我想获得MongoDB集合中所有键的名称。

例如,从这个:

db.things.insert( { type : ['dog', 'cat'] } );
db.things.insert( { egg : ['cat'] } );
db.things.insert( { type : [] } );
db.things.insert( { hello : []  } );

我想获得唯一的键:

type, egg, hello

当前回答

沿着@James Cropcho的回答,我找到了下面这个我觉得超级好用的方法。这是一个二进制工具,这正是我正在寻找的: mongoeye。

使用这个工具,大约花了2分钟从命令行导出我的模式。

其他回答

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()
)

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

如果你正在使用mongodb 3.4.4及以上版本,那么你可以使用$objectToArray和$group聚合来使用下面的聚合

db.collection.aggregate([
  { "$project": {
    "data": { "$objectToArray": "$$ROOT" }
  }},
  { "$project": { "data": "$data.k" }},
  { "$unwind": "$data" },
  { "$group": {
    "_id": null,
    "keys": { "$addToSet": "$data" }
  }}
])

下面是工作示例

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)

我有一个更简单的工作…

你能做的是插入数据/文档到你的主集合“东西”,你必须在一个单独的集合中插入属性,让我们说“things_attributes”。

所以每次你插入"things"时,你确实会从"things_attributes"中得到该文档的值与你的新文档键的值进行比较,如果有任何新键存在,则将其追加到该文档中并再次重新插入它。

所以things_attributes只有一个唯一键的文档你可以通过findOne()很容易地得到