pymongo除了遍历，怎么查到collection.find({})返回的文档条数？

Question

res = collection.find({})

怎么知道返回的res的条数？

Answer 1

import pymongo
client = pymongo.MongoClient(host='localhost', port=27017)
counT = client["databaseName"]["collectionName"].count_documents(filter={})
print(f"num of documents in this collection is {counT}")

输出结果：

num of documents in this collection is 305