No83：Python-Pymongo使用技巧

1、update更新数据

现在集合里有3条数据

import pymongo

mongo_client = pymongo.MongoClient(
        host="192.168.0.112", port=27017, username="admin", password="123456"
)
mongo_db = mongo_client["db1"]
# 读取数据
res = mongo_db.chat.find()
for i in res:
    print(i)

# 输出
# {"_id": ObjectId("5cb0ba3abd99392b1427c25e")}
# {"_id": ObjectId("5cb0bbf9bd993914d8b5d82c"), "name": "jack", "age": 13}
# {"_id": ObjectId("5cb0bbf9bd993914d8b5d82d"), "name": "mike", "age": 33}

更新单条数据

import pymongo

mongo_client = pymongo.MongoClient(
        host="192.168.0.112", port=27017, username="admin", password="123456"
)
mongo_db = mongo_client["db1"]
# 更新数据
res = mongo_db.chat.update_one({"age": 13}, {"$set": {"age": 34}})
# modified_count，返回更新的条数
print(res, res.modified_count)
# 查询是否更新成功
res = mongo_db.chat.find_one({"age": 34})
print(res)

# 返回被更新对象
# <pymongo.results.UpdateResult object at 0x0000000002EDBF08>
# 1代表更新的条数
# 1
# 数据改变，更新成功
# {'_id': ObjectId('5cb0bbf9bd993914d8b5d82c'), 'name': 'jack', 'age': 34}

更新多条数据

import pymongo

mongo_client = pymongo.MongoClient(
        host="192.168.0.112", port=27017, username="admin", password="123456"
)
mongo_db = mongo_client["db1"]
# 更新数据
res = mongo_db.chat.update_many({"age": {"$gte": 0}}, {"$set": {"age": 888}})
print(res, res.modified_count)

# 返回对象
# <pymongo.results.UpdateResult object at 0x0000000002EDBF08>
# 2代表更新2条数据
# 2

2、index索引相关操作

简单总结一下pymongo中与index操作相关一些函数，常用的有：

create_index
drop_index
index_information

最主要的是create_index，可以用它来为mongo的collection建立索引。

以下操作一些简单的例子，代码如下：

import pymongo as pm

client = pm.MongoClient(
        "mongodb://user:password@127.0.0.1:27017",
        ssl=True,
        ssl_ca_certs="/tmp/mongo_local.pem",
)

db = client["my_db"]

collection = db["my_collection"]

# 获得已有索引
print([x for x in dir(collection) if "index" in x])

# 创建索引
collection.create_index([("x", 1)], unique=True, background=True)

# 获得索引帮助
help(collection.create_index)

# 获得索引信息
collection.index_infomation()

# 根据索引说明符删除索引
collection.drop_index([("x", 1)])

# 根据索引名称删除索引
collection.drop_index("idx_x")

# 使用多个字段创建索引
collection.create_index([("x", 1), ("y", 1)])