Convert all fields to optional #64

First Check

• I added a very descriptive title to this issue.
• I used the GitHub search to find a similar issue and didn't find it.
• I searched the SQLModel documentation, with the integrated search.
• I already searched in Google "How to X in SQLModel" and didn't find any information.
• I already read and followed all the tutorial in the docs and didn't find an answer.
• I already checked if it is not related to SQLModel but to Pydantic.
• I already checked if it is not related to SQLModel but to SQLAlchemy.

Commit to Help

• I commit to help with one of those options 👆

Example Code

class HeroBase(SQLModel):
    name: str
    secret_name: str
    age: Optional[int] = None

class HeroUpdate(HeroBase, all_optional=True):
    pass

Description

Is it possible to add the ability to modify the fields of a base class to convert them to all optional with a parameter like the table=True but in this case all_optional=True? This would help eliminate the duplication when creating a class for making updates.

Wanted Solution

Set all base fields to Optional based on keyword argument.

Wanted Code

class HeroBase(SQLModel):
    name: str
    secret_name: str
    age: Optional[int] = None

class HeroUpdate(HeroBase, all_optional=True):
    pass

Alternatives

No response

Operating System

Linux, Windows

Operating System Details

No response

SQLModel Version

0.0.4

Python Version

3.8.5

Additional Context

No response