简单记录一下使用FastAPI完成对数据库的CRUD操作。在参考文档的基础上，增加了U、D部分，全部代码可以参考Github 。
1. Installation
pip install fastapi
pip install uvicorn
pip install sqlalchemy
2. File Structure
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其中：
- crud.py 完成对数据库的CRUD操作
- database.py 关于数据库相关配置
- main.py fastapi路由部分
- models.py 定义表结构
- schemas.py 定义pydantic models信息，也就是schemas
- init.py
3. Details
3.1 database.py
首先需要定义数据库部分，作为demo，使用sqlite作为我们的数据库。这部分都是常规配置操作。
from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
SQLALCHEMY_DATABASE_URL = "sqlite:///./test.db"
engine = create_engine(
SQLALCHEMY_DATABASE_URL, connect_args={"check_same_thread": False}
)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
Base = declarative_base()
3.2 models.py
第二步需要定义我们的表结构，这里定义了User表存储用户数据，item表用于存储物品数据，两者关系是一对多。
from sqlalchemy import Boolean, Column, ForeignKey, Integer, String
from sqlalchemy.orm import relationship
from .database import Base
class User(Base):
__tablename__ = "users"
id = Column(Integer, primary_key=True, index=True)
email = Column(String, unique=True, index=True)
hashed_password = Column(String)
is_active = Column(Boolean, default=True)
items = relationship("Item", back_populates="owner")
def to_dict(self):
return {c.name: getattr(self, c.name) for c in self.__table__.columns}
class Item(Base):
__tablename__ = "items"
id = Column(Integer, primary_key=True, index=True)
title = Column(String, index=True)
description = Column(String, index=True)
owner_id = Column(Integer, ForeignKey("users.id"))
owner = relationship("User", back_populates="items")
def to_dict(self):
return {c.name: getattr(self, c.name) for c in self.__table__.columns}
3.3 schemas.py
第三步需要定义fastapi中schemas信息，后续路由、CRUD时都需要使用。由于增删改查需要不同的schema，所以官网的最佳实践一般都是通过继承解决。
from typing import List
from pydantic import BaseModel
class ItemBase(BaseModel):
title: str
description: str = None
class ItemCreate(ItemBase):
pass
class ItemUpdate(ItemBase):
pass
class Item(ItemBase):
id: int
owner_id: int
class Config:
orm_mode = True
class UserBase(BaseModel):
email: str
class UserCreate(UserBase):
password: str
class UserUpdate(UserBase):
is_active: bool
class User(UserBase):
id: int
is_active: bool
items: List[Item] = []
class Config:
orm_mode = True
3.4 crud.py
接下来就是实际完成CRUD，官网上没有对update、delete做实例展示，这里补充一下。
from sqlalchemy.orm import Session
from . import models, schemas
def get_user(db: Session, user_id: int):
return db.query(models.User).filter(models.User.id == user_id).first()
def get_user_by_email(db: Session, email: str):
return db.query(models.User).filter(models.User.email == email).first()
def get_users(db: Session, skip: int = 0, limit: int = 100):
return db.query(models.User).offset(skip).limit(limit).all()
def create_user(db: Session, user: schemas.UserCreate):
fake_hashed_password = user.password + "notreallyhashed"
db_user = models.User(email=user.email, hashed_password=fake_hashed_password)
db.add(db_user)
db.commit()
db.refresh(db_user)
return db_user
def update_user(db: Session, user_id: int, update_user: schemas.UserUpdate):
db_user = db.query(models.User).filter(models.User.id == user_id).first()
if db_user:
update_dict = update_user.dict(exclude_unset=True)
for k, v in update_dict.items():
setattr(db_user, k, v)
db.commit()
db.flush()
db.refresh(db_user)
return db_user
def delete_user(db: Session, user_id: int):
db_user = db.query(models.User).filter(models.User.id == user_id).first()
if db_user:
db.delete(db_user)
db.commit()
db.flush()
return db_user
def get_items(db: Session, skip: int = 0, limit: int = 100):
return db.query(models.Item).offset(skip).limit(limit).all()
def create_user_item(db: Session, item: schemas.ItemCreate, user_id: int):
db_item = models.Item(**item.dict(), owner_id=user_id)
db.add(db_item)
db.commit()
db.refresh(db_item)
return db_item
def relate_user_item(db: Session, user_id: int, item_id: int):
db_item = db.query(models.Item).filter(models.Item.id == item_id).first()
