Hello everyone, today I want to share a super useful Python library – aiohttp! Do you often need to send network requests in your programs? If the number of requests increases, the program can become incredibly slow? Don’t worry, aiohttp is here to solve this problem! It allows our network requests to fly, significantly improving program performance!
What is Asynchronous Request?
Before discussing aiohttp, we need to understand what an asynchronous request is. Imagine you are at a restaurant ordering food:
- Sync method: After ordering, you just sit there waiting until the food is ready before you can do anything else.
- Async method: After ordering, you can check your phone or chat, and the waiter will notify you when the food is ready.
aiohttp is the tool that helps us implement the second method!
Installation and Basic Usage
We need to install aiohttp:
pip install aiohttp
Let’s look at the simplest example:
import aiohttp
import asyncio
async def fetch_data(url):
async with aiohttp.ClientSession() as session:
async with session.get(url) as response:
return await response.text()
async def main():
url = "https://api.github.com"
result = await fetch_data(url)
print(result)
# Run the asynchronous program
asyncio.run(main())
Tip: Pay attention to the <span>async</span> and <span>await</span> keywords in the code; they are standard for asynchronous programming!
Batch Request Example
Let’s look at a more practical example, requesting multiple URLs at the same time:
import aiohttp
import asyncio
import time
async def fetch_url(session, url):
async with session.get(url) as response:
return await response.text()
async def main():
urls = [
"https://api.github.com",
"https://api.github.com/users",
"https://api.github.com/repos"
]
start_time = time.time()
async with aiohttp.ClientSession() as session:
tasks = [fetch_url(session, url) for url in urls]
results = await asyncio.gather(*tasks)
for url, result in zip(urls, results):
print(f"Received response from {url}")
print(f"Total time taken: {time.time() - start_time:.2f} seconds")
asyncio.run(main())
POST Requests and Custom Request Headers
aiohttp can not only send GET requests, but also POST requests and custom headers are a piece of cake:
async def post_example():
async with aiohttp.ClientSession() as session:
# Send a POST request
data = {'name': 'xxx', 'message': 'Learning Python is so much fun!'}
headers = {'User-Agent': 'Mozilla/5.0'}
async with session.post('https://api.example.com/post',
json=data, # Send JSON data
headers=headers) as response:
result = await response.json()
print(result)
Notes:
- Remember to use
<span>async with</span>to automatically close the session and response. - Use
<span>response.json()</span>for JSON data and<span>response.text()</span>for text data. - Don’t forget to handle possible exceptions!
Error Handling
Let’s see how to handle errors gracefully:
async def safe_fetch(url):
try:
async with aiohttp.ClientSession() as session:
async with session.get(url) as response:
if response.status == 200:
return await response.text()
else:
return f"Error: HTTP {response.status}"
except aiohttp.ClientError as e:
return f"Error: {str(e)}"
except Exception as e:
return f"Unknown error: {str(e)}"
Practical Exercise
Try to complete this small task:
- Write a function to get the response time of multiple websites simultaneously.
- Sort the results by response time and output them.
- Add timeout handling to avoid a request hanging the entire program.
Tip: You can use <span>session.get(url, timeout=aiohttp.ClientTimeout(total=5))</span> to set a timeout!
Summary Points
Today we learned:
- The basic usage of aiohttp and the concept of asynchronous requests.
- How to send GET and POST requests.
- Batch processing of multiple requests.
- Best practices for error handling.
Friends, that’s all for today’s Python learning journey! Remember to code actively, and feel free to ask me any questions in the comments. I wish everyone happy learning and continuous improvement in Python!
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