The default launch configuration in VS Code for Flask is a great help. However, there is one little optimisation that massively improves your development experience.
This post is part of my journey to learn Python. You can find the other parts of this series here.
Activate auto-reload
When you are writing your code, you make changes and want to see them in the browser. VS Code allows you to change your code while you run the debugger, but the default launch configuration requires you to stop and start the debugger before you can see your change. We can get rid of this extra step with 2 changes in the launch.json file:
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{ // Use IntelliSense to learn about possible attributes. // Hover to view descriptions of existing attributes. // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387 "version": "0.2.0", "configurations": [ { "name": "Python: Flask", "type": "python", "request": "launch", "module": "flask", "env": { "FLASK_APP": "hello.py", "FLASK_ENV": "development", "FLASK_DEBUG": "1" }, "args": [ "run", "--no-debugger" ], "jinja": true } ] } |
On line 15 we activated FLASK_DEBUG by switching the value from 0 to 1. In the args dictionary we need to remove the option “–no-reload” (that is in the original launch.json file in line 20).
If we now make a change and save our file, Flask will detect the change and automatically restart the server:
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* Detected change in 'D:\\_Flask_Demo\\hello.py', reloading * Restarting with stat * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit) |
All we need to do is to hit reload in our browser.
Conclusion
With this little change we can develop without constantly restarting the web server. This will help us a lot when we add more features to our application.
Sorry, where is this launch.json file?
Hi newbie,
If you follow along the Flask and VS Code tutorial from https://code.visualstudio.com/docs/python/tutorial-flask#_run-the-app-in-the-debugger (step 2 creates the launch.json file), the launch.json file will be in the .vscode folder in the top level folder of your project.
Regards,
Johnny