Reproducer for SQLModel -> JSON -> SQLModel bug

sqlmodel_bug.py

# Minimal reproducer for bugs and inconsistencies around SQLModel->Json->SQLModel roundtrips
# Basically: For SQLModels with table=True, model_validate_json(jstr) is broken,
# and so is model_validate( json.loads(jstr) ), but in slightly different ways.
#
# model_validate_json(jstr) does not restore non-JSON types properly when used with a table=True SQLModel
# For example, UUIDs remain strings.
#
# model_validate( json.loads(jstr) ) *does* restore those types properly when used directly on
# an SQLModel table=True type, but when that SQLModel is a member of another type it's broken in
# the same way as the former case (e.g. UUIDs remain strings)
# 
# Weirdly, for SQLModels with table=False everything seems to work.

import json
import traceback
import warnings

from uuid import uuid4, UUID

from pydantic import BaseModel
from sqlmodel import SQLModel, Field as SQLField

class InnerModelSQLNoTable(SQLModel, table=False):
    id: UUID = SQLField(default_factory=uuid4, primary_key=True)

class InnerModelSQL(InnerModelSQLNoTable, table=True):
    pass

class OuterModel(BaseModel):
    im: InnerModelSQL

class OuterModelNoTable(BaseModel):
    im: InnerModelSQLNoTable


def repro_impl(obj, use_model_validate_json):
    cls_model = type(obj)
    m = "model_validate_json(j)" if use_model_validate_json else "model_validate(json.loads(j))"
    print(f"\nChecking for {cls_model.__name__}, creating copy from json with {m}")

    j = obj.model_dump_json()
    if use_model_validate_json:
        obj2 = cls_model.model_validate_json(j)
    else:
        obj2 = cls_model.model_validate(json.loads(j))

    im = obj2 if cls_model.__name__.startswith("Inner") else obj2.im
    if isinstance(im.id, UUID):
        print("... ok")
    else:
        print(f"!!! ERROR: InnerModel*.id is not a UUID but {type(im.id)}")

    try:
        obj2.model_dump_json()
    except:
        print("obj2.model_dump_json() failed with")
        traceback.print_exc()

def repro(with_table):
    if with_table:
        print("\n### Testing with an InnerModel derived from SQLModel with table=True")
        im = InnerModelSQL()
        om = OuterModel(im=im)
    else:
        print("\n### Testing with an InnerModel derived from SQLModel with table=False")
        im = InnerModelSQLNoTable()
        om = OuterModelNoTable(im=im)

    repro_impl(im, True)
    repro_impl(om, True)

    repro_impl(im, False)
    repro_impl(om, False)


if __name__ == "__main__":
    #warnings.simplefilter("error") # turn UserWarnings into exceptions
    repro(False)
    repro(True)