Can't Allow Extra Fields in SQLModel using Pydantic's extra="allow" option

[LuckierDodge]

First Check

• I added a very descriptive title here.
• I used the GitHub search to find a similar question 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

# Allowing extra fields works with BaseModel:
from pydantic import BaseModel
class Test(BaseModel, extra="allow"):
  pass
Test()
# Output: Test()
test = Test(a="a")
print(test)
# Output: Test(a='a')
test.a
# Output: 'a'


# Allowing extra fields fails with SQLModel
from sqlmodel import SQLModel
class Test(SQLModel, extra="allow"):
   pass 
test = Test()
print(test)
# Output: Test()
Test(a="a")
# Output: Test()
test.a
# Output:
# Traceback (most recent call last):
#   File "<stdin>", line 1, in <module>
#   File "/workspaces/MADSci/.venv/lib/python3.9/site-packages/pydantic/main.py", line 856, in __getattr__
#     raise AttributeError(f'{type(self).__name__!r} object has no attribute {item!r}')
# AttributeError: 'Test' object has no attribute 'a'

Description

• Creating a dataclass using SQLModel doesn't respect Pydantic's extra="allow" config option
• While I don't expect extra fields to be inserted into the database, they can still be useful prior to insertion for additional validation/processing/determining subtype etc.

Operating System

Linux

Operating System Details

Dev Container running in WSL 2

SQLModel Version

0.0.22

Python Version

Python 3.9.2

Additional Context

For my specific use case, I have a Model with many inheriting Models that I'm pre-validating when I read from a file, and have to query another source before I can do final validation with the appropriate submodel. I'd like to preserve the sub-model specific fields in the interim

[LuckierDodge]

Credit to brechin in the discord for pointing out the correct implementation:

from sqlmodel import SQLModel
from pydantic import ConfigDict

class Test(SQLModel):
    model_config = ConfigDict(extra="allow")

test = Test(a="a")
# Output: Test(a='a')
test.a
# Output: 'a'