From flask import flask ошибка

ImportError: cannot import name ‘Flask’ from partially initialized module

ImportError: cannot import name ‘Flask’ from partially initialized module ‘flask’ (most likely due to a circular import)

Эта ошибка возникает если Вы назвали свой файл flask.py. Переименуйте его во что-нибудь другое — например app.py

FileNotFoundError: [Errno 2] No such file or directory:

FileNotFoundError: [Errno 2] No such file or directory:

with open('C:UsersAndreiPycharmProjectsaredel_comaredel_com_venvaredel.json','r') as f:

UnicodeDecodeError: ‘charmap’ codec can’t decode byte 0x81 in position 69:

UnicodeDecodeError: ‘charmap’ codec can’t decode byte 0x81 in position 69: character maps to <undefined>

Скорее всего у вас в файле русский текст, а поддержка русского языка не подключена.

ModuleNotFoundError: No module named ‘flaskr.flaskr’

ModuleNotFoundError: No module named ‘flaskr.flaskr’

When using Python, a common error you may encounter is modulenotfounderror: no module named ‘flask’. This error occurs when Python cannot detect the Flask library in your current environment. Flask does not come with the default Python installation. This tutorial goes through the exact steps to troubleshoot this error for the Windows, Mac and Linux operating systems.

ModuleNotFoundError: no module named ‘flask’

What is ModuleNotFoundError?

The ModuleNotFoundError occurs when the module you want to use is not present in your Python environment. There are several causes of the modulenotfounderror:

The module’s name is incorrect, in which case you have to check the name of the module you tried to import. Let’s try to import the re module with a double e to see what happens:

import ree

---------------------------------------------------------------------------
ModuleNotFoundError                       Traceback (most recent call last)
1 import ree

ModuleNotFoundError: No module named 'ree'

To solve this error, ensure the module name is correct. Let’s look at the revised code:

import re

print(re.__version__)

2.2.1

You may want to import a local module file, but the module is not in the same directory. Let’s look at an example package with a script and a local module to import. Let’s look at the following steps to perform from your terminal:

mkdir example_package

cd example_package

mkdir folder_1

cd folder_1

vi module.py

Note that we use Vim to create the module.py file in this example. You can use your preferred file editor, such as Emacs or Atom. In module.py, we will import the re module and define a simple function that prints the re version:

import re

def print_re_version():

    print(re.__version__)

Close the module.py, then complete the following commands from your terminal:

cd ../

vi script.py

Inside script.py, we will try to import the module we created.

import module

if __name__ == '__main__':

    mod.print_re_version()

Let’s run python script.py from the terminal to see what happens:

ModuleNotFoundError: No module named 'module'

To solve this error, we need to point to the correct path to module.py, which is inside folder_1. Let’s look at the revised code:

import folder_1.module as mod

if __name__ == '__main__':

    mod.print_re_version()

When we run python script.py, we will get the following result:

2.2.1

Lastly, you can encounter the modulenotfounderror when you import a module that is not installed in your Python environment.

What is Flask?

Flask is a lightweight web framework written in Python. It does not automatically come installed with Python. The simplest way to install Flask is to use the package manager for Python called pip. The following instructions to install Flask are for the major Python version 3.

How to install Flask on Windows Operating System

You can install pip on Windows by downloading the installation package, opening the command line and launching the installer. You can install pip via the CMD prompt by running the following command.

python get-pip.py

You may need to run the command prompt as administrator. Check whether the installation has been successful by typing.

pip --version

To install Flask with pip, run the following command from the command prompt.

pip3 install flask

How to install Flask on Mac Operating System

Open a terminal by pressing command (⌘) + Space Bar to open the Spotlight search. Type in terminal and press enter. To get pip, first ensure you have installed Python3:

python3 --version

Python 3.8.8

Download pip by running the following curl command:

curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py

The curl command allows you to specify a direct download link. Using the -o option sets the name of the downloaded file.

Install pip by running:

python3 get-pip.py

From the terminal, use pip3 to install Flask:

pip3 install flask

How to install Flask on Linux Operating System

All major Linux distributions have Python installed by default. However, you will need to install pip. You can install pip from the terminal, but the installation instructions depend on the Linux distribution you are using. You will need root privileges to install pip. Open a terminal and use the commands relevant to your Linux distribution to install pip.

