VS Code：如何调试使用 Connexion 的 Flask 应用程序？

Question

I have faced a problem with starting a Flask app. I am trying to run the app in debug mode with Visual Studio Code but it doesn't run properly.

Here is the main module code:

import os
import sys
import logging
import argparse
import connexion
import flask
from cwsm import connexion_manager
import connector.config as lc
_CONFIG = None

path = os.path.abspath("./")

lc.initConfig(path + "/connector/config/Legic.ini")

app = connexion.FlaskApp(__name__, specification_dir=path + "/connector/config")
app.add_api("connectore.yaml")
app.run(host="0.0.0.0", port=8080,debug=True)

if __name__ == '__main__':
   main()

Here is configuration for debug from launch.json

{

        "name": "Python: Flask",
        "type": "python",
        "request": "launch",
        "module": "flask",
        "env": {
            "FLASK_APP": "application_hook:FlaskApp('dev')",
            "FLASK_ENV": "development",
            "FLASK_DEBUG": "0"
        },
        "args": [
            "run",
            "--no-debugger"
        ],
        "jinja": true
    }

The problem is, each time I run it in debug mode the program does not execute my code instead it shows this error: Error: module 'application_hook' has no attribute 'FlaskApp' Why does it happen? Thanks in advance

A litle bit more traceback:

(.venv) PS C:\Users\fele\Documents\Git>  cd 'c:\Users\fele\Documents\Git'; & 'c:\Users\fele\Documents\Git\.venv\Scripts\python.exe' 'c:\Users\fele\.vscode\extensions\ms-python.python-2020.9.112786\pythonFiles\lib\python\debugpy\launcher' '51724' '--' '-m' 'flask' 'run' '--no-debugger' 
 * Serving Flask app "application_hook:FlaskApp('dev')"
 * Environment: development
 * Debug mode: off
C:\Users\fele\Documents\Git/connector/config/Git.ini
C:\Users\fele\Documents\Git\.venv\lib\site-packages\connexion\apps\flask_app.py:96: Warning: Silently ignoring app.run() because the application is run from the flask command line executable.  Consider putting app.run() behind an if __name__ == "__main__" guard to silence this warning.
  self.app.run(self.host, port=self.port, debug=self.debug, **options)
Usage: python -m flask run [OPTIONS]

Error: module 'application_hook' has no attribute 'FlaskApp'
(.venv) PS C:\Users\fele\Documents\Git> 

Answer 1

To fix "Error: module 'application_hook' has no attribute 'FlaskApp'" , update launch.json by setting FLASK_APP to the name of the main file that launches the app (for example, app.py or main.py).

In addition, since you are using connexion , launch.json needs to be updated as follows:

• the module should be changed from flask to connexion
• args :
  • delete --no-debugger
  • add the path to your specification file
  • add --port and the port number

launch.json

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Python: Connexion",
            "type": "python",
            "request": "launch",
            "module": "connexion",
            "cwd": "${workspaceFolder}",
            "env": {
                "FLASK_APP": "app.py",
                "FLASK_ENV": "development",
                "FLASK_DEBUG": "1"
            },
            "args": [
                "run",
                "./connector/config",
                "--port",
                "8080"
            ],
            "jinja": true
        }
    ]
}

In the main module, app.run() should be placed within the __main__ guard:

Main module (app.py or main.py)

path = os.path.abspath("./")

lc.initConfig(path + "/connector/config/Legic.ini")

app = connexion.FlaskApp(__name__, specification_dir=path + "/connector/config")
app.add_api("connectore.yaml")


if __name__ == '__main__':
   app.run(host="0.0.0.0", port=8080,debug=True)

Answer 2

I don't know why!!! But, I'm working on a Flask/Connexion project. Two months ago I've struggled trying to debug that on VSCode. I gave up when it just worked as expected with zero pain on PyCharm. Now, maybe due to some Linux/VSCode?PyCharm update, the same source code is no longer 'debugable' with PyCharm and is working on VSCode with the most simple launcher:

"configurations": [
    {
        "name": "Python: Debug",
        "type": "python",
        "request": "launch",
        "program": "app.py",
        "console": "integratedTerminal"
    }
]

Don't ask me why! It's the same source code! And yes, I'm using venv.