From flask import flask ошибка

Try deleting the virtualenv you created. Then create a new virtualenv with:

virtualenv flask

Then:

cd flask

Now let’s activate the virtualenv

source bin/activate

Now you should see (flask) on the left of the command line.

_{Edit: In windows there is no «source» that’s a linux thing, instead execute the activate.bat file, here I do it using Powershell: PS C:DEVaProject> & .FlaskScriptsactivate)}

Let’s install flask:

pip install flask

Then create a file named hello.py (NOTE: see UPDATE Flask 1.0.2 below):

from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello World!"

if __name__ == "__main__":
    app.run()

and run it with:

python hello.py

UPDATE Flask 1.0.2

With the new flask release there is no need to run the app from your script. hello.py should look like this now:

from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello World!"

and run it with:

FLASK_APP=hello.py flask run

Make sure to be inside the folder where hello.py is when running the latest command.

All the steps before the creation of the hello.py apply for this case as well

Importerror: no module named Flask is among a class of errors that Python shows when it cannot find Flask or a Flask plugin in your Python environment. This article will explain the causes of this error and how you can fix it in your project.

What you’ll learn in this article will allow you to prevent the error now and in the future. Now, switch back to your terminal or IDE, and let’s fix your project/code.

Why Python Shows an Import Error for the Flask Module?

Python shows an import error for the Flask module because of the following:

• Flask is not installed at all
• Flask is not in your Python environment
• Error in the “requirements.txt” file
• Your IDE is using a different Python
• Python cannot access the “site-packages” folder

– Flask Is Not Installed at All

Before you can import Flask or any of its plugins, you must install it because that’s the only way Python can find it before it can import it. This applies irrespective of the environment that you want to use it, including a virtual environment where packages can differ from the base Python installation.

If you don’t install it, that’s when you’ll run into errors like importerror: no module named flask empire error. Plus, you cannot use it on the command line or terminal because it will not exist in the path environment on your computer.

– Flask Is Not in Your Python Environment

When Flask does not exist in your Python environment, there is no way Python can import it. This will happen if you’ve installed multiple versions of Python like “Python 2” and “Python 3+”. So, Flask can exist in “Python 3+” but you’re trying to import it to a project that’s using “Python 2” that does not have Flask. The first scenario that can cause this is if you’re on macOS, and it can lead to the importerror: no module named flask macOS error.

On Mac OSX, it has “Python 2” installed but you can install “Python 3” and your project can be using the default “Python 2”. With this, you can install Flask on “Python 3”, but your project that’s using “Python 2” will not have access to it. As a result, you’ll get an import error when you try to use it because your “Python 2” does not have Flask. The next scenario is if you installed Anaconda and you have “Python 3+” installed.

Anaconda can install “Python 2.7” that can collide with the path of “Python 3” and this can lead to the modulenotfounderror: no module named ‘flask_login’ error. Also, “Raspberry Pi” uses “Python 2” by default but it also has “Python 3”. Now, when you install a Flask plugin like “flask-cors” using “pip install -U flask-cors”, this will work for “Python 2” only and not for “Python 3”.

– Error in the “requirements.txt” File

An error in your “requirements.txt” file will lead to the importerror: no module named flask_restful error. The error is when you spell the Flask Restful plugin as “Flask-RESTful”. This is the official name of the plugin, but it will not work if you spell it that way in the “requirements.txt” file of your project. That’s because imports are case-sensitive as documented in “PEP 8 Style Guide for Python Code” under the section “Package and Module Names”.

– Your Ide Is Using a Different Python

If your Integrated Development Environment (IDE) is using a Python that does not have a Flask module, it will lead to an import error. On VS Code, it will cause the no module named flask vscode error. Other IDEs will report the similar no module named ‘flask’ error if their Python does not have Flask installed.

– Python Cannot Access the “Site-packages” Folder

On a local Python installation, Python stores any package that you download into the “site-packages” folder, this includes the Flask package (or module). Anytime you use the import statement to import Flask into your application, Python will search for it in this folder. If it does not find it there, Python will stop everything and you’ll get an “ImportError” message. This folder can exist but its name was changed or permissions prevented Python from accessing it.

