SQLModel and emails

That schemaextra is for API documentation, not for validation. The pattern you've specified is only added to (basically) Swagger.

    email: str = Field(maxlength=50, pattern=r'^[\w\.-]+@[\w\.-]+\.[\w\.]+$')

For email validation specifically, Pydantic provides a dedicated type called EmailStr.

    from pydantic import EmailStr
    ...
    email: EmailStr = Field(max_length=50)

EmailStr ensures that any data assigned to the email field will be validated against a well-tested email regex. If the validation fails, a ValidationError will be raised automatically by FastAPI before the data even touches your database logic.

schemaextra is just for docs, doesn't actually validate anything at runtime.

import re
from sqlmodel import SQLModel, Field
from uuid import UUID, uuid4
from pydantic import validator
class User(SQLModel, table=True):
    tablename = 'users'
    id: UUID = Field(defaultfactory=uuid4, primarykey=True)
    username: str = Field(index=True, maxlength=30)
    email: str = Field(maxlength=50)
    @validator("email")
    def validateemail(cls, v):
        pattern = r'^[\w\.-]+@domain\.com$'
        if not re.match(pattern, v):
            raise ValueError("Email must be from yourdomain.com")
        return v

Should solve your problem!