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How to operate MongoDB database with Python

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2023-05-28 09:31:102816browse

1. Connector installation and configuration

pymongo: The Python toolkit officially provided by MongoDB. Official documentation: https://pymongo.readthedocs.io/en/stable/ pip installation, the command is as follows: 

pip install pymongo

Main steps to manage MongoDB As follows:

  • Connect to the MongoDB database system

  • Manage the MongoDB database

  • Management Collections in MongoDB

  • Manage documents in MongoDB

The first step is to connect to MongoDB: 

# 方式一: 使用默认的配置
client = MongoClient()
# 方式二: 指定主机地址和端口号
client = MongoClient('localhost', 27017)
# 方式三: 使用URI连接参数
client = MongoClient('mongodb://localhost:27017/')

The second step, manage the database: 

#通过MongoClient对象来管理多个数据库获取数据库(逻辑库)对象
db = client.DATABASE_NAME
db = client["DATABASE_NAME"]
db = client.get_database(name=None, *args)
# 查看所有的数据库(逻辑库)
client.list_databases()
# 删除数据库(逻辑库)
client.drop_database(name_or_database, *args)

The third step, manage the collection

# 通过数据库对象db来管理集合
# 获取集合对象
db = client.DATABASE_NAME
db.COLLECTION_NAME
client.DATABASE_NAME.COLLECTION_NAME
db.get_collection(name, *args)
# 查看当前数据库下的集合列表
db.list_collection_names()
# 删除集合
db.drop_collection(name_or_collection, *args)

Basic operation example:

# -*- coding: utf-8 -*-
# @Time    : 2023-03-17 1:47
# @Author  : AmoXiang
# @File    : 1.数据库连接.py
# @Software: PyCharm
# @Blog    : https://blog.csdn.net/xw1680

from pymongo import MongoClient

# 使用默认配置连接到数据库
# client = MongoClient()
# print(client)
# client.close()
# 指定主机地址和端口号连接到数据库
# client = MongoClient('localhost', 27017)
# 使用URI连接参数连接到数据库
client = MongoClient('mongodb://localhost:27017/')
print(client)
# client.close()
#
# # 访问数据库
# db = client.test
# db = client["test"]
# print(db)
# db = client.get_database('test')
# client.close()
# print(db)
#
# 查看有哪些数据库
db_list = client.list_databases()
# # db_list = client.list_database_names()
for item in db_list:
    print(item)
#
# 查看数据库下有哪些集合
db_test = client["test"]
for item in db_test.list_collection_names():
    print(item)
#
# # 集合对象操作
# data = db_test.students.find_one()
# data = client.test.students.find_one()
data = client.test.get_collection('students').find_one()
print(data)

2. New document

Description: pymongo can convert python objects into BSON when inserting data

insert_one(): Insert a document

# 调用方法
result = db.COLLECTION_NAME.insert_one(doc)
# 返回插入的文档ID
result.inserted _id

insert_many(): Add documents in batches. Calling method: 

doc_list = [doc1,doc2]
result = db.COLLECTION_NAME.insert_many(doc_list)

Example:

3. Query documents

pymongo can convert the query results into objects in python

Common methods: 

find_one(): 按条件查询一个文档
find(): 按条件查询多个文档
count_documents(): 统计满足条件的文档总数
aggregate(): 聚合统计
.sort(): 排序
.skip().limit(): 分页

Sample code: 

# -*- coding: utf-8 -*-
# @Time    : 2023-03-18 15:03
# @Author  : AmoXiang
# @File    : 5.查询文档.py
# @Software: PyCharm
# @Blog    : https://blog.csdn.net/xw1680

from bson.objectid import ObjectId
from pymongo import MongoClient, ASCENDING, DESCENDING


class LearnMongoDBSearch(object):
    """ MongoDB查询练习 """

    def __init__(self):
        self.client = MongoClient()

    def search_one(self):
        """ 查询一个文档 """
        temp_obj = self.client.test.newdb.find_one()
        print(temp_obj)
        print('喜欢分数：', temp_obj['likes'])
        # print('注册时间：', temp_obj['reg_date'].date())
        print('姓名：', temp_obj['uname'])

    def search_user_by_pk(self, pk):
        obj_id = ObjectId(pk)
        # user_obj = self.client.test.newdb.find_one({'_id': obj_id})
        # 面向对象的方法，有代码提示
        db = self.client.get_database('test')
        users = db.get_collection('newdb')
        user_obj = users.find_one({'_id': obj_id})
        print(user_obj)

    def search_many(self):
        """ 查询多个文档 """
        db = self.client.get_database('test')
        students = db.get_collection('students')
        # stu_list = students.find()
        # for item in stu_list:
        #     print(item)

        # 查询年龄大于12岁的学生
        stu_list = students.find({'age': {'$gt': 12}}, {'stu_name': 1, 'class_name': 1, 'age': 1})
        for item in stu_list:
            # 注意:  mongo中存储的整数转换成了浮点数
            print(item)

    def paginate(self, page=1, page_size=10):
        """
        分页处理
        :param page: 当前的页
        :param page_size: 每一页数据大小
        :return:
        """
        db = self.client.get_database('test')
        students = db.get_collection('students')
        offset = (page - 1) * page_size
        stu_list = students.find().skip(offset).limit(page_size)
        return stu_list

    def sort_data(self):
        """ 排序 """
        db = self.client.get_database('test')
        grades = db.get_collection('grades')
        # // 将学生的语文成绩从高到低排序
        # db.grades.find({"grade.course_name": "语文"}).sort({"grade.score": -1});
        #
        # //将学生的语文成绩按照年龄和成绩排序
        # db.grades.find({"grade.course_name": "语文"}).sort({"age": -1, "grade.score": -1});
        # db.grades.find({"grade.course_name": "语文"}).sort({"grade.score": -1, "age": -1});

