Cannot setup Flask. How to setup environment varia

Question

I just started learning flask and I am stuck at setting up Flask. I don't know how to setup environment variable. Whenever I use the Flask run command, I encounter the following. I did a lot of google searches to setup environment variable on Windows but I am unable to find and somemtime not able to understand the solution. How to do this ? How to get the "app.py" or "wsgi.py" ? Please help.

command : flask run

Error message : Could not locate a Flask application. You did not provide the "FLASK_APP" environment variable, and a "wsgi.py" or "app.py" module was not found in the current directory.

error message

Answer 1

You need to actually run it from your Windows command line, NOT the built in command line for something like Visual Studio Code. Run those commands from your windows command line, in the proper directory, and everything should work.

The reason this creates problems - Visual Studio Code creates a Powershell environment for your command line. You could use the recommended $env:FLASK_APP = "your_app.py" from within the VSC environment and that will work too.

A bit late but I hope this helps others!!!

Answer 2

A step-wise solution is provided below:

1. Go to the folder where you have placed your flask app (on the command line)

2. Create a virtual environment as using the command ($ py -m venv env) here 'venv' is the short form of the virtual environment and 'env' at the end represents the name of the environment which you want (I have named it as env). Thereafter you can see at from the file explorer that a folder named 'env' is created in the folder stated at point #1 above.

3. Enter the following command ($env\Scripts\activate) by pressing enter this will turn on your virtual environment

4. Thereafter, enter the following command ($set FLASK_APP=<your app name>.py)

5. Enter the following command ($flask run)

Answer 3

you need to provide an application environment. So Flask needs to know, the .py file to run. Try to run that command

export FLASK_APP=application.py

where application.py - name of your Flask app in my case it is application.py.

after that

flask run

Answer 4

The set command works but to setup the environment, you need to make sure that you are in the right directory where the file is located. For example, if my application is hello_world.py and it is located at the venv\hello\hello_world.py, you need to make sure that you are in the right directory before setting up set FLASK_APP=hello_world.py this is for windows but in another OS, you need to use export instead set

(venv) C:\Users\myProjects\venv\hello\set FLASK_APP=hello_world.py

Answer 5

I don't think the 'flask run' command is the one which causes the error here. I got the same message error and the problem came from the fact I copied/pasted the set FLASK_APP and $env: FLASK_APP commands as written in the documentation. I had to add spaces before and after '>' or '=', and then everything worked.

Example: this command didn't work 'C:\path\to\app>set FLASK_APP=hello.py', but this one did 'C:\path\to\app > set FLASK_APP = hello.py'.

Maybe it's the same problem you have?