我试着用nodejs写，最后想到了这个:

db.collection('collectionName').mapReduce(
function() {
    for (var key in this) {
        emit(key, null);
    }
},
function(key, stuff) {
    return null;
}, {
    "out": "allFieldNames"
},
function(err, results) {
    var fields = db.collection('allFieldNames').distinct('_id');
    fields
        .then(function(data) {
            var finalData = {
                "status": "success",
                "fields": data
            };
            res.send(finalData);
            delteCollection(db, 'allFieldNames');
        })
        .catch(function(err) {
            res.send(err);
            delteCollection(db, 'allFieldNames');
        });
 });

读取新创建的集合“allFieldNames”后，删除它。

db.collection("allFieldNames").remove({}, function (err,result) {
     db.close();
     return; 
});

基于@Wolkenarchitekt的回答:https://stackoverflow.com/a/48117846/8808983，我写了一个脚本，可以在db中找到所有键的模式，我认为它可以帮助其他人阅读这个线程:

"""
Python 3
This script get list of patterns and print the collections that contains fields with this patterns.
"""

import argparse

import pymongo
from bson import Code


# initialize mongo connection:
def get_db():
    client = pymongo.MongoClient("172.17.0.2")
    db = client["Data"]
    return db


def get_commandline_options():
    description = "To run use: python db_fields_pattern_finder.py -p <list_of_patterns>"
    parser = argparse.ArgumentParser(description=description)
    parser.add_argument('-p', '--patterns', nargs="+", help='List of patterns to look for in the db.', required=True)
    return parser.parse_args()


def report_matching_fields(relevant_fields_by_collection):
    print("Matches:")

    for collection_name in relevant_fields_by_collection:
        if relevant_fields_by_collection[collection_name]:
            print(f"{collection_name}: {relevant_fields_by_collection[collection_name]}")

    # pprint(relevant_fields_by_collection)


def get_collections_names(db):
    """
    :param pymongo.database.Database db:
    :return list: collections names
    """
    return db.list_collection_names()


def get_keys(db, collection):
    """
    See: https://stackoverflow.com/a/48117846/8808983
    :param db:
    :param collection:
    :return:
    """
    map = Code("function() { for (var key in this) { emit(key, null); } }")
    reduce = Code("function(key, stuff) { return null; }")
    result = db[collection].map_reduce(map, reduce, "myresults")
    return result.distinct('_id')


def get_fields(db, collection_names):
    fields_by_collections = {}
    for collection_name in collection_names:
        fields_by_collections[collection_name] = get_keys(db, collection_name)
    return fields_by_collections


def get_matches_fields(fields_by_collections, patterns):
    relevant_fields_by_collection = {}
    for collection_name in fields_by_collections:
        relevant_fields = [field for field in fields_by_collections[collection_name] if
                           [pattern for pattern in patterns if
                            pattern in field]]
        relevant_fields_by_collection[collection_name] = relevant_fields

    return relevant_fields_by_collection


def main(patterns):
    """
    :param list patterns: List of strings to look for in the db.
    """
    db = get_db()

    collection_names = get_collections_names(db)
    fields_by_collections = get_fields(db, collection_names)
    relevant_fields_by_collection = get_matches_fields(fields_by_collections, patterns)

    report_matching_fields(relevant_fields_by_collection)


if __name__ == '__main__':
    args = get_commandline_options()
    main(args.patterns)

这一行将集合中的所有键提取到一个逗号分隔的排序字符串中:

db.<collection>.find().map((x) => Object.keys(x)).reduce((a, e) => {for (el of e) { if(!a.includes(el)) { a.push(el) }  }; return a}, []).sort((a, b) => a.toLowerCase() > b.toLowerCase()).join(", ")

这个查询的结果通常是这样的:

_class, _id, address, city, companyName, country, emailId, firstName, isAssigned, isLoggedIn, lastLoggedIn, lastName, location, mobile, printName, roleName, route, state, status, token

使用pymongo进行清理和可重用的解决方案:

from pymongo import MongoClient
from bson import Code

def get_keys(db, collection):
    client = MongoClient()
    db = client[db]
    map = Code("function() { for (var key in this) { emit(key, null); } }")
    reduce = Code("function(key, stuff) { return null; }")
    result = db[collection].map_reduce(map, reduce, "myresults")
    return result.distinct('_id')

用法:

get_keys('dbname', 'collection')
>> ['key1', 'key2', ... ]

使用python。返回集合中所有顶级键的集合:

#Using pymongo and connection named 'db'

reduce(
    lambda all_keys, rec_keys: all_keys | set(rec_keys), 
    map(lambda d: d.keys(), db.things.find()), 
    set()
)

我试着用nodejs写，最后想到了这个:

db.collection('collectionName').mapReduce(
function() {
    for (var key in this) {
        emit(key, null);
    }
},
function(key, stuff) {
    return null;
}, {
    "out": "allFieldNames"
},
function(err, results) {
    var fields = db.collection('allFieldNames').distinct('_id');
    fields
        .then(function(data) {
            var finalData = {
                "status": "success",
                "fields": data
            };
            res.send(finalData);
            delteCollection(db, 'allFieldNames');
        })
        .catch(function(err) {
            res.send(err);
            delteCollection(db, 'allFieldNames');
        });
 });

读取新创建的集合“allFieldNames”后，删除它。

db.collection("allFieldNames").remove({}, function (err,result) {
     db.close();
     return; 
});