Python will import the Flask module or its plugins if you install Flask or update the “requirements.txt” file in Docker. What’s more, you can also configure your IDE to access the Python installation that has Flask installed. Finally, ensure that the “site-packages” folder exists and Python can access it.

– Install Flask in Your Python Environment

To solve the modulenotfounderror: no module named flask Windows error, you need to install Flask on your Python installation. You can use any of the following to install Flask:

• For “Python 2”: pip install flask
• For “Python 3”: pip3 install flask
• For Linux and “Python 2”: sudo pip install flask
• For Linux and “Python 3”: sudo pip3 install flask
• For Anaconda: conda install -c anaconda flask
• If the pip package is not in your PATH environment variable: python -m pip install flask or python3 -m pip install flask

You can use any of the methods above to install “Flask Cors” and prevent the importerror: no module named ‘flask_cors’ error. But if you’re using a virtual environment, do the following to install Flask:

1. Delete the virtual environment that you created using the “deactivate” command.
2. Create another virtual environment using “virtualenv flask”.
3. Move to this directory using “cd flask”.
4. Activate the environment using “source bin/activate” on Linux.
5. Use “C:directory_of_virtual_envFlaskScriptsactivate” for Windows.
6. Install flask using “pip install flask” or “python -m pip install flask”.

– Update Your “requirements.txt” File

An update to the “requirements.txt” file will fix the importerror: no module named flask Docker error if you’ve included capital letters in the package name. For example, the following “requirements.txt” file has capital letters in the name of the “Flask Restful” plugin.

The following is the correct way to write it:

By using the above version in the “requirements.txt” file you’ll not get an error about “Flask Restful” not being installed when you Dockerize your application. What’s more, you can use “from flask import Flask” and “from flask_restful import <class name>”. Where “<class name>” is a class name from the “flask_restful” module.

– Configure Your Ide With the Correct Python Installation

A good configuration of an IDE like VS Code will prevent an error when you’re using Flask in VS Code. As we said earlier, you need to ensure that VS Code is using the Python version that has Flask installed. The following is how to do it.

1. Ensure you have Flask installed in the Python version that you want to use. If not, install Flask using “pip install flask” for “Python 2” or “pip3 install flask” for “Python 3”.
2. Launch VS Code and open the “Command Palette” using “Ctrl”, “Shift” and “P”.
3. Run the command “Python: Select Interpreter”.
4. Choose your Python installation that has Flask.

– Ensure the “Site-packages” Exists in Python Environment

The “site-packages” folder is where Python stores the packages that you download via the “pip” package manager. Any modification to this folder name will prevent Python from using any of its stored packages, including Flask. Now, do the following to ensure the “site-packages” exists on your Python installation:

1. Search for your Python installation folder.
2. Locate the “Lib” folder and search for the “site-packages” folder.
3. Ensure the name is “site-packages”, with no capital letters, and no punctuations.
4. Check the folder attributes and confirm that it’s not read-only.

Conclusion

In this article, we explained factors that will prevent Python from importing the Flask module or any of its plugins. Afterward, we detailed different ways that’ll fix the issue and you should remember the following:

• If you don’t have Flask installed in your Python installation, you can’t import it into your project.
• Multiple Python installations can cause the flask import error because it might not exist in the Python that you’re using.
• The Python version that your IDE is using does not contain Flask, so you’ll get the Flask import error.
• You can fix the flask import error by installing Flask for “Python 2” or “Python 3” using “pip install flask” or “pip3 install flask”.
• Imports are case-sensitive in Python, so always import them as small letters to prevent an import error.

It’s easy to use Flask and its plugins in Python, and this article shows you how to do it. The trick to prevent this error in the future: always confirm that Flask exists in your Python installation.

References

• https://peps.python.org/pep-0008/#package-and-module-names
• https://docs.python.org/3/library/venv.html
• https://the-hitchhikers-guide-to-packaging.readthedocs.io/en/latest/introduction.html
• https://anaconda.org/anaconda/flask
• https://code.visualstudio.com/docs/python/environments