Flask is one of the most popular web frameworks for the Python language that enables the creation of simple and straightforward websites and APIs. In version 3.0, many functions and structures of this framework have undergone beneficial improvements and simplifications. One of the most important functions in Flask applications is the Flask.run() function, which is essential for running our application.
By using Flask.run(), we can easily set up a local development server and test our application in real time. This functionality helps developers quickly observe changes made in their code and easily debug the application.
In the latest versions of Flask, using this function has changed compared to older methods like app.run(), with smaller modifications that have optimized performance and usability. These changes feature better security capabilities and faster execution in development.
One of the significant enhancements is the ability for better customization that allows developers to easily configure their application to a specific port and IP address. This way, they can have greater control over their development environment.
Furthermore, it should be noted that Flask.run is designed to be used only in development environments and is not recommended for production setups. For deploying applications on the internet, it’s better to use standard web servers like Gunicorn or uWSGI.
Example Code
from flask import Flask
app = Flask(__name__)
@app.route("/")
def home():
return "Hello, World!"
if __name__ == "__main__":
app.run(debug=True, host='0.0.0.0', port=5000)
Line-by-Line Explanation of the Code
from flask import Flask Import the Flask library.
app = Flask(__name__) Creates an instance of the Flask class using the name of the current module.
@app.route("/") Defines which URL will call the function that follows.
def home(): This function returns a response.
return "Hello, World!" Sends back the message "Hello, World!" to the caller.
if __name__ == "__main__": Checks if this script is being run directly (as opposed to being imported).
app.run(debug=True, host='0.0.0.0', port=5000) Runs the development server on port 5000 with debugging enabled.