I want to explore the creation of a graphql DB using Fastapi and Strawberry. I Start with the basic FastAPI API (taken from their website):
from typing import List, Optional
from fastapi import Depends, FastAPI, HTTPException, Query
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
class TeamBase(SQLModel):
name: str = Field(index=True)
headquarters: str
class Team(TeamBase, table=True):
id: Optional[int] = Field(default=None, primary_key=True)
heroes: List["Hero"] = Relationship(back_populates="team")
class TeamCreate(TeamBase):
pass
class TeamRead(TeamBase):
id: int
class HeroBase(SQLModel):
name: str = Field(index=True)
secret_name: str
age: Optional[int] = Field(default=None, index=True)
team_id: Optional[int] = Field(default=None, foreign_key="team.id")
class Hero(HeroBase, table=True):
id: Optional[int] = Field(default=None, primary_key=True)
team: Optional[Team] = Relationship(back_populates="heroes")
class HeroRead(HeroBase):
id: int
class HeroCreate(HeroBase):
pass
class HeroReadWithTeam(HeroRead):
team: Optional[TeamRead] = None
class TeamReadWithHeroes(TeamRead):
heroes: List[HeroRead] = []
DATABASE_URL = 'postgresql+psycopg2://postgres:password@db:5432/blog_db'
engine = create_engine(DATABASE_URL, echo=True)
def create_db_and_tables():
SQLModel.metadata.create_all(engine)
def get_session():
with Session(engine) as session:
yield session
app = FastAPI()
@app.on_event("startup")
def on_startup():
create_db_and_tables()
@app.post("/heroes/", response_model=HeroRead)
def create_hero(*, session: Session = Depends(get_session), hero: HeroCreate):
db_hero = Hero.from_orm(hero)
session.add(db_hero)
session.commit()
session.refresh(db_hero)
return db_hero
@app.get("/heroes/", response_model=List[HeroReadWithTeam])
def read_heroes(
*,
session: Session = Depends(get_session),
offset: int = 0,
limit: int = Query(default=100, lte=100),
):
heroes = session.exec(select(Hero).offset(offset).limit(limit)).all()
print(heroes)
return heroes
@app.post("/teams/", response_model=TeamRead)
def create_team(*, session: Session = Depends(get_session), team: TeamCreate):
db_team = Team.from_orm(team)
session.add(db_team)
session.commit()
session.refresh(db_team)
return db_team
@app.get("/teams/", response_model=List[TeamRead])
def read_teams(
*,
session: Session = Depends(get_session),
offset: int = 0,
limit: int = Query(default=100, lte=100),
):
teams = session.exec(select(Team).offset(offset).limit(limit)).all()
return teams
I don't fully understand the get method for heroes. In the log, I see it first queries the heroes table and then gets the team information in another query, but after the return. I suppose it's some magic happening thanks to the response_model.
Building a GraphQL sound like an easy task. The problem is that there I cannot make the transformation that takes place thanks to the response_model and it returns only the hero information, without nesting with the team information