Installing pip for Ubuntu, Debian, and Linux Mint

sudo apt install python-pip3

Installing pip for CentOS 8 (and newer), Fedora, and Red Hat

sudo dnf install python-pip3

Installing pip for CentOS 6 and 7, and older versions of Red Hat

sudo yum install epel-release

sudo yum install python-pip3

Installing pip for Arch Linux and Manjaro

sudo pacman -S python-pip

Installing pip for OpenSUSE

sudo zypper python3-pip

Once you have installed pip, you can install flask using:

pip3 install flask

Check Flask Version

Once you have successfully installed Flask, you can use two methods to check the version of Flask. First, you can use pip show from your terminal.

pip show flask

Name: Flask
Version: 1.1.2
Summary: A simple framework for building complex web applications.
Home-page: https://palletsprojects.com/p/flask/
Author: Armin Ronacher
Author-email: [email protected]
License: BSD-3-Clause
Location: /Users/Yusufu.Shehu/opt/anaconda3/lib/python3.8/site-packages
Requires: Werkzeug, Jinja2, itsdangerous, click
Required-by: 

Second, within your python program, you can import Flask and then reference the __version__ attribute:

import flask

print(flask.__version__

1.1.2

Installing Flask Using Anaconda

Anaconda is a distribution of Python and R for scientific computing and data science. You can install Anaconda by going to the installation instructions. Once you have installed Anaconda, you can install flask using the following command:

conda install -c anaconda flask

Testing Flask

Once you install Flask, you can test it by writing a hello world script. To do this, first, create a file called flask_test.py and add the code below to the file:

from flask import Flask

app = Flask(__name__)


@app.route('/')

def hello_world():

    return 'Hello, World!'

if __name__ == '__main__':

    app.run()

Save and close the file, then run it from the command line using:

python flask_test.py

You will get something similar to the following output:

 * Serving Flask app "flask_test" (lazy loading)
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: off
 * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)

This output informs you that you can interact with your web application by going to the above URL. Go to http://127.0.0.1:5000/, and “Hello, World!” will appear on the page.

Summary

Congratulations on reading to the end of this tutorial!

For further reading on Flask, go to the article:

• How to Solve Python ModuleNotFoundError: no module named ‘flask_cors’

Go to the online courses page on Python to learn more about Python for data science and machine learning.

Have fun and happy researching!

If you are getting “ImportError: No module named flask” while running python flask hello world application, then follow this tutorial to resolve the error.

[email protected]:~/mypythonproj (sneppets-gcp)$ python app.py
********************************************************************************
Python command will soon point to Python v3.7.3.

Python 2 will be sunsetting on January 1, 2020.
See http://https://www.python.org/doc/sunset-python-2/

Until then, you can continue using Python 2 at /usr/bin/python2, but soon
/usr/bin/python symlink will point to /usr/local/bin/python3.

To suppress this warning, create an empty ~/.cloudshell/no-python-warning file.
The command will automatically proceed in  seconds or on any key.
********************************************************************************
Traceback (most recent call last):
  File "app.py", line 1, in <module>
    from flask import Flask
ImportError: No module named flask

Check flask installed or not

Whenever you get error “ImportError: No module named flask” first check whether flask is installed or not. The easiest way to check is go to ‘python terminal’ or ‘command prompt’ and try the following command >>> import flask

[email protected]:~/mypythonproj(sneppets-gcp)$ python
********************************************************************************
Python 2.7.13 (default, Sep 26 2018, 18:42:22)
[GCC 6.3.0 20170516] on linux2
Type "help", "copyright", "credits" or "license" for more information.

>>> import flask

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named flask

The above results clearly shows that flask module in not installed.

Create Virtual Environment

Note, different python applications uses packages and modules that’s not included in standard library. Also sometimes applications requires specific version of a library.

To meet the above requirement python supports virtual environments and packages. Virtual environment is a self contained directory that contains python installation for specific version of python and other supporting packages and libraries. Different applications can use different virtual environments.

The module used to create and manage virtual environments is called as venv. To install python3-venv  run the following command.

