Flask is one of the most popular web frameworks in Python, utilized for developing web applications. With Flask, you can create web applications that are very simple yet powerful and scalable. One of the attractive features of Flask is the use of Blueprints, which allows you to modularize your application for better organization and manageability.
Recently, Flask has introduced version 3.0. In this version, new features have been added and many behaviors have been refined. One of the notable improvements is the teardown_app_request() feature in Blueprints. This method allows you to handle a specific context at the end of processing each web request, which is extremely useful for resource cleanup after every request.
Additionally, we will explore the implementation and use of Blueprint and teardown_app_request() in a sample project using Flask 3.0. You will see how to effectively utilize these capabilities for managing requests and improving the application's performance.
In this project, we will create a simple application that includes two separate Blueprints for managing different sections of the application and utilizes teardown_app_request for resource cleanup after each request.
Sample Code Using Blueprint and teardown_app_request
from flask import Flask, Blueprint, request, g
# Define a Flask application
app = Flask(__name__)
# Create a new Blueprint
simple_bp = Blueprint('simple', __name__)
# Define a route in the Blueprint
@simple_bp.route('/')
def index():
return "Hello, Flask 3.0 Blueprint!"
# Use teardown in the Blueprint
@simple_bp.teardown_app_request
def teardown_request(exception):
if exception:
print("Exception occurred: ", exception)
else:
print("Teardown request: closing resources")
# Here you can close resources that were opened for each request
# Register the Blueprint in the main application
app.register_blueprint(simple_bp)
if __name__ == '__main__':
app.run(debug=True)
Line-by-Line Explanation of the Code
from flask import Flask, Blueprint, request, g
This line imports the necessary classes from the Flask module to use in the application.
app = Flask(__name__)
This line creates a new instance of the Flask application with the current module name as the identifier.
simple_bp = Blueprint('simple', __name__)
This line creates a new Blueprint named 'simple'.
@simple_bp.route('/')
This line defines a new route in the simple Blueprint that connects to the index function.
def index():
This function returns the string "Hello, Flask 3.0 Blueprint!" for requests to this route.
@simple_bp.teardown_app_request
This decorator specifies that the following function will be used to handle request teardown in the Blueprint.
def teardown_request(exception):
This function receives any exceptions that occur during request processing.
if exception:
It checks if there was an exception during the request processing.
print("Exception occurred: ", exception)
If an exception occurred, it prints the exception message.
else:
If no exception occurred, it indicates that resources can be cleaned up.
print("Teardown request: closing resources")
This message indicates the end of request processing and is helpful for resource management.
app.register_blueprint(simple_bp)
This line registers the created Blueprint in the Flask application.
if __name__ == '__main__':
Ensures that this block of code runs only if the script is executed directly.
app.run(debug=True)
This line starts the Flask application in debug mode, which is useful for development and testing.