Define schema for a model field in sqlmodel without adding another table

Question

I am defining a model for companies using SQLModel the code thus far is as follows:

from typing import Optional
from sqlmodel import SQLModel, Field, JSON
from sqlalchemy import Column
from pydantic import validator

class Company(SQLModel, table=True):
    name:str = Field(index=True, unique=True)
    email:str
    phone:int
    postal_address:dict = Field(default={}, sa_column=Column(JSON))
    shipping_address:Optonal[dict] = Field(default=None, sa_column=Column(JSON))

    @validator('address')
    def validate_address(cls, v):
        fields = ["street_address", "city", "state", "country", "postal_code"]
        for k in v:
            if k not in fields:
                raise ValueError("Please ensure that the address provided has all the necessary fields.")
        return v

What i want to do is define a class Address like this :

class Address(SQLModel or Something Else):
    street_address:str
    city:str
    state:str
    country:str
    postal_code:int

and use this Address class as a field type in my company model like this:

class Company(SQLModel, Table=True):
   # Other Fields
   postal_address:Address
   shpping_address:Optional[Address]

what want to achieve basically is to define a schema for the address field without adding another address table in the database and defining relationships for the company and address tables for the postal and shipping address.

When i inherit from SQLModel in my Address class i get an error saying that there is no matching field type in sqlalchemy.

so far only solution I can think of is using dict as field type and validating it using a validator as mentioned above but I have to use validator to check if the data provided conforms to the schema I want for the address field, can this be achieved in a better way, thanks.

I also can define a request model for address and company separately like this

class AddressRequest(SQLModel):
    street_address:str
    city:str
    state:str
    country:str
    postal_code:int
    
class CompanyRequest(SQLModel):
    name:str = Field(index=True, unique=True)
    email:str
    phone:int
    postal_address:AddressRequest
    shipping_address:AddressRequest
    gst_no:str
    fy_start:date
    fy_end:date

but i get the 422 error in fastapi.