$ sudo apt install python3-venv
The following additional packages will be installed:
  python3.5-venv
The following NEW packages will be installed:
  python3-venv python3.5-venv
0 upgraded, 2 newly installed, 0 to remove and 17 not upgraded.
---------------------------------------------
---------------------------------------------

To create new virtual environment run the following command

$ sudo python3 -m venv venv
$ ls
app.py venv

The above command creates a directory called venv , which contains a copy of python binary, pip package manager and other supporting files needed.

$ cd venv/
$ ls
bin  include  lib  lib64  pyvenv.cfg

You need to activate the virtual environment in order to use it. So activate the virtual environment using the following command. Once activated, you would see shell prompt will change and it will show the name of the virtual environment that you are currently using. In our case it is venv.

$ source venv/bin/activate
(venv) $

Install Flask to resolve Flask ImportError

In the above steps we activated the virtual environment, now use Python package manager pip to install Flask as shown below.

(venv) $ sudo pip install flask

Collecting flask
  Downloading Flask-1.1.1-py2.py3-none-any.whl (94 kB)
     |████████████████████████████████| 94 kB 2.8 MB/s
Requirement already satisfied: Werkzeug>=0.15 in /usr/local/lib/python2.7/dist-packages (from flask) (0.16.1)
Requirement already satisfied: click>=5.1 in /usr/local/lib/python2.7/dist-packages (from flask) (7.0)
Collecting itsdangerous>=0.24
  Downloading itsdangerous-1.1.0-py2.py3-none-any.whl (16 kB)
Collecting Jinja2>=2.10.1
  Downloading Jinja2-2.11.0-py2.py3-none-any.whl (126 kB)
     |████████████████████████████████| 126 kB 19.4 MB/s
Collecting MarkupSafe>=0.23
  Downloading MarkupSafe-1.1.1-cp27-cp27mu-manylinux1_x86_64.whl (24 kB)
Installing collected packages: itsdangerous, MarkupSafe, Jinja2, flask
Successfully installed Jinja2-2.11.0 MarkupSafe-1.1.1 flask-1.1.1 itsdangerous-1.1.0

Verify the installation

To verify the installation try running the following command to check the Flask version.

(venv) $ sudo python -m flask --version

Python 2.7.13
Flask 1.1.1
Werkzeug 0.16.1

Now try running the minimal flask application that you had created. It should run without any errors now.

(venv) $ sudo python app.py

 * Serving Flask app "app" (lazy loading)
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: off
 * Running on http://0.0.0.0:5000/ (Press CTRL+C to quit)

Deactivate virtual environment

Once you are done with running your application, you can deactivate the virtual environment by typing the command deactivate to return back to normal shell

(venv)$ deactivate
$

Further Learning

• How to run a Jupyter Notebook .ipynb file from terminal or cmd prompt ?
• Check if object is null using Objects class static utility methods
• Terraform tutorial
• Convert from ZonedDateTime to LocalDateTime with a timezone

References

• Python Documentation venv
• GCP Python

Quick Fix: Python raises the ImportError: No module named 'flask' when it cannot find the library flask. The most frequent source of this error is that you haven’t installed flask explicitly with pip install flask. Alternatively, you may have different Python versions on your computer, and flask is not installed for the particular version you’re using.

Problem Formulation

You’ve just learned about the awesome capabilities of the flask library and you want to try it out, so you start your code with the following statement:

import flask

This is supposed to import the Pandas library into your (virtual) environment. However, it only throws the following ImportError: No module named flask:

>>> import flask
Traceback (most recent call last):
  File "<pyshell#6>", line 1, in <module>
    import flask
ModuleNotFoundError: No module named 'flask'

Solution Idea 1: Install Library flask

The most likely reason is that Python doesn’t provide flask in its standard library. You need to install it first!

Before being able to import the Pandas module, you need to install it using Python’s package manager pip. Make sure pip is installed on your machine.

To fix this error, you can run the following command in your Windows shell:

$ pip install flask

This simple command installs flask in your virtual environment on Windows, Linux, and MacOS. It assumes that your pip version is updated. If it isn’t, use the following two commands in your terminal, command line, or shell (there’s no harm in doing it anyways):

$ python -m pip install --upgrade pip
$ pip install pandas

💡 Note: Don’t copy and paste the $ symbol. This is just to illustrate that you run it in your shell/terminal/command line.

