pydantic + fastapi 响应模式无法验证

Question

schemas.py

class ExpenseBase(BaseModel):
    Fixed: float
    Variable: float
    Salary: float
    month: int
    year: int

class Expense(ExpenseBase):
    class Config:
        arbitrary_types_allowed = True
        orm_mode = True

class ExpenseSingle(BaseModel):
    __root__: Expense
    class Config:
        arbitrary_types_allowed = True
        orm_mode = True

在我的main.py ：

from fastapi import Depends, FastAPI, HTTPException
from fastapi.middleware.cors import CORSMiddleware

from sqlalchemy.orm import Session

from . import api, models, schemas
from .database import SessionLocal, engine

[...]

@app.get('/expense/{id}/', response_model=schemas.ExpenseSingle)
def read_expense(id: int, db: Session = Depends(get_db)):
   
    if id is None or isinstance(id, int) is not int:
        raise HTTPException(status_code=400, detail="ID is not int")

    expense = api.get_expense_by_id(db, id=id)
    return expense

但是当我尝试获取 API 端点时出现以下错误：

pydantic.error_wrappers.ValidationError: 1 validation error for ExpenseSingle
response
  none is not an allowed value (type=type_error.none.not_allowed)

我试图将schemas.py更改为：

class ExpenseSingle(BaseModel):
    reponse: None
    class Config:
        arbitrary_types_allowed = True
        orm_mode = True

我不明白应该在哪里修复它——看起来我不明白pydantic和fastapi是如何相互关联的……

Answer 1

当我开始使用以下代码处理来自数据库的空 ( None ) 响应时，这个问题就解决了：

if not expense:
        raise HTTPException(status_code=404, detail="No Expenses found")

return expense