在 Python 中异步写入 CSV 文件

Question

我正在编写具有以下功能的 CSV 文件：

import csv
import os
import aiofiles


async def write_extract_file(output_filename: str, csv_list: list):
    """
    Write the extracted content into the file
    """
    try:
        async with aiofiles.open(output_filename, "w+") as csv_file:
            writer = csv.DictWriter(csv_file, fieldnames=columns.keys())
            writer.writeheader()
            writer.writerows(csv_list)
    except FileNotFoundError:
        print("Output file not present", output_filename)
        print("Current dir: ", os.getcwd())
        raise FileNotFoundError

但是，由于 writerows 方法不允许等待，因此没有行被写入 CSV 文件。
如何解决这个问题？有什么解决方法吗？
谢谢。
可以找到完整代码 here.

Answer 1

在我看来，最好不要尝试将 aiofiles 与 csv 模块一起使用，而运行使用 loop.run_in_executor 的同步代码并像下面这样异步等待它:

def write_extract_file(output_filename: str, csv_list: list):
    """
    Write the extracted content into the file
    """
    try:
        with open(output_filename, "w+") as csv_file:
            writer = csv.DictWriter(csv_file, fieldnames=columns.keys())
            writer.writeheader()
            writer.writerows(csv_list)
    except FileNotFoundError:
        print("Output file not present", output_filename)
        print("Current dir: ", os.getcwd())
        raise FileNotFoundError


async def main():
    loop = asyncio.get_running_loop()
    await loop.run_in_executor(None, write_extract_file, 'test.csv', csv_list)

Answer 2

你可以使用 aiofiles，你只需要将字典转换成一行:)

import aiofiles

async def write_extract_file(
    output_filename: str, csv_list: list
):

    cols = columns.keys()

    async with aiofiles.open(output_filename, mode='w+') as f_out:

        await f_out.write(','.join(cols)+'\n')

        for data in csv_list:

            line = []

            for c in cols:
                line.append(str(data[c]) if c in data else '')

            line = ','.join(line) + '\n'
    
            await f_out.write(line)

Answer 3

您可以使用 aiocsv。以下是将一行异步写入 CSV 文件的快速示例：

import asyncio
import aiofiles
from aiocsv import AsyncWriter

async def main():
    async with aiofiles.open('your-path.csv', 'w') as f:
        writer = AsyncWriter(f)
        await writer.writerow(['name', 'age'])
        await writer.writerow(['John', 25])

asyncio.run(main())

更多示例如下：https://pypi.org/project/aiocsv/

在 Python 中异步写入 CSV 文件

Write a CSV file asynchronously in Python

python

csv

async-await

python-asyncio

fastapi