        # 按某一列排序
        # data_list = grades.find({"grade.course_name": "语文"}).sort("grade.score", DESCENDING);
        # for item in data_list:
        #     print(item)

        # 按多列排序
        data_list = grades.find({"grade.course_name": "语文"}).sort([('age', DESCENDING),("grade.score", DESCENDING),])
        for item in data_list:
            print(item)

    def counter_students(self):
        """ 统计newdb中文档总数 """
        db = self.client.get_database('test')
        newdb = db.get_collection('newdb')
        # result = newdb.count_documents({})
        result = newdb.count_documents({"uname": {"$eq": "张三"}})
        print(result)

    def test_aggregate(self):
        """
        聚合统计：及格的学生成绩
        """
        db = self.client.get_database('test')
        grades = db.get_collection('grades')
        result = grades.aggregate([
            # //where
            {
                '$match': {"grade.score": {'$gte': 60}}
            },
            # //group by
            {
                '$group': {
                    '_id': "$stu_no",
                    'total': {'$sum': 1}
                }
            },
            # // having
            {
                '$match': {
                    'total': {'$eq': 3}
                }
            }
            ])
        for item in result:
            print(item)


if __name__ == '__main__':
    obj = LearnMongoDBSearch()
    # obj.search_one()
    # obj.search_user_by_pk('6411ee77b6170000b4003f95')
    # obj.search_many()
    # stu_list = obj.paginate(page=3)
    # for item in stu_list:
    #     print(item)

    # obj.sort_data()
    # obj.counter_students()
    obj.test_aggregate()

4. Update the document

Review, update the data expression, as shown in the following table:

How to operate MongoDB database with Python

Modify a document and call the method: 

update_one(filter, update, *args)

Replace a document and call the method: 

replace_one(filter, replacement, *args)

Modify documents in batches and call the method: 

replace_one(filter, replacement, *args)

Shortcut method: 

find_one_and_update(filter, update, *args)  # 修改一个文档
find_one_and_replace(filter, replacement, *args)  # 替换一个文档
# 注意返回值的不同

Return results:

acknowledged: whether the result has been confirmed
modified_count: the number of modified documents
matched_count: the number of documents that meet the conditions
raw_result: original data
upserted_id: updated ID (upsert=True)

Sample code: 

# -*- coding: utf-8 -*-
# @Time    : 2023-03-18 14:56
# @Author  : AmoXiang
# @File    : 4.修改文档.py
# @Software: PyCharm
# @Blog    : https://blog.csdn.net/xw1680

from pymongo import MongoClient

class LearnMongoDBUpdate(object):
    """ MongoDB更新练习 """

    def __init__(self):
        self.client = MongoClient()

    def test_update_one(self):
        """ 更新一个文档 """
        db = self.client.get_database('test')
        newdb = db.get_collection('newdb')
        result = newdb.update_one({}, {'$set': {'likes': 70}})
        print(result.modified_count)

    def test_replace_one(self):
        """ 替换一个文档 """
        db = self.client.get_database('test')
        newdb = db.get_collection('newdb')
        result = newdb.replace_one({}, {'uname': '张三'})
        print(result.modified_count)

    def test_update_many(self):
        """ 批量更新文档 """
        db = self.client.get_database('test')
        newdb = db.get_collection('newdb')
        result = newdb.update_many({}, {'$set': {'likes': 90}})
        print('修改的数量：', result.modified_count)
        print('满足条件的数量：', result.matched_count)

    def test_update_shortcut(self):
        """ 更新文档的快捷方法 """
        db = self.client.get_database('test')
        newdb = db.get_collection('newdb')
        # 此处返回一个文档对象
        result = newdb.find_one_and_update({}, {'$set': {'sex': '未知'}})
        print(result['_id'])
if __name__ == '__main__':
    obj = LearnMongoDBUpdate()
    # obj.test_update_one()
    # obj.test_replace_one()
    # obj.test_update_many()
    obj.test_update_shortcut()

5. Delete documents

To delete a document, the calling method is as follows: 

result = db.COLLECTION_NAME.delete_one(filter, *args)
# 返回已经删除的记录数 result.deleted_count
# 删除时返回文档对象 
find_one_and_delete(filter, *args)

To delete documents in batches, the calling method is: 

result = db.COLLECTION_NAME.delete_many(filter, *args)
# 返回已经删除的记录数
result. deleted_count

Example Code: 

# -*- coding: utf-8 -*-
# @Time    : 2023-03-18 14:34
# @Author  : AmoXiang
# @File    : 3.删除文档.py
# @Software: PyCharm
# @Blog    : https://blog.csdn.net/xw1680

from pymongo import MongoClient


class LearnMongoDBDelete(object):
    """ MongoDB删除练习 """

    def __init__(self):
        self.client = MongoClient()

    def test_delete_one(self):
        """ 删除一个文档 """
        db = self.client.get_database('test')
        newdb = db.get_collection('newdb')
        result = newdb.delete_one({})
        print(result.deleted_count)

    def test_delete_many(self):
        """ 批量删除文档 """
        db = self.client.get_database('test')
        users = db.get_collection('newdb')
        # 删除所有的数据
        result = users.delete_many({"likes": {"$lte": 90}})
        print(result.deleted_count)

    def test_delete_shortcut(self):
        """ 删除文档的快捷方法 """
        db = self.client.get_database('test')
        newdb = db.get_collection('newdb')
        result = newdb.find_one_and_delete({})
        print(result['title'])


if __name__ == '__main__':
    obj = LearnMongoDBDelete()
    # obj.test_delete_one()
    # obj.test_delete_shortcut()
    obj.test_delete_many()

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