Python代码如何操作MongoDB Python代码连接NoSQL数据库的实践

from pymongo import MongoClient
from pymongo.errors import ConnectionFailure, OperationFailure

# 连接到MongoDB实例
# 默认连接到 localhost:27017
# 也可以指定主机和端口，比如 client = MongoClient('mongodb://localhost:27017/')
try:
    client = MongoClient('localhost', 27017)
    # 尝试访问一个数据库来验证连接
    client.admin.command('ping')
    print("成功连接到MongoDB!")
except ConnectionFailure as e:
    print(f"连接MongoDB失败: {e}")
    # 在实际应用中，这里可能需要更复杂的错误处理或重试机制
    exit()

# 选择数据库和集合（collection）
db = client.mydatabase # 如果数据库不存在，MongoDB会在第一次插入数据时自动创建
my_collection = db.mycollection # 同样，集合也会自动创建

# --- 插入数据 (Create) ---
# 插入一个文档
post = {"author": "Mike",
        "text": "My first blog post!",
        "tags": ["mongodb", "python", "pymongo"]}
post_id = my_collection.insert_one(post).inserted_id
print(f"插入文档ID: {post_id}")

# 插入多个文档
new_posts = [
    {"author": "John",
     "text": "Another post",
     "tags": ["database", "nosql"]},
    {"author": "Jane",
     "text": "Third post",
     "tags": ["python", "tutorial"]}
]
result = my_collection.insert_many(new_posts)
print(f"插入多个文档ID: {result.inserted_ids}")

# --- 查询数据 (Read) ---
# 查询所有文档
print("\n所有文档:")
for post in my_collection.find():
    print(post)

# 查询一个文档
print("\n查询单个文档 (author: Mike):")
print(my_collection.find_one({"author": "Mike"}))

# 带条件的查询
print("\n查询 tags 包含 'python' 的文档:")
for post in my_collection.find({"tags": "python"}):
    print(post)

# --- 更新数据 (Update) ---
# 更新一个文档
my_collection.update_one({"author": "Mike"}, {"$set": {"text": "Updated first post!"}})
print("\n更新后的 Mike 的文档:")
print(my_collection.find_one({"author": "Mike"}))

# 更新多个文档
# 比如给所有文档添加一个字段
my_collection.update_many({}, {"$set": {"status": "published"}})
print("\n更新所有文档，添加 status 字段:")
for post in my_collection.find():
    print(post)

# --- 删除数据 (Delete) ---
# 删除一个文档
my_collection.delete_one({"author": "John"})
print("\n删除 John 的文档后:")
for post in my_collection.find():
    print(post)

# 删除多个文档
# my_collection.delete_many({"status": "published"}) # 慎用，会删除所有匹配项

# --- 关闭连接 ---
client.close()
print("\nMongoDB连接已关闭。")

from pymongo import MongoClient

# 配置连接池参数
client = MongoClient('mongodb://localhost:27017/',
                     maxPoolSize=50,       # 最大连接数50
                     minPoolSize=5,        # 最小连接数5
                     maxIdleTimeMS=300000) # 连接空闲5分钟后关闭

db = client.another_db
# 之后的所有操作都会使用这个配置的连接池
# ...

from pymongo import MongoClient
from pymongo.errors import ConnectionFailure, OperationFailure, DuplicateKeyError

client = MongoClient('localhost', 27017)
db = client.test_db
my_collection = db.test_collection

try:
    # 尝试插入一个文档
    # 假设 'name' 字段有一个唯一索引
    my_collection.insert_one({"name": "Alice", "age": 30