Understanding app.run(debug=True) in Flask

 

 app.run(debug=True) 

In our previous example, we started the Flask application using:

app.run(debug=True)

The app.run() method starts Flask's built-in development web server. Once the server starts, the application becomes accessible in a web browser, typically at:

http://127.0.0.1:5000

The debug=True parameter enables Debug Mode, which is very useful during development.

Benefits of Debug Mode

• Automatically reloads the application whenever you save changes to your Python file. You don't need to stop and restart the server manually.

• Displays detailed error messages in the browser if your application encounters an error, making it much easier to identify and fix problems.

• Speeds up development, allowing you to test changes quickly.

Note: Debug mode should only be used during development. It should be disabled (debug=False) before deploying your Flask application to a production environment for security reasons.

Example

from flask import Flask

app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello Pranay, There'

@app.route('/pranay')
def text_info():
    return 'Hey there, Flask tutorial begins'

if __name__ == '__main__':
    app.run(debug=True)

When you run this program, Flask starts a local web server in debug mode. Any changes you make to the code are automatically reflected after saving the file, making development faster and more convenient.

Let me change the code and save it 

just refresh the URL http://127.0.0.1:5000/