Home Backend Development Python Tutorial How to use the flask module for web development in Python 3.x

How to use the flask module for web development in Python 3.x

Jul 29, 2023 am 10:36 AM
web development python x flask module

How to use the Flask module for Web development in Python 3.x

Introduction:
With the rapid development of the Internet, the demand for Web development is also increasing. To meet the needs of developers, many web development frameworks have emerged. Among them, Flask is a simple and practical web development framework. It is lightweight, flexible, and easy to expand. It is the first choice for many beginners and small and medium-sized projects.

This article will introduce you to how to use the Flask module in Python 3.x for web development, and provide some practical code examples.

Part One: Install Flask

Before we begin, first we need to install the Flask module. Flask can be installed from the command line using the following command:

pip install flask
Copy after login

Part 2: Create a simple Flask application

Next, we will create a simple Flask application. In this example, we will create a basic "Hello World" web page.

First, create a file named app.py in the code editor and enter the following code:

# 导入 Flask 模块
from flask import Flask

# 创建一个 Flask 应用实例
app = Flask(__name__)

# 创建一个路由,处理根目录访问
@app.route('/')
def hello_world():
    return 'Hello, world!'

# 运行应用
if __name__ == '__main__':
    app.run()
Copy after login

This code is very simple, it first imports The Flask module was installed, and then a Flask instance app was created. Next, use the decorator @app.route('/') to create a route that handles requests to access the root directory and returns a string "Hello, world!". Finally, the application is run via app.run().

After saving the code, execute the following command on the command line to run the application:

python app.py
Copy after login

If everything goes well, you will see output similar to the following:

 * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
Copy after login

At this time You can enter http://127.0.0.1:5000/ in your browser and you will see the "Hello, world!" string.

Part 3: Routing and View Functions

In the above example, we created a simple route, processed the access request to the root directory, and returned a string. Now we'll cover more about routing and view functions.

Flask supports using different URL rules to define routes. Routes can be defined using the decorator @app.route. Here is an example:

# 创建一个路由,处理 /hello 路径的 GET 请求
@app.route('/hello')
def hello():
    return 'Hello, Flask!'
Copy after login

In this example, @app.route('/hello') defines a route that will handle GET requests accessing the /hello path, and Returns the string "Hello, Flask!".

View functions are functions that process requests and return responses. In the above example, hello() is a view function.

Part 4: Requests and Responses

In web development, requests and responses are very important concepts. Flask provides multiple ways to handle requests and responses.

Through the request object, you can access request-related information, such as path, parameters, form data, etc. Here is an example:

from flask import request

# 创建一个路由,处理 /search 路径的 GET 请求
@app.route('/search')
def search():
    keyword = request.args.get('keyword', '')  # 获取查询参数 keyword
    return 'You are searching for: ' + keyword
Copy after login

In this example, we use the request.args.get() method to get the value of the query parameter keyword and return a string.

To return a response, you can use the return statement or the make_response() function. Here is an example:

from flask import make_response

@app.route('/cookie')
def cookie():
    response = make_response('This is a cookie page.')
    response.set_cookie('username', 'john')  # 设置一个名为 username 的 cookie
    return response
Copy after login

In this example, we create a response object using the make_response() function and set it using the response.set_cookie() method A cookie named username is created.

Part 5: Template Engine

In actual Web development, we usually need to dynamically generate HTML pages. In order to easily implement this function, Flask provides a template engine.

When using a template engine, we can separate HTML code and dynamic content, making the code easier to maintain and develop. Here is an example using a template engine:

from flask import render_template

@app.route('/user/<username>')
def profile(username):
    return render_template('profile.html', name=username)
Copy after login

In this example, we use the render_template() function to render the template profile.html and pass the parameters ## The value of #username is passed to the template. In templates, you can use the {{ name }} syntax to output dynamic content.

Conclusion:

This article introduces how to use the Flask module for web development in Python 3.x and provides some practical code examples. I hope readers can understand the basic usage of Flask through this article, and can further learn and explore more functions of the Flask framework. I wish you all success in web development!

