python中mongodb怎么查询指定字段值是否存在？

import pymongo

 # 链接数据库

client = pymongo.MongoClient(host='127.0.0.1', port=27017)

# 数据库登录需要帐号密码的话

client.runoob.authenticate('runoob', 'runoob',mechanism='SCRAM-SHA-1')

db = client['runoob']  # 获得数据库的句柄

coll = db['details']  # 获得collection的句柄

# python中mongodb判断某字段的值是否存在

count  = coll.count_documents({ "articleid": "d5a603693d943e77be0c9901a92cce28" })

if count !=0:

    print("有")