Python中使用async/await删除Firestore集合的报错问题咨询

你遇到的报错是因为AsyncCollectionReference调用stream()方法返回的是异步生成器，无法使用普通同步for循环遍历，同时异步环境下的delete()方法也需要用await关键字执行，原同步逻辑的递归调用也要适配异步规则。

Async/Await实现批量删除的思路完全没有问题，只需将原同步代码全量适配异步语法即可，参考实现如下：

async def delete_collection(col_ref, batch_size):
    docs = col_ref.limit(batch_size).stream()
    deleted = 0

    async for doc in docs:
        print(f'Deleting doc {doc.id} => {doc.to_dict()}')
        await doc.reference.delete()
        deleted = deleted + 1

    if deleted >= batch_size:
        return await delete_collection(col_ref, batch_size)

如果要提升删除效率，可以配合异步批量写入AsyncWriteBatch减少IO请求次数，优化后的实现：

from google.cloud.firestore import AsyncWriteBatch

async def delete_collection_batch(col_ref, batch_size):
    deleted = 0
    while True:
        docs = [doc async for doc in col_ref.limit(batch_size).stream()]
        if not docs:
            break
        batch = AsyncWriteBatch(col_ref._client)
        for doc in docs:
            batch.delete(doc.reference)
        await batch.commit()
        deleted += len(docs)
    return deleted

注意：Firestore单次批量操作最多支持500条写入/删除请求，所以设置batch_size时不要超过500的上限。

内容的提问来源于stack exchange，提问作者Keisuke Nagakawa 永川 圭介