Introduction
Python’s aiofiles module enables asynchronous file handling, allowing for non-blocking I/O operations that are essential for writing high-performance asynchronous applications.
Getting Started with aiofiles
To begin using aiofiles, you must first install the package using pip:
pip install aiofiles
Basic Asynchronous File Reading
The following snippet demonstrates how to open and read a file asynchronously:
import aiofiles
import asyncio
async def read_file(file_name):
async with aiofiles.open(file_name, 'r') as f:
contents = await f.read()
print(contents)
asyncio.run(read_file('example.txt'))
Basic Asynchronous File Writing
Writing to a file asynchronously is just as straightforward:
async def write_file(file_name, text):
async with aiofiles.open(file_name, 'w') as f:
await f.write(text)
asyncio.run(write_file('example.txt', 'Hello, aiofiles!'))
Performing Complex Asynchronous File Operations
Beyond basic reading and writing, aiofiles offers capabilities for more complex operations:
Reading Files Line by Line
async def read_lines(file_name):
async with aiofiles.open(file_name, 'r') as f:
async for line in f:
print(line.strip())
asyncio.run(read_lines('example.txt'))
Writing Multiple Lines Asynchronously
async def write_lines(file_name, lines):
async with aiofiles.open(file_name, 'w') as f:
await f.writelines(lines)
lines_to_write = ['First line\n', 'Second line\n', 'Third line']
asyncio.run(write_lines('example.txt', lines_to_write))
Advanced Asynchronous File Handling Techniques
Now let’s explore more advanced techniques for asynchronous file I/O.
Working with Binary Files
aiofiles also supports binary file operations:
async def read_binary_file(file_name):
async with aiofiles.open(file_name, 'rb') as f:
binary_content = await f.read()
async def write_binary_file(file_name, binary_data):
async with aiofiles.open(file_name, 'wb') as f:
await f.write(binary_data)
Using File Context Manager
If you prefer the context manager approach, aiofiles has you covered:
async def file_context_manager(file_name, text):
async with aiofiles.open(file_name, mode='w') as f:
await f.write(text)
Error Handling in Asynchronous File Operations
It’s important to handle possible errors that may occur during asynchronous file I/O:
async def safe_read_file(file_name):
try:
async with aiofiles.open(file_name, 'r') as f:
contents = await f.read()
except FileNotFoundError:
print(f'The file {file_name} was not found.')
except Exception as e:
print(f'An error occurred: {e}')
Combining aiofiles with Other Asynchronous Libraries
aiofiles can efficiently work in conjunction with other asynchronous libraries, like aiohttp for handling HTTP requests and responses.
Downloading and Saving a File Asynchronously
import aiohttp
async def download_and_save(url, file_name):
async with aiohttp.ClientSession() as session:
async with session.get(url) as response:
if response.status == 200:
async with aiofiles.open(file_name, 'wb') as f:
while True:
chunk = await response.content.read(1024)
if not chunk:
break
await f.write(chunk)
See also:
- Python aiohttp: How to Send API Key or User Credentials
- Using aiohttp to send GET requests in Python (2 examples)
- Python aiohttp: How to Manage Log Messages
Conclusion
Asynchronous file I/O with aiofiles in Python simplifies the development of high-performance applications by allowing concurrent I/O operations. This tutorial sought to provide insights into its basic usage, error handling, and integration with other asynchronous tasks, demonstrating its versatility and power.
