How to use the flask module for web development in Python 2.x

How to use Flask module for web development in Python 2.x

Introduction:
With the rapid development of the Internet, Web development has become a very important technology in the Internet industry. In Python web development, the Flask framework is a very popular choice. It is simple, lightweight, flexible and easy to use, suitable for rapid development of small and medium-sized projects. This article will introduce how to use Flask module for web development in Python 2.x version, and give corresponding code examples.

Install Flask:
Before we start, we need to install the Flask module. You can use the pip command to install, the specific command is as follows:

pip install flask

Create a Flask application:
After installing the Flask module, we can create a simple Flask application. The code below demonstrates a minimal Flask application:

from flask import Flask

app = Flask(__name__)

@app.route('/')
def index():
    return 'Hello, Flask!'

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

In the above code, we first import the Flask module and create a Flask application instance. Next, we use  @app.route('/') the decorator to specify a URL route. When the user visits the root path in the browser,  index() the function will be called and the corresponding string will be returned. Finally, we use  app.run() the method to run the application.

Running the application:
After completing the steps to create a Flask application, we can run the application and view the result in the browser. Just run the Python script file where the above code is located, and visit http://localhost:5000 to see the 'Hello, Flask!' string.

Respond to different URLs:
The Flask framework can easily respond to different URL requests. The sample code below demonstrates how to respond to different URL requests:

@app.route('/')
def index():
    return 'Hello, Flask!'

@app.route('/about')
def about():
    return 'This is about page'

@app.route('/contact')
def contact():
    return 'Please contact us at [email protected]'

In the above code, we defined index(), about() and contact() respectively, and used different URL paths as parameters of the decorator. When the user visits different URLs, the corresponding function will be called and the corresponding string will be returned.

Passing parameters:
The Flask framework also supports passing parameters. The following sample code demonstrates how to pass parameters and operate with parameter values:

@app.route('/user/<name>')
def user(name):
    return 'Hello, {}'.format(name)

In the above code, we defined a function called user() with  <name> parameters as part of the decorator. When a user visits  /user/xxx such a URL path, xxx it will be passed as a parameter value to the user() function.

Templates and static files:
In actual web development, we usually need to use templates to render dynamic content and serve static files (such as CSS, JavaScript, images, etc.). The Flask framework also provides corresponding support. The following sample code demonstrates how to use templates and serve static files:

from flask import Flask, render_template

app = Flask(__name__)

@app.route('/')
def index():
    return render_template('index.html')

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

In the above code, we first imported  render_template the function and created a  index.html template file named . In  index() the function, we use  render_template() the function to render  index.html the template and return the rendered result.

Summary:
This article describes how to use the Flask module for web development in Python 2.x versions. By installing the Flask module, creating an application, responding to different URL requests, passing parameters, as well as using templates and serving static files, we can start simple and fast web development. Hope this article helps you!

Reference link:

• Flask official documentation: http://flask.pocoo.org/
• Flask source code repository: https://github.com/pallets/flask