FastAPI+SQLAlchemy数据库连接

配置数据库连接

# db.py
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

DATABASE_URL = "mysql+pymysql://root:7997@localhost/fastapidemo"

engine = create_engine(
    DATABASE_URL,
    pool_size=10,            # 设置连接池大小
    max_overflow=20,         # 设置连接池最大溢出连接数量
    pool_timeout=30,         # 设置连接超时时间
    pool_recycle=1800,       # 设置连接的回收时间
)

SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

创建表模型

from sqlalchemy import Column, Integer, String, ForeignKey, Table
from sqlalchemy.orm import DeclarativeBase, relationship


class Base(DeclarativeBase):
    __abstract__ = True  # 标记为抽象基类，防止直接创建表

    @classmethod
    def get_all(cls, session):
        return session.query(cls).all()


book_press = Table('book_press', Base.metadata,
                   Column('book_id', Integer, ForeignKey('book.id'), primary_key=True),
                   Column('press_id', Integer, ForeignKey('press.id'), primary_key=True))


class Book(Base):
    __tablename__ = 'book'
    id = Column(Integer, primary_key=True, autoincrement=True)
    title = Column(String(15), nullable=False, unique=True)
    author_id = Column(Integer, ForeignKey('author.id'))
    author = relationship('Author', backref='books', cascade='all,delete')
    press = relationship('Press', backref='books', secondary=book_press)


class Author(Base):
    __tablename__ = 'author'
    id = Column(Integer, primary_key=True, autoincrement=True)
    name = Column(String(15), nullable=False, unique=True)
    age = Column(Integer, nullable=False)


class Press(Base):
    __tablename__ = 'press'
    id = Column(Integer, primary_key=True, autoincrement=True)
    name = Column(String(15), nullable=False, unique=True)


if __name__ == '__main__':
    from db import engine

    Base.metadata.create_all(engine)

创建alembic迁移文件

安装+初始化

pip install alembic

alembic init alembic

编辑env.py

# env.py
from logging.config import fileConfig
from sqlalchemy import engine_from_config
from sqlalchemy import pool
from alembic import context

# 导入你的 Base 和模型
from module import Base, Book, Author, Press

config = context.config

# 默认None 替换成你的Base
target_metadata = Base.metadata
# 其他配置...

编辑alembic.ini

# alembic.ini
sqlalchemy.url = mysql+pymysql://root:7997@localhost/fastapidemo

迁移数据库

alembic revision --autogenerate
alembic upgrade head

视图函数查询

# main.py
from fastapi import FastAPI, Request, Depends
from pydantic import BaseModel
from sqlalchemy.orm import Session

from db import SessionLocal
from orm import Author

app = FastAPI()
session = SessionLocal()


def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


class Item(BaseModel):
    pass


@app.get("/api/")
async def root(db: Session = Depends(get_db)):
    # 直接用session查询
    res = db.query(Author).all()
    # 调用模型类的方法查询
    res2 = Author.get_all(db)
    print(res[0].name)
    print(res2[0].name)
    return {f"作者名：{res[0].name},{res2[0].name}"}