if db_item:
db_item.owner_id = user_id
db.commit()
db.flush()
return db.query(models.User).filter(models.User.id == user_id).first()
def update_item(db: Session, item_id: int, update_item: schemas.ItemUpdate):
db_item = db.query(models.Item).filter(models.Item.id == item_id).first()
if db_item:
update_dict = update_item.dict(exclude_unset=True)
for k, v in update_dict.items():
setattr(db_item, k, v)
db.commit()
db.flush()
db.refresh(db_item)
return db_item
def delete_item(db: Session, item_id: int):
db_item = db.query(models.Item).filter(models.Item.id == item_id).first()
if db_item:
db.delete(db_item)
db.commit()
db.flush()
return db_item
3.5 main.py
最后完成路由的配置，基本都是按照官网上来的，只是稍微补充了一些删和改的内容，为了让这个demo更加完善。
from typing import List
from fastapi import Depends, FastAPI, HTTPException
from sqlalchemy.orm import Session
from . import crud, models, schemas
from .database import SessionLocal, engine
models.Base.metadata.create_all(bind=engine)
app = FastAPI()
# Dependency
def get_db():
try:
db = SessionLocal()
yield db
finally:
db.close()
@app.post("/users/", response_model=schemas.User)
def create_user(user: schemas.UserCreate, db: Session = Depends(get_db)):
db_user = crud.get_user_by_email(db, email=user.email)
if db_user:
raise HTTPException(status_code=400, detail="Email already registered")
return crud.create_user(db=db, user=user)
@app.get("/users/", response_model=List[schemas.User])
def read_users(skip: int = 0, limit: int = 100, db: Session = Depends(get_db)):
users = crud.get_users(db, skip=skip, limit=limit)
return users
@app.get("/users/{user_id}", response_model=schemas.User)
def read_user(user_id: int, db: Session = Depends(get_db)):
db_user = crud.get_user(db, user_id=user_id)
if db_user is None:
raise HTTPException(status_code=404, detail="User not found")
return db_user
@app.delete('/users/{user_id}', response_model=schemas.User)
def delete_user(user_id: int, db: Session = Depends(get_db)):
db_user = crud.delete_user(db, user_id=user_id)
if db_user is None:
raise HTTPException(status_code=404, detail="User not found")
return db_user
@app.put("/users/{user_id}", response_model=schemas.User)
def update_user(user_id: int, update_user: schemas.UserUpdate, db: Session = Depends(get_db)):
updated_user = crud.update_user(db, user_id, update_user)
if updated_user is None:
raise HTTPException(status_code=404, detail="User not found")
return updated_user
@app.post("/users/{user_id}/items/", response_model=schemas.Item)
def create_item_for_user(
user_id: int, item: schemas.ItemCreate, db: Session = Depends(get_db)
):
return crud.create_user_item(db=db, item=item, user_id=user_id)
@app.get("/items/", response_model=List[schemas.Item])
def read_items(skip: int = 0, limit: int = 100, db: Session = Depends(get_db)):
items = crud.get_items(db, skip=skip, limit=limit)
return items
@app.put("/items/{user_id}/{item_id}/", response_model=schemas.User)
def relate_user_item(user_id: int, item_id: int, db: Session = Depends(get_db)):
user = crud.relate_user_item(db=db, item_id=item_id, user_id=user_id)
return user
@app.put("/items/{item_id}", response_model=schemas.Item)
def update_item(item_id: int, update_item: schemas.ItemUpdate, db: Session = Depends(get_db)):
updated_item = crud.update_item(db, item_id, update_item)
if updated_item is None:
raise HTTPException(status_code=404, detail="Item not found")
return updated_item
@app.delete('/items/{item_id}', response_model=schemas.Item)
def delete_item(item_id: int, db: Session = Depends(get_db)):
db_item = crud.delete_item(db, item_id=item_id)
if db_item is None:
raise HTTPException(status_code=404, detail="User not found")
return db_item
4. Tests
在文件路径下执行，--reload当代码有修改时，可以自动加载。
uvicorn sql_app.main:app --reload
可以通过postman发送请求做测试，这里贴图一张。
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最后fastapi还可以自动生成文档，可以访问http://127.0.0.1:8000/docs查阅。
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