Pymongo为某些键指定唯一约束

from pymongo import MongoClient, ASCENDING

# 连接MongoDB数据库
client = MongoClient('mongodb://localhost:27017/')
db = client['mydatabase']
collection = db['mycollection']

# 为某些键指定唯一约束
collection.create_index([('key1', ASCENDING), ('key2', ASCENDING)], unique=True)

# 插入文档
doc1 = {'key1': 'value1', 'key2': 'value2'}
doc2 = {'key1': 'value3', 'key2': 'value4'}
collection.insert_one(doc1)  # 成功插入
collection.insert_one(doc2)  # 抛出DuplicateKeyError异常，因为键(key1, key2)的值在集合中已经存在

# 查询文档
result = collection.find({'key1': 'value1'})
for doc in result:
    print(doc)

# 关闭连接
client.close()