Key points in parsing HTTP status codes

Analysis of the key points of HTTP status code setting, specific code examples are required

In the process of web development, it is very important to master the setting of HTTP status code. HTTP status code is a kind of information returned to the client when the web server responds to the request. It uses three digits to represent different statuses. This article will analyze the key points of setting HTTP status codes and provide some specific code examples to help developers better understand and apply HTTP status codes.

1. Classification of HTTP status codes

HTTP status codes are divided into five categories, which are used in different scenarios:

1. 1xx (Informational): indicates The server has received the client's request, but needs further processing or waiting.
2. 2xx (Success): Indicates that the server successfully processed the client's request and returned the corresponding content.
3. 3xx (Redirection): Indicates that the client needs to perform further operations to complete the request.
4. 4xx (Client Error): Indicates that the request sent by the client has an error and the server cannot process it.
5. 5xx (Server Error): Indicates that an error occurred while the server was processing the request.

2. Key points for setting HTTP status codes

1. Common 2xx status codes

   • 200 OK: Indicates successful processing by the server The request was made and the corresponding content was returned. This is the most common status code and is typically used in normal request responses.
   • 201 Created: Indicates that the server successfully processed the request and created a new resource. Typically used in POST requests that create resources.
   • 204 No Content: Indicates that the server successfully processed the request but did not return any content. Typically used for requests that do not require content to be returned.

2. Common 3xx status codes

   • 301 Moved Permanently: Indicates that the requested resource has been permanently moved to a new URL. The search engine updates its index, redirecting the old URL to the new one.
   • 302 Found: Indicates that the requested resource has been temporarily moved to a new URL. The search engine does not update its index but redirects the old URL to the new URL.
   • 304 Not Modified: Indicates that the client's cached resources are still valid and the cached resources can be used directly without requesting the server again.

3. Common 4xx status codes

   • 400 Bad Request: Indicates that the request sent by the client has a syntax error and the server cannot understand it.
   • 401 Unauthorized: Indicates that the request requires user authentication, but the user did not provide valid authentication information.
   • 403 Forbidden: Indicates that the server refuses to execute the request and does not have permission to access the requested resource.
   • 404 Not Found: Indicates that the requested resource does not exist.

4. Common 5xx status codes

   • 500 Internal Server Error: Indicates that an unknown error occurred while the server was processing the request.
   • 502 Bad Gateway: Indicates that the server, acting as a gateway or proxy server, received an invalid response.
   • 503 Service Unavailable: Indicates that the server is currently unable to process the request, possibly due to overload or maintenance.

3. Specific code examples

The following are specific code examples of some common HTTP status codes to help developers better understand and apply HTTP status codes setting.

1. Return 200 OK status code example:

from flask import Flask, jsonify

app = Flask(__name__)

@app.route('/')
def index():
    return jsonify({'message': 'Hello World'}), 200

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

2. Return 301 Moved Permanently status code example:

from flask import Flask, redirect

app = Flask(__name__)

@app.route('/old-url')
def old_url():
    return redirect('/new-url', code=301)

@app.route('/new-url')
def new_url():
    return 'This is the new URL'

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

The above is only Some common HTTP status code setting examples, developers can choose the corresponding status code to set according to their own needs.

Summary

This article analyzes the key points of setting HTTP status codes and provides some specific code examples. Mastering the settings of HTTP status codes is very important for web development, which can help developers better handle and respond to client requests. I hope the content of this article will be helpful to readers and bring some benefits.

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