The Field regex attribute was renamed pattern in pydantic v2

[benoit-arcsec]

First Check

• I added a very descriptive title here.
• I used the GitHub search to find a similar question and didn't find it.
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• 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.

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Example Code

from sqlmodel import Field, SQLModel
from pydantic import Field as PField, constr

class CarV1(SQLModel):
    license_plate: str = Field(regex=r"\w-\w{3}-\w{3}")  # Regex will be silently ignored

class CarV2(SQLModel):
    license_plate: str = Field(pattern=r"\w-\w{3}-\w{3}")  # Should be the new way but no pattern attribute

class CarV3(SQLModel):
    license_plate: str = Field(schema_extra=dict(pattern=r"\w-\w{3}-\w{3}"))  # Works but extra steps

class CarV4(SQLModel):
    license_plate: str = PField(pattern=r"\w-\w{3}-\w{3}")  # Works but we mix two different Field

class CarV5(SQLModel):
    license_plate: constr(pattern=r"\w-\w{3}-\w{3}")  # Works but we mix Field and constr

Description

• Create a SQL model with a str field validated by a regex.
• Use this model as a FastAPI query parameter

The regex is not validated and not documented in openapi.json.

This is caused because Pydantic V2 does not use the regex attribute anymore but the pattern attribute instead: https://docs.pydantic.dev/latest/concepts/fields/#string-constraints

In this case, it could be solved using Field or constr from Pydantic.
Yet, the fact that the regex is ignored is a footgun. And this footgun could be fixed by renaming the attribute to pattern in sqlmodel.main.Field.

Operating System

Linux

Operating System Details

Ubuntu 24.04 (WSL2)

SQLModel Version

0.0.22

Python Version

3.12.3

Additional Context

No response

[benoit-arcsec]

I ended doing even another way. Based on EmailStr from pydantic and this answer: https://stackoverflow.com/a/67871116

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

LicencePlate = Annotated[str, StringConstraints(pattern=r"\w-\w{3}-\w{3}")]

class Car(SQLModel):
    license_plate: LicensePlate

It seems cleaner like this and I can reuse the type.

[YuriiMotov]

Good solution!

As for supporting pattern, let's track it in this discussion: #735

For now you can workaround it by passing it via schema_extra={"pattern": ...}:

from sqlmodel import Field, SQLModel

class CarV1(SQLModel):
    license_plate: str = Field(schema_extra={"pattern": r"\w-\w{3}-\w{3}"})

CarV1(license_plate="A-123-456")  # Valid

try:
    CarV1(license_plate="A-1234-56")  # Invalid
except ValueError as e:
    print(f"Validation error (as expected): {e.errors()[0]['msg']}")
else:
    raise RuntimeError("No validation error, but expected one.")