SoFunction
Updated on 2024-11-19

Python Requests Library and Usage in Detail

Hello everyone, Communicating with a web server is a crucial task in modern web development.Python, a versatile programming language, offers a variety of tools and libraries to simplify this process. One of the most popular HTTP libraries in Python, the Requests library, provides developers with a simple yet powerful way to send HTTP requests and process responses.

From the most basic GET requests to complex authentication and proxy settings , Requests library provides us with a rich set of features and flexible interfaces . Whether it is a crawler , Web development or testing , Requests is an indispensable tool .

In this article, we will take you on a deep dive into the world of the Python Requests library. We'll start with the basics and work our way through, covering a variety of advanced uses and techniques. Whether you are a beginner or an experienced developer, this article will provide you with valuable information and practical tips to help you better utilize the Python Requests library to build powerful web applications.

I. Introduction

In modern web communication, sending HTTP requests and handling responses is one of the common tasks in programming. And the Requests library in Python provides developers with a simple, elegant and feature-rich way to handle these tasks.

What are Requests?

Requests is an elegant and clean HTTP library designed specifically for sending various types of HTTP requests. It was created by Kenneth Reitz in 2010 and has quickly become one of the most popular HTTP client libraries in the Python community.The Requests library is built on Python's standard libraryurllibOn top of that, a cleaner and more user-friendly interface is provided.

The Role of the Requests Library

The main role of the Requests library is to simplify the sending of HTTP requests and the processing of responses. With Requests, developers can easily execute various types of HTTP requests such as GET, POST, PUT, DELETE, etc. and process the response data returned by the server. Not only that , Requests also provides many convenient features , such as automatic handling of redirects , session management , authentication , proxy settings , etc. , making network communication easier and more flexible .

Why is the Requests library so popular?

The reason why the Requests library is so popular is because it has several significant advantages:

simple and easy to use: Requests provides a clean and intuitive API that makes sending HTTP requests very easy. Developers do not need to deal with complex details , just a few lines of code to complete common network communication tasks .

feature-rich: Although Requests provides a simple interface, it also offers many powerful features and advanced options that fulfill the needs of a variety of complex scenarios. Whether you're dealing with sessions, handling redirects, performing authentication or setting up proxies, Requests can do it all with ease.

Fully documented: Requests has clear, detailed official documentation that covers all aspects of the library, including basic usage, advanced features, sample code, and more. This makes it easy for developers to access the documentation and solve problems.

Active community support: The Requests library has a large and active community where developers can get timely help and support. Whether it's asking questions, reporting bugs, or contributing code, the community is an invaluable resource.

The Requests library has become popular in Python development due to its simplicity, rich functionality, and support from an active community. It has become the tool of choice for many developers to handle HTTP requests, saving them a lot of time and effort.

II. Installation

Installing the Requests library is the first step to start using it. In this section, we will explain in detail how to install the Requests library and provide some installation problems you may encounter and their solutions.

1. Installation using pip

In most cases, installing the Requests library using pip, Python's package management tool, is the easiest way. If you are using Python 3, pip is usually already included with the Python installation. Here are the commands to install the Requests library:

pip install requests

2. Installation using conda

If you are using the Anaconda Python distribution, you can also use conda to install the Requests library:

conda install requests

3. Possible installation problems and solutions

Although installing the Requests library is usually a simple task, sometimes you may run into some problems. Here are some possible installation problems and their solutions:

Issue 1: SSL certificate validation failure

Sometimes when installing the Requests library there may be a problem with SSL certificate validation failing, this may be due to a lack of a proper SSL certificate or a problem with the network environment.

prescription: You can try disabling SSL certificate validation during installation. During pip installation, you can disable SSL certificate validation using the--trusted-hostparameter, as shown below:

pip install --trusted-host  --trusted-host  --trusted-host= requests

Issue 2: Slow or failed installation process

Sometimes the installation process may become slow or fail due to network problems or server issues.

prescription: You can try changing the mirror source for pip to speed up the installation process, or try running the install command multiple times to resolve the server issue.

Issue 3: Competence issues

In some operating systems, the installation may fail due to permission issues.

prescription: You can try to use administrator rights or use a virtual environment to avoid permission issues.

Issue 4: Dependency conflicts

Sometimes installing the Requests library may conflict with other dependencies.

prescription: You can try upgrading or downgrading pip, Python or other related dependency packages to resolve dependency conflicts.

Send basic GET and POST requests.

The two most common types of HTTP requests in web communication are GET requests and POST requests.GET requests are used to get resources from the server, while POST requests are used to submit data to the server. In this section, we will demonstrate how to send the most basic GET and POST requests using the Requests library and explain the differences between them.

