python - MongoDB:链查找()

Question

在 MongoDB 中，如何链接 find() 方法？假设我想在 Python/pymongo 中做这样的事情

query = prices.find({'symbol': "AAPL"})
if start is not None:
    query = query.find({'date': {'$gte': start}})
if end is not None:
    query = query.find({'date': {'$lte': end}})

Answer 1

您不能链接查找方法。调用 find 将返回 Cursor目的。您可能想要构建一个查询，然后调用 find:

from collections import OrderedDict

query = OrderedDict([('symbol', 'AAPL')])

if start is not None:
    query['date'] = {'$gte': start}
if end is not None:
    query['date'] = {'$lte': end}

cursor = prices.find(query)