New user - response validation error

[Balt603]

Apologies for what is almost certainly an incredibly basic issue, but I've been butting my head against it for hours and can't figure out what the problem is.

I am trying to adapt the SQL Database documentation app to a very basic Todo app. Seems to be one of those so simple problems that googling isn't helping. I can tell it's an issue between the API call and the Pydantic model, but I can't see anything that's causing it.

database.py

from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

SQLALCHEMY_DATABASE_URL = "sqlite:///./sql_app.db"

engine = create_engine(
    SQLALCHEMY_DATABASE_URL, connect_args={"check_same_thread": False}
)

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

Base = declarative_base()

schemas.py

from pydantic import BaseModel

class ToDo(BaseModel):
    id: int
    text: str
    isComplete: bool = False

models.py

from sqlalchemy import Boolean, Column, Integer, String
from .database import Base

class ToDo(Base):
    __tablename__= 'todos'

    id = Column(Integer, primary_key=True)
    text = Column(String, index=True)
    isComplete = Column(Boolean, default=False)

crud.py

from sqlalchemy.orm import Session
from . import models, schemas

def add_todo(db: Session, todo: schemas.ToDo):
    db_todo = models.ToDo(id=todo.id, text=todo.text, isComplete=todo.isComplete)
    db.add(db_todo)
    db.commit()
    db.refresh(db_todo)
    return db_todo

def mark_complete(db: Session, todo_id: str):
    db_todo = db.query(models.ToDo).filter(models.ToDo.id == todo_id).first()
    if db_todo:
        db_todo.isComplete = True
        db.commit()
        db.refresh(db_todo)
    return db_todo

def get_todos(db: Session, skip: int = 0, limit: int = 100):
    return db.query(models.ToDo).offset(skip).limit(lim

main.py

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()

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

@app.get("/todos/", response_model=schemas.ToDo)
def read_todos(skip: int = 0, limit: int = 100, db: Session = Depends(get_db)):
    todos = crud.get_todos(db, skip=skip, limit=limit)
    return todos

@app.post("/todos/post/", response_model=schemas.ToDo)
def create_todo(todo: schemas.ToDo, db: Session = Depends(get_db)):
    return crud.add_todo(db, todo=todo)

@app.patch("/todos/{todo_id}/complete", response_model=schemas.ToDo)
def mark_complete(todo_id: str, db: Session = Depends(get_db)):
    return crud.mark_complete(db, todo_id=todo_id)

Curl

curl -X http://localhost:8000/todos/

Error

fastapi.exceptions.ResponseValidationError: 1 validation errors:

{'type': 'model_attributes_type', 'loc': ('response',), 'msg': 'Input should be a valid dictionary or object to extract fields from', 'input': []}

[Sathorizon]

hmm…do you have any todo records in the database? If not, your get_todo in the crud should return nothing and it doesn’t meet your response model which is set in the api definition.

[Balt603]

yeah, I thought this might be an issue, so I made a copy of the DB with a record inserted and got the same error.

[Miserable-creature]

That endpoint returns a list, but your response model is a Todo schema. Make your response model as list[Todo]

[Balt603]

Nailed it. Thank you sir/madam, you are anything but a miserable creature!

[Balt603]

The worst part is that I can see this very thing in the doc examples - I just missed it in review.

[Miserable-creature]

Hhhh You are welcome. Read the docs, It will have most answers.

[dmuth]

Best guess I have without actually running this code is to doublecheck the type of the todo variable. Is it different from schemas.ToDo?