[BUG] Pydantic's StringConstraint not working as expected in SQLModel

[mubarakalmehairbi]

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Example Code

from pydantic import BaseModel from sqlmodel import SQLModel, Field from typing_extensions import Annotated from pydantic.types import StringConstraints UsernameStr = Annotated[str, StringConstraints(strip_whitespace=True, to_lower=True)] class NormalModel(BaseModel): username: UsernameStr class SqlModel(SQLModel, table=True): id: str = Field(primary_key=True) username: UsernameStr print(f"Normal: {NormalModel(username='ABC')}") print(f"Sql: {SqlModel(username='ABC')}")

Description

The expected output is:

Normal: username='abc' Sql: username='abc' 

where in both cases the username is in lower case.

However, the output is:

Normal: username='abc' Sql: username='ABC' 

Notice that pydantic converted the username to lower case while sqlmodel didnt.
Note that this only happens if table=True.

Operating System

Windows

Operating System Details

No response

SQLModel Version

0.0.24

Python Version

3.10.0

Additional Context

No response

[YuriiMotov]

This is because of table=True. Such "table"-models bypass validation on instantiation.

You can use SqlModel.model_validate({"username": 'ABC'}) instead of SqlModel(username='ABC').

But conventional approach is to use separate model\models for input and output data validation:

from typing import Optional from pydantic.types import StringConstraints from sqlmodel import Field, SQLModel from typing_extensions import Annotated UsernameStr = Annotated[str, StringConstraints(strip_whitespace=True, to_lower=True)] class SqlModelBase(SQLModel): username: UsernameStr class SqlModelCreate(SqlModelBase): pass class SqlModel(SqlModelBase, table=True): id: Optional[str] = Field(default=None, primary_key=True) a_input = SqlModelCreate(username='ABC') a = SqlModel.model_validate(a_input) print(f"Sql: {a}") # Sql: id=None username='abc'

Read more: #52 (comment)