Solution Idea 2: Fix the Path

The error might persist even after you have installed the flask library. This likely happens because pip is installed but doesn’t reside in the path you can use. Although pip may be installed on your system the script is unable to locate it. Therefore, it is unable to install the library using pip in the correct path.

To fix the problem with the path in Windows follow the steps given next.

Step 1: Open the folder where you installed Python by opening the command prompt and typing where python

Step 2: Once you have opened the Python folder, browse and open the Scripts folder and copy its location. Also verify that the folder contains the pip file.

Step 3: Now open the Scripts directory in the command prompt using the cd command and the location that you copied previously.

Step 4: Now install the library using pip install flask command. Here’s an analogous example:

After having followed the above steps, execute our script once again. And you should get the desired output.

Other Solution Ideas

• The ModuleNotFoundError may appear due to relative imports. You can learn everything about relative imports and how to create your own module in this article.
• You may have mixed up Python and pip versions on your machine. In this case, to install flask for Python 3, you may want to try python3 -m pip install flask or even pip3 install flask instead of pip install flask
• If you face this issue server-side, you may want to try the command pip install --user flask
• If you’re using Ubuntu, you may want to try this command: sudo apt install flask
• You can check out our in-depth guide on installing flask here.
• You can also check out this article to learn more about possible problems that may lead to an error when importing a library.

Understanding the “import” Statement

import flask

In Python, the import statement serves two main purposes:

• Search the module by its name, load it, and initialize it.
• Define a name in the local namespace within the scope of the import statement. This local name is then used to reference the accessed module throughout the code.

What’s the Difference Between ImportError and ModuleNotFoundError?

What’s the difference between ImportError and ModuleNotFoundError?

Python defines an error hierarchy, so some error classes inherit from other error classes. In our case, the ModuleNotFoundError is a subclass of the ImportError class.

You can see this in this screenshot from the docs:

You can also check this relationship using the issubclass() built-in function:

>>> issubclass(ModuleNotFoundError, ImportError)
True

Specifically, Python raises the ModuleNotFoundError if the module (e.g., flask) cannot be found. If it can be found, there may be a problem loading the module or some specific files within the module. In those cases, Python would raise an ImportError.

If an import statement cannot import a module, it raises an ImportError. This may occur because of a faulty installation or an invalid path. In Python 3.6 or newer, this will usually raise a ModuleNotFoundError.

Related Videos

The following video shows you how to resolve the ImportError:

The following video shows you how to import a function from another folder—doing it the wrong way often results in the ModuleNotFoundError:

How to Fix “ModuleNotFoundError: No module named ‘flask’” in PyCharm

If you create a new Python project in PyCharm and try to import the flask library, it’ll raise the following error message:

Traceback (most recent call last):
  File "C:/Users/.../main.py", line 1, in <module>
    import flask
ModuleNotFoundError: No module named 'flask'

Process finished with exit code 1

The reason is that each PyCharm project, per default, creates a virtual environment in which you can install custom Python modules. But the virtual environment is initially empty—even if you’ve already installed flask on your computer!

Here’s a screenshot exemplifying this for the pandas library. It’ll look similar for flask.

The fix is simple: Use the PyCharm installation tooltips to install Pandas in your virtual environment—two clicks and you’re good to go!

First, right-click on the pandas text in your editor:

Second, click “Show Context Actions” in your context menu. In the new menu that arises, click “Install Pandas” and wait for PyCharm to finish the installation.

The code will run after your installation completes successfully.

As an alternative, you can also open the Terminal tool at the bottom and type:

$ pip install flask

If this doesn’t work, you may want to set the Python interpreter to another version using the following tutorial: https://www.jetbrains.com/help/pycharm/2016.1/configuring-python-interpreter-for-a-project.html

You can also manually install a new library such as flask in PyCharm using the following procedure:

• Open File > Settings > Project from the PyCharm menu.
• Select your current project.
• Click the Python Interpreter tab within your project tab.
• Click the small + symbol to add a new library to the project.
• Now type in the library to be installed, in your example Pandas, and click Install Package.
• Wait for the installation to terminate and close all popup windows.

Here’s an analogous example:

Here’s a full guide on how to install a library on PyCharm.

• How to Install a Library on PyCharm