python 使用 mongodb 的一些方法

1. 安装 pymongo

首先，确保你已经安装了 pymongo 库：

pip install pymongo

2. 连接 MongoDB

创建一个简单的脚本来连接到 MongoDB：

from pymongo import MongoClient

client = MongoClient('mongodb://localhost:27017/')
db = client['example_db']
collection = db['users']

3. 插入数据

插入单个文档

user = {"name": "Alice", "age": 30, "city": "New York"}
result = collection.insert_one(user)
print("Inserted document with id:", result.inserted_id)

插入多个文档

users = [
    {"name": "Bob", "age": 25, "city": "San Francisco"},
    {"name": "Charlie", "age": 35, "city": "Los Angeles"}
]
result = collection.insert_many(users)
print("Inserted documents with ids:", result.inserted_ids)

4. 查询数据

查询单个文档

user = collection.find_one({"name": "Alice"})
print("Found user:", user)

查询多个文档

results = collection.find({"city": "New York"})
for user in results:
    print("User:", user)

5. 更新数据

更新单个文档

new_values = {"$set": {"age": 31}}
result = collection.update_one({"name": "Alice"}, new_values)
print("Modified documents count:", result.modified_count)

更新多个文档

new_values = {"$set": {"city": "New York"}}
result = collection.update_many({"city": "Los Angeles"}, new_values)
print("Modified documents count:", result.modified_count)

6. 删除数据

删除单个文档

result = collection.delete_one({"name": "Alice"})
print("Deleted documents count:", result.deleted_count)

删除多个文档

result = collection.delete_many({"city": "New York"})
print("Deleted documents count:", result.deleted_count)

7. 使用聚合管道

计算每个城市的用户数

pipeline = [
    {"$group": {"_id": "$city", "count": {"$sum": 1}}}
]
results = collection.aggregate(pipeline)
for doc in results:
    print("City:", doc["_id"], "Count:", doc["count"])