How to create a field that does not end up in the table?

[vinodkumars]

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Example Code

from enum import Enum
from typing import Any, Dict, Optional, Tuple
from pydantic import  BaseModel
from sqlmodel import SQLModel
from pydantic.alias_generators import to_camel

class Base(SQLModel,revalidate_instances="always",validate_asssignment=True):
    class Config:
        alias_generator=to_camel
        populate_by_name=True

class TextMessageContent(BaseModel):
    text:str

class MessageContentBase(Base):
    text_content:Optional[TextMessageContent]=None

class MessageContent(MessageContentBase, table=True):
    serialized_data:Optional[str]=None

    def __init__(self, **kwargs: Any) -> None:
        super().__init__(**kwargs)
        if self.serialized_data is not None:
            self.text_content=TextMessageContent.model_validate_json(self.serialized_data)
        elif self.text_content is not None:
            self.serialized_data=self.text_content.model_dump_json()

class MessageContentCreate(MessageContentBase):
    pass

class MessageContentPublic(MessageContentBase):
    pass

Description

I have a field called text_content of type TextMessageContent. I do not want it to end up in the table. Its data is serialized and stored in a different field called serialized_data. But I want it to be available in MessageContentCreate and MessageContentPublic.

Read path:

create=MessageContentCreate(text_content=TextMessageContent(text="data"))
content=MessageContent(text_content=create.text_content)

Write path:

public=MessageContentPublic.model_validate(content)
print(public.text_content)

How can I make it so that text_content does not end up in the database?
I don't think pydantic.PrivateAttr() is an option as it doesn't play well with inheritance and enforces a _ prefix. (Feel free to correct me if I am wrong)

Operating System

macOS

Operating System Details

No response

SQLModel Version

0.0.19

Python Version

3.11.8

Additional Context

No response