SQLModel fails to create DB constraints when using Annotated types after Pydantic 2.12.0

[MarishLakshmanan]

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Example Code

Environment:
Pydantic==2.12.0

Code:
from pydantic import StringConstraints
NonEmptyString = Annotated[str, StringConstraints(strip_whitespace=True, min_length=1)]

Class Test(SQLModel):
    id: NonEmptyString = Field(primary_key=True) # this was working fine on pydantic v2.11.9

Description

Description

After upgrading to Pydantic 2.12.0, SQLModel no longer creates database constraints (like primary keys, unqiue keys ) for fields defined using Annotated types.

Example:

from typing import Annotated
from sqlmodel import SQLModel, Field
from pydantic import StringConstraints

NonEmptyString = Annotated[str, StringConstraints()]

class Test(SQLModel, table=True):
    id: NonEmptyString = Field(primary_key=True)

Expected Behavior

The table should be created with id as an varchar and primary key

Actual Behavior

it throws an error

sqlalchemy.exc.ArgumentError: Mapper Mapper[Test(test)] could not assemble any primary key columns for mapped table 'test'

Additional notes

In case you use an unique key constraint the table will be created, you will not get any error but the unique key constraint will not be created.

Operating System

Linux

Operating System Details

No response

SQLModel Version

0.0.26

Python Version

3.13.3

Additional Context

No response

[YuriiMotov]

Similar: #1596

[pstanisl]

Similar issues for:

Pydantic dicriminator:

  File "C:\Users\evkas\repo\backend-api\.venv\Lib\site-packages\sqlmodel\main.py", line 714, in get_column_from_field
    sa_type = get_sqlalchemy_type(field)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\evkas\repo\backend-api\.venv\Lib\site-packages\sqlmodel\main.py", line 658, in get_sqlalchemy_type
    type_ = get_sa_type_from_field(field)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\evkas\repo\backend-api\.venv\Lib\site-packages\sqlmodel\_compat.py", line 229, in get_sa_type_from_field
    return get_sa_type_from_type_annotation(type_)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\evkas\repo\backend-api\.venv\Lib\site-packages\sqlmodel\_compat.py", line 214, in get_sa_type_from_type_annotation
    raise ValueError(
ValueError: Cannot have a (non-optional) union as a SQLAlchemy field
make: *** [Makefile:242: prestart] Error 1

And Python list

File "C:\Users\evkas\repo\backend-api\.venv\Lib\site-packages\sqlmodel\main.py", line 565, in __new__
    col = get_column_from_field(v)
          ^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\evkas\repo\backend-api\.venv\Lib\site-packages\sqlmodel\main.py", line 714, in get_column_from_field
    sa_type = get_sqlalchemy_type(field)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\evkas\repo\backend-api\.venv\Lib\site-packages\sqlmodel\main.py", line 703, in get_sqlalchemy_type
    raise ValueError(f"{type_} has no matching SQLAlchemy type")
ValueError: <class 'list'> has no matching

[vimota]

Added a fix in this PR: https://github.com/fastapi/sqlmodel/pull/1607/files

[vimota]

cc @YuriiMotov

[MarishLakshmanan]

Yeah, that fixes my issue. Thanks!!! @vimota

[nielsreijers]

I'm not sure if I should open a new issue for my problem or not, but it's very related to what's being discussed here.

This minimal example:

import sqlmodel

class Event(sqlmodel.SQLModel, table=True):
    id: int = sqlmodel.Field(default=None, primary_key=True)
    event_data: dict = sqlmodel.Field(default_factory=dict, sa_type=sqlmodel.JSON)


class StartEvent(Event, table=False):
    pass

fails with ValueError: <class 'dict'> has no matching SQLAlchemy type because Pydantic replaces the SQLModel FieldInfo with it's own, thus losing the sa_type property.

I've manually applied the fixes in these PRs (including the one mentioned above), but none of them seem to fix the problem.
#1577
#1603
#1607

Are we doing something wrong here? The example here doesn't make much sense, but the original code was one of several experiments with polymorphic_on and polymorphic_identity to get specific class instances for a much larger number of events.

[YuriiMotov]

It's said in the docs:

Only inherit from data models, don't inherit from table models.

Source: https://sqlmodel.tiangolo.com/tutorial/fastapi/multiple-models/#only-inherit-from-data-models

So, according to the docs, it's supposed to be done the following way:

import sqlmodel

class BaseEvent(sqlmodel.SQLModel):
    id: int = sqlmodel.Field(default=None, primary_key=True)
    event_data: dict = sqlmodel.Field(default_factory=dict, sa_type=sqlmodel.JSON)

class Event(BaseEvent, table=True):
    pass

class StartEvent(BaseEvent):
    pass

[sneakers-the-rat]

There seems to be new additional breakage, but there have been longstanding problems with how sqlmodel deals with annotated types and FieldInfo - e.g. for as long as i've used it, if you have any functional validators in the annotated type, the Field will be ignored entirely (whether it was replaced with pydantic's version or not).