name so that the interpreter knows the specific folder(s) to look up.

export PYTHONPATH=path/to/your/project

For example:

object1.py

from tool2.object2 import House

house = House()
house.print_message("Hello World!!!")

object2.py

class House(object):
    def __init__(self):
        pass
    
    def print_message(self, text):
        print(text)

Outputs before and after exporting PYTHONPATH

$ python tool1/object1.py                                                                                                                                                                                                                       
Traceback (most recent call last):
  File "tool1/object1.py", line 2, in <module>
    from tool2.object2 import House
ImportError: No module named tool2.object2

$ pwd                                                                                                                                                                                                                                      
/Users/.../StackOverflow

$ export PYTHONPATH=/Users/.../StackOverflow                                                                                                                                                                

$ python tool1/object1.py                                                                                                                                                                                                                       
Hello World!!!

$ python object1.py                                                                                                                                                                                                                       
Hello World!!!

Can you please be more precise? Where should I place the export statement? — Yoda And Friends, Feb 26 '21 at 14:09
You first need to open the terminal and change directory to your folder `Project_Name`. Next, use the `pwd` commandline to get the path to this folder (let's say X) and replace `path/to/your/project` with X to export. — Thang Pham, Feb 26 '21 at 14:14
Can you show me what do you get from this: `echo $PYTHONPATH` ? — Thang Pham, Feb 26 '21 at 14:18
You should call the script from the `Project_Name` directory like this: `python Tool1/Object1.py` then it should work. — Thang Pham, Feb 26 '21 at 14:28

ghchoi · Accepted Answer · 2021-02-26T15:12:37.797

0

1

If you are using VS code, the easiest fix is to start your script being executed like the following.

import sys

sys.path.append('/PATH/TO/Project_Name')

import Tool1.Object1

...

2

Or, you can add the environment variable PYTHONPATH to settings.json (can be found ctrl + shift + P then type settings.json)

    "terminal.integrated.env.linux": {
        "PYTHONPATH": "/PATH/TO/Project_Name/"
    }

In this way, you can just

import Tool1.Object1

sys.path and PYTHONPATH will do the same for you.

edited Feb 26 '21 at 15:12

answered Feb 26 '21 at 14:17

ghchoi

4,812
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Seem still not working. Now I keep also having the error "unable to import" when I do: from Tool2.Object2 import House. Could it be related to the fact that I set PYTHONPATH=/PATH/TO/Project_Name? – Yoda And Friends Feb 26 '21 at 14:37
I tested. Tell me the command you use to execute your main script. – ghchoi Feb 26 '21 at 14:44
I actually use the function "run in python terminal" of VSCode – Yoda And Friends Feb 26 '21 at 14:52
If you are using VSCode, you might want to check this: https://stackoverflow.com/questions/59702230/how-to-correctly-import-a-python-module-in-vs-code – Thang Pham Feb 26 '21 at 15:04
@YodaAndFriends Edited. Please check. :) – ghchoi Feb 26 '21 at 15:06
Still showing error. But it is working :') – Yoda And Friends Feb 26 '21 at 15:09

Importing classes - Python

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