Скачать или смотреть Resolving the ModuleNotFoundError When Importing Python Modules Across Folders

Learn how to fix the `ModuleNotFoundError` in Python when calling scripts from different folders. This guide breaks down the solution and provides clear steps to ensure your imports work correctly.
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This video is based on the question https://stackoverflow.com/q/65837767/ asked by the user 'Liam Wilson' ( https://stackoverflow.com/u/7058439/ ) and on the answer https://stackoverflow.com/a/65837837/ provided by the user 'William Barela' ( https://stackoverflow.com/u/14939733/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding and Fixing Python's ModuleNotFoundError

When working with multiple Python scripts, especially in a hierarchical folder structure, you may encounter the dreaded ModuleNotFoundError. This can be frustrating, particularly when it seems like your imports should be working just fine. Let's take a closer look at a common scenario that could lead to this error and how to resolve it effectively.

The Problem: Importing Across Folder Boundaries

Suppose you have a main script main.py located in a parent directory, and this script interacts with other functions contained within modules found in a subdirectory called child. Here’s a simplified structure to illustrate the situation:

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Your goal might be to call some functions from bar.py in foo.py while executing main.py. However, this setup may throw a ModuleNotFoundError, particularly when you attempt to import bar within foo.py using:

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The Solution: A Step-by-Step Approach

1. Check Import Syntax:

For this scenario, specifically with Python 3.x, the right way to import functions from foo.py in main.py is as follows:

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2. Adding __init__.py for Python 2.7:

If you are using Python 2.7, you must ensure that each child directory includes an __init__.py file. This file can be empty but is necessary for Python to recognize the directory as a package. The required structure would look like this:

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3. Understanding Namespaces:

Make sure you understand that the way Python manages modules and packages means that paths must be explicit. When you import in foo.py, you should access the bar.py module with respect to the package it resides in. Hence, you would adjust the import in foo.py:

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4. Testing Your Setup:

Once you've made these changes, it’s crucial to run your main.py again. Ensure there are no errors. Test it out from the terminal by navigating to the parent directory and executing:

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Conclusion

By following these steps, you can effectively resolve the ModuleNotFoundError that arises when importing Python modules across folders. The key points include ensuring correct import paths, utilizing __init__.py for packages in Python 2.7, and understanding how Python manages namespaces and paths. This knowledge will help streamline your coding process and reduce the chances of encountering similar issues in the future.

Understanding module imports can be tricky, but mastering it will greatly enhance your Python programming skills!