52 lines
1.7 KiB
Python
52 lines
1.7 KiB
Python
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# database.py
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# 本文件负责配置数据库连接、创建引擎、会话工厂，并提供依赖注入函数。
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#
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# 相比原版的三点改动：
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# 1. 连接串不再硬编码 root/123456，改为读 settings（环境变量 / .env）；
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# 2. 引擎补上 pool_pre_ping / pool_recycle —— 解决 MySQL "server has gone away"；
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# 3. expire_on_commit=False —— 避免 commit 后返回 ORM 对象时又触发隐藏查询。
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import logging
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from sqlalchemy import create_engine
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from sqlalchemy.orm import sessionmaker
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from sqlalchemy.orm.decl_api import declarative_base
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from settings import settings
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logger = logging.getLogger(__name__)
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# 1. 数据库引擎
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engine = create_engine(
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settings.database_url,
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echo=settings.DB_ECHO, # 打开后会把每条 SQL 打到日志，排查问题用
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pool_size=settings.DB_POOL_SIZE, # 连接池常驻连接数
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max_overflow=settings.DB_MAX_OVERFLOW,
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pool_recycle=settings.DB_POOL_RECYCLE, # 超过 N 秒的连接主动回收，避免被 MySQL 断开
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pool_pre_ping=True, # 取连接前先 ping 一次，自动剔除死连接
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future=True,
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)
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# 2. 会话工厂
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# autocommit=False：不自动提交，事务边界由 DAO 显式控制
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# expire_on_commit=False：commit 后对象不过期，API 层序列化时不会再多打一次 SELECT
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SessionLocal = sessionmaker(
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autocommit=False,
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autoflush=False,
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expire_on_commit=False,
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bind=engine,
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)
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# 3. 声明式基类
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Base = declarative_base()
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# 4. 依赖注入：每个 HTTP 请求一个独立会话，请求结束必定关闭
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def get_db():
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db = SessionLocal()
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try:
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yield db
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finally:
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db.close()
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