The above is the detailed content of How to use the flask module for web development in Python 3.x. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Python web development framework comparison: Django vs Flask vs FastAPI Python web development framework comparison: Django vs Flask vs FastAPI Sep 28, 2023 am 09:18 AM

Python web development framework comparison: DjangovsFlaskvsFastAPI Introduction: In Python, a popular programming language, there are many excellent web development frameworks to choose from. This article will focus on comparing three popular Python web frameworks: Django, Flask and FastAPI. By comparing their features, usage scenarios and code examples, it helps readers better choose the framework that suits their project needs. 1. Django

Reimagining Architecture: Using WordPress for Web Application Development Reimagining Architecture: Using WordPress for Web Application Development Sep 01, 2023 pm 08:25 PM

In this series, we will discuss how to build web applications using WordPress. Although this is not a technical series where we will look at code, we cover topics such as frameworks, fundamentals, design patterns, architecture, and more. If you haven’t read the first article in the series, I recommend it; however, for the purposes of this article, we can summarize the previous article as follows: In short, software can be built on frameworks, software can Extend the base. Simply put, we distinguish between framework and foundation—two terms that are often used interchangeably in software, even though they are not the same thing. WordPress is a foundation because it is an application in itself. It's not a framework. For this reason, when it comes to WordPress

How to use the urllib.parse.unquote() function to decode URLs in Python 3.x How to use the urllib.parse.unquote() function to decode URLs in Python 3.x Aug 02, 2023 pm 02:25 PM

How to use the urllib.parse.unquote() function to decode URLs in Python 3.x. In Python's urllib library, the urllib.parse module provides a series of tool functions for URL encoding and decoding, among which urllib.parse.unquote() Functions can be used to decode URLs. This article will introduce how to use urllib.parse.un

How to use the math module to perform mathematical operations in Python 3.x How to use the math module to perform mathematical operations in Python 3.x Aug 01, 2023 pm 03:15 PM

How to use the math module to perform mathematical operations in Python 3.x Introduction: In Python programming, performing mathematical operations is a common requirement. In order to facilitate processing of mathematical operations, Python provides the math library, which contains many functions and constants for mathematical calculations and mathematical functions. This article will introduce how to use the math module to perform common mathematical operations and provide corresponding code examples. 1. Basic mathematical operation addition is performed using the function math.add() in the math module.

What are the advantages and disadvantages of C++ compared to other web development languages? What are the advantages and disadvantages of C++ compared to other web development languages? Jun 03, 2024 pm 12:11 PM

The advantages of C++ in web development include speed, performance, and low-level access, while limitations include a steep learning curve and memory management requirements. When choosing a web development language, developers should consider the advantages and limitations of C++ based on application needs.

How to get started with web development using C++? How to get started with web development using C++? Jun 02, 2024 am 11:11 AM

To use C++ for web development, you need to use frameworks that support C++ web application development, such as Boost.ASIO, Beast, and cpp-netlib. In the development environment, you need to install a C++ compiler, text editor or IDE, and web framework. Create a web server, for example using Boost.ASIO. Handle user requests, including parsing HTTP requests, generating responses, and sending them back to the client. HTTP requests can be parsed using the Beast library. Finally, a simple web application can be developed, such as using the cpp-netlib library to create a REST API, implementing endpoints that handle HTTP GET and POST requests, and using J

What skills and resources are needed to learn C++ web development? What skills and resources are needed to learn C++ web development? Jun 01, 2024 pm 05:57 PM

C++ Web development requires mastering the basics of C++ programming, network protocols, and database knowledge. Necessary resources include web frameworks such as cppcms and Pistache, database connectors such as cppdb and pqxx, and auxiliary tools such as CMake, g++, and Wireshark. By learning practical cases, such as creating a simple HTTP server, you can start your C++ Web development journey.

What are the common application scenarios of Golang in software development? What are the common application scenarios of Golang in software development? Dec 28, 2023 am 08:39 AM

As a development language, Golang has the characteristics of simplicity, efficiency, and strong concurrency performance, so it has a wide range of application scenarios in software development. Some common application scenarios are introduced below. Network programming Golang is excellent in network programming and is particularly suitable for building high-concurrency and high-performance servers. It provides a rich network library, and developers can easily program TCP, HTTP, WebSocket and other protocols. Golang's Goroutine mechanism allows developers to easily program

See all articles