如何使用 pymongo 将集合转储到 json 文件

Question

我正在尝试将一个集合转储到 .json 文件，但在查看 pymongo 教程后我找不到任何与之相关的东西。

教程link：https://api.mongodb.com/python/current/tutorial.html

Answer 1

只需获取所有文档并将它们保存到文件中，例如：

from bson.json_util import dumps
from pymongo import MongoClient

if __name__ == '__main__':
    client = MongoClient()
    db = client.db_name
    collection = db.collection_name
    cursor = collection.find({})
    with open('collection.json', 'w') as file:
        file.write('[')
        for document in cursor:
            file.write(dumps(document))
            file.write(',')
        file.write(']')

Answer 2

补充@kamilitw 我使用游标的长度来正确制作JSON 文件。我使用 count() 和 if-else:

def writeToJSONFile(collection):
    cursor = collection.find({})
    file = open("collection.json", "w")
    file.write('[')
    qnt_cursor = 0
    for document in cursor:
        qnt_cursor += 1
        num_max = cursor.count()
        if (num_max == 1):
            file.write(json.dumps(document, indent=4, default=json_util.default))
        elif (num_max >= 1 and qnt_cursor <= num_max-1):
            file.write(json.dumps(document, indent=4, default=json_util.default))
            file.write(',')
        elif (qnt_cursor == num_max):
            file.write(json.dumps(document, indent=4, default=json_util.default))
    file.write(']')
    return file

所以JSON文件在and中是正确的，因为以前是这样写的：[{"test": "test"},]，现在是这样写的：[{"test":"test1"},{"test":"test2"}]

Answer 3

这是另一种不在右方括号前保存 , 的方法。还使用 with open 保存一些 space.

filter = {"type": "something"}
type_documents = db['cluster'].find(filter)
type_documents_count = db['cluster'].count_documents(filter)

with open("type_documents.json", "w") as file:
    file.write('[')
    # Start from one as type_documents_count also starts from 1.
    for i, document in enumerate(type_documents, 1):
        file.write(json.dumps(document, default=str))
        if i != type_documents_count:
            file.write(',')
    file.write(']')

如果迭代次数等于文档数（这是它保存的最后一个文档），它基本上不会写逗号。

Answer 4

"""
@Author: Aseem Jain
@profile: https://www.linkedin.com/in/premaseem/

"""
import os
import pymongo

# configure credentials / db name
db_user = os.environ["MONGO_ATLAS_USER"]
db_pass = os.environ["MONGO_ATLAS_PASSWORD"]
db_name = "sample_mflix"

connection_string = f"mongodb+srv://{db_user}:{db_pass}@sharedcluster.lv3wx.mongodb.net/{db_name}?retryWrites=true&w=majority"

client = pymongo.MongoClient(connection_string)
db = client[db_name]

# create database back directory with db_name
os.makedirs(db_name, exist_ok=True)

# list all tables in database
tables = db.list_collection_names()

# dump all tables in db
for table in tables:
    print("exporting data for table", table )
    data = list(db[table].find())
    # write data in json file
    with open(f"{db.name}/{table}.json","w") as writer:
        writer.write(str(data))

exit(0)

Answer 5

已接受的解决方案产生了无效 JSON。它导致在右方括号 ] 之前出现尾随逗号 ,。 JSON 规范不允许尾随逗号。看到这个 answer and this reference.

为了构建公认的解决方案，我使用了以下内容：

from bson.json_util import dumps
from pymongo import MongoClient
import json

if __name__ == '__main__':
    client = MongoClient()
    db = client.db_name
    collection = db.collection_name
    cursor = collection.find({})
    with open('collection.json', 'w') as file:
        json.dump(json.loads(dumps(cursor)), file)

如何使用 pymongo 将集合转储到 json 文件

How to dump a collection to json file using pymongo

python

json

mongodb

pymongo-3.x