1. Send a GET request

Sending GET requests using the Requests library is very simple. You just need to use the()function and just pass in the target URL. Here is a simple example:

import requests
# Send GET request
response = ('/data')
# Print the response
print()

The above code sends a GET request to the/data, and printed the contents of the server response.

2. Sending POST requests

Similar to GET requests, sending a POST request is very simple. You just need to use the()function, and just pass in the target URL and the data to be submitted. Here is a simple example:

import requests
# of data to be submitted
data = {'username': 'user', 'password': '123456'}
# Send POST request
response = ('/login', data=data)
# Print the response
print()

The code above sends a POST request to the/login, and submits the username and password data. The server receives the data, processes it, and returns the appropriate response.

3. Differences between GET and POST requests

The main difference between a GET request and a POST request is the way the data is transferred and the security:

  • GET request: Data is passed via URL parameters, which appear in plaintext in the URL and are therefore not suitable for transmitting sensitive information.GET requests are usually used to fetch resources, such as web pages, images, etc.
  • POST request: The data is passed through the request body, and the data is transmitted in the form of cipher text, so it is more secure and suitable for transmitting sensitive information.POST requests are usually used to submit data to the server, such as user login, form submission, etc.

In general, GET request is suitable for getting resources, while POST request is suitable for submitting data. In actual development, you need to choose the appropriate request method according to the specific needs.

IV. Request headers and request bodies

When sending an HTTP request, you can set the request header and request body in addition to the URL. The request header is used to pass some additional information to the server, such as user agent, authorization information, etc. The request body is used to submit data to the server, such as form data, JSON data, and so on. In this section, we will explain in detail how to set the request header and request body and explain their roles.

1. Setting the request header

Setting up request headers with the Requests library is very simple, you just need to pass a dictionary to theheadersparameter is sufficient. Here is an example:

import requests
# Set request headers
headers = {
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36',
    'Authorization': 'Bearer your_access_token'
}
# Send GET requests with customized request headers
response = ('/data', headers=headers)
# Print the response
print()

The code above sets up two common request headers:User-Agentfor specifying a user agent.AuthorizationUsed for authentication. You can set other request headers as needed.

2. Setting up the request body

When sending a POST request, you can pass thedataparameter sets the request body, passing the data to be submitted. If you want to send JSON data, you can use thejsonparameters. The following is an example:

import requests
# of data to be submitted
data = {
    'username': 'user',
    'password': '123456'
}
# Send a POST request with a request body
response = ('/login', data=data)
# Print the response
print()

The above code sets up a request body containing username and password data. When the server receives the data, it processes it and returns the appropriate response.

3. Role of request headers and request bodies

  • request header: The request header contains some additional information that is used to tell the server some extra information about the request, such as the client type, the type of data to be accepted, and so on. It can be used to implement functions such as user agent identification, authentication, setting cookies, etc.
  • requestor: The request body is used to submit data to the server, such as form data, JSON data, etc. It is usually used to send data to the server that needs to be processed, such as user login information, search keywords and so on.

Overall, both the request header and request body are important parts of an HTTP request, and they can be set up to fulfill a variety of functions and needs.

V. Processing response

Processing HTTP responses is one of the key parts of using the Requests library. After sending an HTTP request, the server will return a response containing information such as status code, response header and response body. In this section, we will discuss how to handle HTTP responses, including getting the status code, response header and response body, and give examples accordingly.

1. Obtaining status codes

A status code is a numeric encoding of the server's response to a request that indicates the success or failure of the request and the reason for the failure. You can specify the status code by using thestatus_codeproperty to get the status code of the response. The following is an example:

import requests
# Send GET request
response = ('/data')
# Get status code
status_code = response.status_code
# Print status code
print("Status code:", status_code)

The above code sends a GET request and gets the status code of the response. You can use the status code to determine if the request was successful and how to further process the response.

2. Obtaining response headers

The response header contains some meta information about the response, such as the server type, content type, content length, and so on. You can find this information in the response header by using theheadersattribute to get the response header. The following is an example:

import requests
# Send GET request
response = ('/data')
# Get response headers
headers = 
# Print response headers
print("Response header:", headers)

The above code sends a GET request and gets the header information of the response. You can get various useful information from it like content type, server type etc.

3. Obtaining a response body

The response body contains the actual data content returned by the server. You can specify the response body with thetextattribute to get the text content of the response body, or use thecontentproperty to get the binary content. The following is an example:

import requests
# Send GET request
response = ('/data')
# Get the text content of the response body
body_text = 
# Get the binary content of the response body
body_binary = 
# Print the response body text content
print("Response body text content:", body_text)
# Print the binary content of the response body
print("Response body binary content:", body_binary)

The above code sends a GET request and gets the text content and binary content of the response. You can choose to use the text content or binary content of the response body according to your actual needs.

