遍历数据库中的每个集合-mongodb

Question

我正在尝试对mongodb数据库中的每个集合进行查询。数据库有140个集合，查询是这样的：

import pymongo
client=pymongo.MongoClient("localhost",27017)
db=client.EcoEmp_db

pipeline=[db.D12.aggregate([
{"$unwind":"$_id"},
{"$addFields":{
"bibliographic.link":"$link",
"bibliographic.keywords":"$keywords",
"bibliographic.abstract":"$abstract",
"bibliographic.author":"$author"
}},
{
"$replaceRoot":{"newRoot":"$bibliographic"}
},
{"$out": "D12_p"}
])]

我从pymoongo运行此管道，并且可以正常工作。为了迭代每个集合，我这样做：

import pymongo

if __name__ == '__main__':
    connection = pymongo.MongoClient('localhost', 27017)
    db = connection['EcoEmp_db']
    collection = db.collection_names(include_system_collections=False)
    for collect in collection:
        db.db[collect].aggregate([
        {"$unwind":"$_id"},
        {"$addFields":{
        "bibliographic.link":"$link",
        "bibliographic.keywords":"$keywords",
        "bibliographic.abstract":"$abstract",
        "bibliographic.author":"$author"
        }},
        {
        "$replaceRoot":{"newRoot":"$bibliographic"}
        },
        {"$out": collect+"_p"}
        ])

但是我得到了任何东西，似乎不起作用，知道我该怎么办？