之前我们分享的是基于单个表的数据库表的操作,我们在设计数据库的时候也设计了跨表,我们可以看下数据库的设计
class User(Base):
__tablename__ = "users"
id = Column(Integer, primary_key=True, index=True)
email = Column(String(10), unique=True, index=True)
hashed_password = Column(String(100))
is_active = Column(Boolean, default=True)
items = relationship("Item", back_populates="owner")
class Item(Base):
__tablename__ = "items"
id = Column(Integer, primary_key=True, index=True)
title = Column(String(10), index=True)
description = Column(String(10), index=True)
owner_id = Column(Integer, ForeignKey("users.id"))
owner = relationship("User", back_populates="items")
接下来我们就直接看完整的代码
from typing import Optional, List
"""
数据库多表操作
"""
from sqlalchemy import create_engine, ForeignKey
from sqlalchemy.orm import declarative_base
from sqlalchemy.orm import sessionmaker, relationship
from sqlalchemy import Column, Integer, String, Boolean
conn = "mysql+pymysql://{username}:{password}@{host}:{port}/{database}?charset=utf8".format(
username="root", password="123456", host="10.30.10.36", port=3306, database="fastapi_learn_road")
engine = create_engine(conn)
# 该类的每个实例都是一个数据库会话,该类本身还不是数据库会话,但是一旦我们创建了SessionLocal的实例,这个实例将是实际的数据库会话
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
# 创建数据库基类
Base = declarative_base()
# 创建两个数据库模型,继承自Base基类
class User(Base):
__tablename__ = "users"
id = Column(Integer, primary_key=True, index=True)
email = Column(String(10), unique=True, index=True)
hashed_password = Column(String(100))
is_active = Column(Boolean, default=True)
items = relationship("Item", back_populates="owner")
class Item(Base):
__tablename__ = "items"
id = Column(Integer, primary_key=True, index=True)
title = Column(String(10), index=True)
description = Column(String(10), index=True)
owner_id = Column(Integer, ForeignKey("users.id"))
owner = relationship("User", back_populates="items")
from pydantic import BaseModel
from sqlalchemy.orm import Session
from fastapi import FastAPI, Depends, HTTPException
def create_db():
"""每个请求处理完毕后关闭当前连接,不同的请求使用不同的链接"""
db = SessionLocal()
try:
yield db
finally:
db.close()
app = FastAPI()
# -------------------------以下是多表操作
class BaseItem(BaseModel):
title: str
description: Optional[str] = None
class ItemModel(BaseItem):
pass
class ItemOut(BaseItem):
id: int
owner_id: int
class Config:
orm_mode = True
@app.post("/items/{uid}", response_model=ItemOut)
def create_item_by_user(uid: int, item: ItemModel, db: Session = Depends(create_db)):
init_item = Item(**item.dict(), owner_id=uid)
db.add(init_item)
db.commit()
db.refresh(init_item)
return init_item
# 分页获取所有的items
@app.get("/items", response_model=List[ItemOut])
def get_items(skip: int = 0, limit: int = 10, db: Session = Depends(create_db)):
return db.query(Item).offset(skip).limit(limit).all()
# 如何查询用户的items
@app.get("/items/{uid}", response_model=List[ItemOut])
def get_items_by_uid(uid: int, db: Session = Depends(create_db)):
user = db.query(User).filter(User.id==uid).first()
if not user:
raise HTTPException(status_code=200, detail="this user is not valid")
return db.query(Item).filter(Item.owner==user).offset(0).limit(2).all()
postman请求创建item
查询所有的items
查询指定用户的items
我们已经实现了简单的多表查询。