在 Python 中异步编写 CSV 文件

Question

我正在编写具有以下功能的 CSV 文件：import csvimport osimport aiofilesasync 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，由于不允许等待writerows方法，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。完整的代码可以在这里

Answer 1

在我看来，最好不要尝试与模块aiofiles一起使用csv并运行同步代码loop.run_in_executor并异步等待它，如下所示：

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

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())

Answer 3

你可以使用 aiofiles，你只需要将 dict 转换为一行 :)

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)