Question

我正在尝试解析并异步JSON，但得到：

RuntimeWarning：从未等待协程'main'

import os
import pandas as pd
from datetime import datetime, timedelta
from google.cloud import bigquery

script_path = "C:\\Keys\\key.json"
os.environ["GOOGLE_APPLICATION_CREDENTIALS"] = script_path

client = bigquery.Client(project='project_id')
query_job = client.query("SELECT field1, field2, field3 FROM dataset.table ")
df = query_job.to_dataframe()

def to_xml(df, filename=None, mode='w'):
    def row_to_xml(row):
        xml = ['<item>']
        for i, col_name in enumerate(row.index):
            xml.append('  <field name="{0}">{1}</field>'.format(col_name, row.iloc[i]))
        xml.append('</item>')
        return '\n'.join(xml)
    res = '\n'.join(df.apply(row_to_xml, axis=1))

    if filename is None:
        return res
    with open(filename, mode, encoding="utf-8") as f:
        f.write(res)

pd.DataFrame.to_xml = to_xml

df.to_xml('test.xml')

如何正确使用异步？

Answer 1

如错误消息中所述，您必须等待主要功能，因为它是异步的。从the Python3.7 documentation section about coroutines 借来的

请注意，仅调用协程将不会安排其执行

鉴于您要运行顶级入口点，在Python 3.7+中应该使用

if __name__ == "__main__":
    asyncio.run(main())

对于早期版本，您必须自己处理事件循环：

if __name__ == "__main__":
    loop = asyncio.get_event_loop()
    loop.run_until_complete(main())

RuntimeWarning：从未等待协程“ main”

1 个答案: