Delete Data with FastAPI¶
Let's now add a path operation to delete a hero.
This is quite straightforward. 😁
Delete Path Operation¶
Because we want to delete data, we use an HTTP DELETE operation.
We get a hero_id from the path parameter and verify if it exists, just as we did when reading a single hero or when updating it, possibly raising an error with a 404 response.
And if we actually find a hero, we just delete it with the session.
# Code above omitted 👆
@app.delete("/heroes/{hero_id}")
def delete_hero(hero_id: int):
with Session(engine) as session:
hero = session.get(Hero, hero_id)
if not hero:
raise HTTPException(status_code=404, detail="Hero not found")
session.delete(hero)
session.commit()
return {"ok": True}
👀 Full file preview
from fastapi import FastAPI, HTTPException, Query
from sqlmodel import Field, Session, SQLModel, create_engine, select
class HeroBase(SQLModel):
name: str = Field(index=True)
secret_name: str
age: int | None = Field(default=None, index=True)
class Hero(HeroBase, table=True):
id: int | None = Field(default=None, primary_key=True)
class HeroCreate(HeroBase):
pass
class HeroPublic(HeroBase):
id: int
class HeroUpdate(SQLModel):
name: str | None = None
secret_name: str | None = None
age: int | None = None
sqlite_file_name = "database.db"
sqlite_url = f"sqlite:///{sqlite_file_name}"
connect_args = {"check_same_thread": False}
engine = create_engine(sqlite_url, echo=True, connect_args=connect_args)
def create_db_and_tables():
SQLModel.metadata.create_all(engine)
app = FastAPI()
@app.on_event("startup")
def on_startup():
create_db_and_tables()
@app.post("/heroes/", response_model=HeroPublic)
def create_hero(hero: HeroCreate):
with Session(engine) as session:
db_hero = Hero.model_validate(hero)
session.add(db_hero)
session.commit()
session.refresh(db_hero)
return db_hero
@app.get("/heroes/", response_model=list[HeroPublic])
def read_heroes(offset: int = 0, limit: int = Query(default=100, le=100)):
with Session(engine) as session:
heroes = session.exec(select(Hero).offset(offset).limit(limit)).all()
return heroes
@app.get("/heroes/{hero_id}", response_model=HeroPublic)
def read_hero(hero_id: int):
with Session(engine) as session:
hero = session.get(Hero, hero_id)
if not hero:
raise HTTPException(status_code=404, detail="Hero not found")
return hero
@app.patch("/heroes/{hero_id}", response_model=HeroPublic)
def update_hero(hero_id: int, hero: HeroUpdate):
with Session(engine) as session:
db_hero = session.get(Hero, hero_id)
if not db_hero:
raise HTTPException(status_code=404, detail="Hero not found")
hero_data = hero.model_dump(exclude_unset=True)
for key, value in hero_data.items():
setattr(db_hero, key, value)
session.add(db_hero)
session.commit()
session.refresh(db_hero)
return db_hero
@app.delete("/heroes/{hero_id}")
def delete_hero(hero_id: int):
with Session(engine) as session:
hero = session.get(Hero, hero_id)
if not hero:
raise HTTPException(status_code=404, detail="Hero not found")
session.delete(hero)
session.commit()
return {"ok": True}
🤓 Other versions and variants
from typing import Optional
from fastapi import FastAPI, HTTPException, Query
from sqlmodel import Field, Session, SQLModel, create_engine, select
class HeroBase(SQLModel):
name: str = Field(index=True)
secret_name: str
age: Optional[int] = Field(default=None, index=True)
class Hero(HeroBase, table=True):
id: Optional[int] = Field(default=None, primary_key=True)
class HeroCreate(HeroBase):
pass
class HeroPublic(HeroBase):
id: int
class HeroUpdate(SQLModel):
name: Optional[str] = None
secret_name: Optional[str] = None
age: Optional[int] = None
sqlite_file_name = "database.db"
sqlite_url = f"sqlite:///{sqlite_file_name}"
connect_args = {"check_same_thread": False}
engine = create_engine(sqlite_url, echo=True, connect_args=connect_args)
def create_db_and_tables():
SQLModel.metadata.create_all(engine)
app = FastAPI()
@app.on_event("startup")
def on_startup():
create_db_and_tables()
@app.post("/heroes/", response_model=HeroPublic)
def create_hero(hero: HeroCreate):
with Session(engine) as session:
db_hero = Hero.model_validate(hero)
session.add(db_hero)
session.commit()
session.refresh(db_hero)
return db_hero
@app.get("/heroes/", response_model=list[HeroPublic])
def read_heroes(offset: int = 0, limit: int = Query(default=100, le=100)):
with Session(engine) as session:
heroes = session.exec(select(Hero).offset(offset).limit(limit)).all()
return heroes
@app.get("/heroes/{hero_id}", response_model=HeroPublic)
def read_hero(hero_id: int):
with Session(engine) as session:
hero = session.get(Hero, hero_id)
if not hero:
raise HTTPException(status_code=404, detail="Hero not found")
return hero
@app.patch("/heroes/{hero_id}", response_model=HeroPublic)
def update_hero(hero_id: int, hero: HeroUpdate):
with Session(engine) as session:
db_hero = session.get(Hero, hero_id)
if not db_hero:
raise HTTPException(status_code=404, detail="Hero not found")
hero_data = hero.model_dump(exclude_unset=True)
for key, value in hero_data.items():
setattr(db_hero, key, value)
session.add(db_hero)
session.commit()
session.refresh(db_hero)
return db_hero
@app.delete("/heroes/{hero_id}")
def delete_hero(hero_id: int):
with Session(engine) as session:
hero = session.get(Hero, hero_id)
if not hero:
raise HTTPException(status_code=404, detail="Hero not found")
session.delete(hero)
session.commit()
return {"ok": True}
from typing import List, Optional
from fastapi import FastAPI, HTTPException, Query
from sqlmodel import Field, Session, SQLModel, create_engine, select
class HeroBase(SQLModel):
name: str = Field(index=True)
secret_name: str
age: Optional[int] = Field(default=None, index=True)
class Hero(HeroBase, table=True):
id: Optional[int] = Field(default=None, primary_key=True)
class HeroCreate(HeroBase):
pass
class HeroPublic(HeroBase):
id: int
class HeroUpdate(SQLModel):
name: Optional[str] = None
secret_name: Optional[str] = None
age: Optional[int] = None
sqlite_file_name = "database.db"
sqlite_url = f"sqlite:///{sqlite_file_name}"
connect_args = {"check_same_thread": False}
engine = create_engine(sqlite_url, echo=True, connect_args=connect_args)
def create_db_and_tables():
SQLModel.metadata.create_all(engine)
app = FastAPI()
@app.on_event("startup")
def on_startup():
create_db_and_tables()
@app.post("/heroes/", response_model=HeroPublic)
def create_hero(hero: HeroCreate):
with Session(engine) as session:
db_hero = Hero.model_validate(hero)
session.add(db_hero)
session.commit()
session.refresh(db_hero)
return db_hero
@app.get("/heroes/", response_model=List[HeroPublic])
def read_heroes(offset: int = 0, limit: int = Query(default=100, le=100)):
with Session(engine) as session:
heroes = session.exec(select(Hero).offset(offset).limit(limit)).all()
return heroes
@app.get("/heroes/{hero_id}", response_model=HeroPublic)
def read_hero(hero_id: int):
with Session(engine) as session:
hero = session.get(Hero, hero_id)
if not hero:
raise HTTPException(status_code=404, detail="Hero not found")
return hero
@app.patch("/heroes/{hero_id}", response_model=HeroPublic)
def update_hero(hero_id: int, hero: HeroUpdate):
with Session(engine) as session:
db_hero = session.get(Hero, hero_id)
if not db_hero:
raise HTTPException(status_code=404, detail="Hero not found")
hero_data = hero.model_dump(exclude_unset=True)
for key, value in hero_data.items():
setattr(db_hero, key, value)
session.add(db_hero)
session.commit()
session.refresh(db_hero)
return db_hero
@app.delete("/heroes/{hero_id}")
def delete_hero(hero_id: int):
with Session(engine) as session:
hero = session.get(Hero, hero_id)
if not hero:
raise HTTPException(status_code=404, detail="Hero not found")
session.delete(hero)
session.commit()
return {"ok": True}
After deleting it successfully, we just return a response of:
{
"ok": true
}
Recap¶
That's it, feel free to try it out in the interactive docs UI to delete some heroes. 💥
Using FastAPI to read data and combining it with SQLModel makes it quite straightforward to delete data from the database.