models/price.py

from pydantic import BaseModel, root_validator


class PricePayload(BaseModel):
    symbol: str
    count_back: int = 365
    symbol_type: str = "stock"

    @root_validator
    def validate_dates(cls, values):
        if values['symbol_type'] not in ["index", "stock"]:
            raise ValueError('type should be index or stock')
        return values