model_validate_json uses dict for property instead of Pydantic model type

[mcantrell]

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• I already checked if it is not related to SQLModel but to SQLAlchemy.

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Example Code

from typing import Optional

from pydantic import BaseModel
from sqlalchemy import JSON
from sqlmodel import SQLModel, Field




class Gadget(BaseModel):
    description: str = Field(description="Description of the gadget")
    
class NormalWidget(BaseModel):
    id: str = Field(description="Widget ID")
    gadget: Optional[Gadget] = Field(description="Gadget associated with the widget")
    
class SqlModelWidget(SQLModel, table=True):
    __tablename__ = "widget"

    id: str = Field(default=None, primary_key=True)
    gadget: Optional[Gadget] = Field(default=None, sa_type=JSON)


JSON_DATA = """
{
  "id": "1",
  "gadget": {
    "description": "A thingy that does stuff"
  }
}
"""

def test_deserialize_data_with_normal_model():
    widget = NormalWidget.model_validate_json(JSON_DATA)
    assert isinstance(widget.gadget, Gadget), "widget.gadget should be of type Gadget"

def test_deserialize_data_with_sql_model():
    widget = SqlModelWidget.model_validate_json(JSON_DATA)    
    assert isinstance(widget.gadget, Gadget), "widget.gadget should be of type Gadget"

Description

In the provided test case, you should see that the normal pydantic model de-serializes the JSON data with the correct type. The SQLModel version uses a dict which is not expected.

Operating System

macOS

Operating System Details

No response

SQLModel Version

0.0.22

Python Version

3.11.9

Additional Context

No response

[mcantrell]

While trying to fix the problem with a custom field_validator, I noticed that my validator wasn't being called. I found #52 (comment) while trying to research related field_validator questions. It seems that adding the validate_assignment config fixes the issue.

class SqlModelWidget(SQLModel, table=True):
    __tablename__ = "widget"

    id: str = Field(default=None, primary_key=True)
    gadget: Optional[Gadget] = Field(default=None, sa_type=JSON)

    class Config:
        validate_assignment = True

Updated test passes:

import json
from typing import Optional, Any

from pydantic import BaseModel, field_validator
from sqlalchemy import JSON
from sqlmodel import SQLModel, Field

from finra.utils import finra_logger


class Gadget(BaseModel):
    description: str = Field(description="Description of the gadget")
    
class NormalWidget(BaseModel):
    id: str = Field(description="Widget ID")
    gadget: Optional[Gadget] = Field(description="Gadget associated with the widget")

class SqlModelWidget(SQLModel, table=True):
    __tablename__ = "widget"

    id: str = Field(default=None, primary_key=True)
    gadget: Optional[Gadget] = Field(default=None, sa_type=JSON)

    class Config:
        validate_assignment = True


JSON_DATA = """
{
  "id": "1",
  "gadget": {
    "description": "A thingy that does stuff"
  }
}
"""

def test_deserialize_data_with_normal_model():
    widget = NormalWidget.model_validate_json(JSON_DATA)
    assert isinstance(widget.gadget, Gadget), "widget.gadget should be of type Gadget"

def test_deserialize_data_with_sql_model():
    widget = SqlModelWidget.model_validate_json(JSON_DATA)    
    assert isinstance(widget.gadget, Gadget), "widget.gadget should be of type Gadget"