VI. Handling the content of the response

When using the Requests library, we often need to handle different types of response content, including JSON, text and binary. In this section, we will show how to use the Requests library to handle these different types of response content, and give the corresponding examples.

1. Processing JSON response content

If the server returns data in JSON format, we can use thejson()method parses the response into a Python dictionary. Here is an example:

import requests
# Send GET request
response = ('/data')
# Parsing JSON response content
json_data = ()
# Print the parsed data
print("Parsed JSON data:", json_data)

The code above sends a GET request and parses the response into a Python dictionary. You could just use thejson_datavariable to access and manipulate the parsed JSON data.

2. Processing the content of text responses

If the server returns data in text format, we can use thetextproperty to get a textual representation of the response content. The following is an example:

import requests
# Send GET request
response = ('/text')
# Get the content of the text response
text_data = 
# Print text content
print("Text content:", text_data)

The code above sends a GET request and gets a textual representation of the response content. You could just use thetext_datavariable to access and manipulate the text content.

3. Processing of binary response content

Sometimes the server returns data in binary format, such as images, audio, etc. We can use thecontentproperty to get a binary representation of the response content. The following is an example:

import requests
# Send GET request
response = ('/image')
# Get binary response content
binary_data = 
# Write binary content to file
with open('', 'wb') as f:
    (binary_data)

The above code sends a GET request and gets a binary representation of the response content. We then write the binary content to a file namedin the file to save the image file.

VII. Advanced features

The Requests library not only provides basic HTTP request functionality, but also supports many advanced features, including session management, authentication, proxy settings, SSL authentication, and so on. In this section, we will introduce these advanced features and give corresponding examples.

1. Session management

Session management allows you to maintain session state across multiple requests. This is useful for simulating the login process or maintaining a persistent connection. You can use theSessionobject to create a persistent session and send multiple requests within this session. The following is an example:

import requests
# Create session objects
session = ()
# Send the first request
response1 = ('/login')
# Send a second request
response2 = ('/data')
# Close the session
()
# Print the response
print("First request response content:", )
print("Second request response content:", )

The above code creates a session objectsessionThe session object is then used to send two requests. Since these two requests share the same session, the session state can be maintained.

2. Authentication

The Requests library supports a variety of authentication methods, including basic authentication, digest authentication, OAuth authentication, and so on. You can send a request with theauthparameter to specify the authentication method. The following is an example:

import requests
# Basic authentication
response = ('/data', auth=('username', 'password'))
# Print the response
print("Response content:", )

The code above sends a GET request using basic authentication where the user name isusernameThe password ispassword。

3. Proxy settings

Sometimes we need to send HTTP requests through a proxy server, and the Requests library allows you to do that through theproxiesparameter to set the proxy server. The following is an example:

import requests
# Setting up proxy servers
proxies = {
    'http': 'http://10.10.1.10:3128',
    'https': 'https://10.10.1.10:1080',
}
# Send requests through proxy servers
response = ('/data', proxies=proxies)
# Print the response
print("Response content:", )

The code above sets up an HTTP proxy server and an HTTPS proxy server and sends a GET request using these proxy servers.

4. SSL authentication

The Requests library validates SSL certificates for HTTPS requests by default. You can verify the SSL certificate of an HTTPS request with theverifyparameter to control whether SSL authentication is performed. Typically, you can set this toTrueto validate, or set to a string containing the path to the CA certificate file to specify the validation certificate. The following is an example:

import requests
# Send HTTPS request with SSL authentication
response = ('/data', verify=True)
# Print the response
print("Response content:", )

The above code sends an HTTPS request with SSL authentication.

VIII. Exception handling

When making a network request, you may encounter various exceptions, such as network connectivity problems, server errors, timeouts, and so on. To ensure the robustness and reliability of the code, we need to handle these exceptions appropriately. In this section, we will discuss the possible exceptions and show how to handle them using the exception handling mechanism.

1. Network connectivity issues

Network connection problems are one of the most common exceptions. If it is not possible to connect to the target server, the Requests library will throw theConnectionErrorException. You can use thetry-exceptstatement to catch and handle the exception. The following is an example:

import requests
try:
    # Send request
    response = ('/data')
    # Check the response status code
    if response.status_code == 200:
        print("Request successful.")
    else:
        print("Request failed:", response.status_code)
except :
    print("Network connection abnormal, unable to connect to server.")

The code above tries to send a GET request, and if it cannot connect to the server, it will catch theConnectionErrorexception and prints the appropriate error message.

2. Server errors

Sometimes the server may throw an error, such as 500 Internal Server Error. if the server returns an error status code, the Requests library will throw theHTTPErrorException. You can use thetry-exceptstatement to catch and handle the exception. The following is an example:

import requests
try:
    # Send request
    response = ('/data')
    # Check the response status code
    response.raise_for_status()
    print("Request successful.")
except  as err:
    print("Server error:", err)

The above code tries to send a GET request, and if the server returns an error status code, it catches theHTTPErrorexception and prints the appropriate error message.

3. Time-outs

When sending a request, a timeout may occur, where the server does not respond within a specified period of time. If a timeout occurs, the Requests library will throw theTimeoutException. You can use thetry-exceptstatement to catch and handle the exception. The following is an example:

import requests
try:
    # Send the request and set the timeout to 1 second
    response = ('/data', timeout=1)
    print("Request successful.")
except :
    print("Request timed out.")

The above code tries to send a GET request and sets the timeout to 1 second. If a response is not received within the time limit, it captures theTimeoutexception and prints the appropriate error message.

IX. Performance optimization

While the Requests library has provided us with a simple and powerful way to send HTTP requests, there are still some performance optimization techniques that can be used when dealing with large numbers of requests. Here are some suggestions on how to optimize performance using the Requests library:

1. Use of connection pools

By default, a new TCP connection is created each time a request is sent. If you need to send a large number of requests, you can use connection pooling to reuse connections that have already been created to minimize connection creation and closure overhead. You can use theobject to create a session and set connection pooling parameters. The following is an example:

import requests
# Create the session object and set the connection pool size
session = ()
adapter = (pool_connections=100, pool_maxsize=100)
('http://', adapter)
('https://', adapter)
# Send a request using a session object
response = ('/data')
# Close the session
()

The above code creates a session objectsession, and set the connection pool size to 100. by sending requests using the session object, you can reuse established connections and improve performance.

2. Use of persistent connections

Persistent connections allow the client and server to maintain the state of a TCP connection between multiple requests, thereby reducing connection establishment and closure overhead. In HTTP/1.1, persistent connections are enabled by default. You can use theConnection: keep-aliveheader to ensure a persistent connection. Here is an example:

import requests
# Send a request and set the persistent connection header
response = ('/data', headers={'Connection': 'keep-alive'})
# Print the response
print("Response content:", )

The above code sends a GET request with a persistent connection header set. Once the server receives the request, it will maintain the state of the connection and reuse the same connection for subsequent requests, improving performance.

3. Rationalizing the use of concurrency

In some scenarios, you can improve performance by sending multiple requests concurrently. You can use multi-threading, asynchronous requests, etc. to achieve concurrency. However, when using concurrency you need to be careful to control the amount of concurrency wisely to avoid overloading the server. Here's an example of usingExample of a module implementing multi-threaded concurrency:

import requests
import 
# Define the request function
def fetch_data(url):
    response = (url)
    return 
# Define multiple request URLs
urls = ['/data1', '/data2', '/data3']
# Send requests concurrently using multiple threads
with (max_workers=5) as executor:
    results = (fetch_data, urls)
# Print the response
for result in results:
    print("Response content:", result)

The code above defines afetch_datafunction is used to send the request with theThreadPoolExecutorto implement multi-threaded concurrent sending of requests.

X. Cases

The Requests library is widely used in real projects. Below are some practical case studies to show how the Requests library is used in different scenarios.

1. Web crawlers

Web crawlers are a typical scenario where the Requests library is used. By sending an HTTP request, a crawler program can fetch the content of a web page, parse it and extract the information. the Requests library provides a simple but powerful API that makes writing a crawler program easy and efficient. The following is a simple web crawler example for fetching web content:

import requests
# Send a GET request for web content
response = ('')
# Print the content of the web page
print("Page content:", )

In real projects, web crawlers can be used for data collection, search engine indexing and other scenarios.

2. API calls

The Requests library is also widely used to call various Web API interfaces. Many web services provide API interfaces and by sending HTTP requests, we can interact with these services and get data or perform actions. Here is an example of calling GitHub API to get user information:

import requests
# Send a GET request to call the GitHub API
response = ('/users/octocat')
# Parsing JSON response content
user_info = ()
# Print user information
print("Username:", user_info['login'])
print("User ID:", user_info['id'])
print("User URL:", user_info['html_url'])

In real projects, API calls can be used for data acquisition, service integration and other scenarios.

3. Web automation testing

The Requests library can also be used to write web automation test scripts. By sending HTTP requests, we can simulate user interaction with a web application and perform automated tests. Below is an example of using Requests library for web automation testing:

import requests
# Send a POST request to submit form data
response = ('/login', data={'username': 'user', 'password': '123456'})
# Check if login was successful
if 'Welcome, user!' in :
    print("Login successful.")
else:
    print("Login failed.")

Web automation testing can be used to test the functionality and performance of web applications in real projects.

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