Can a conversion reference other data in the model?

[Ayehavgunne]

Pydantic has this feature where you can set a default_factory that will be provided one argument which is a dict containing all the already validated fields data. You can use this to set the value of a field based on the data of another field. This is helpful in cases where the dataclass/model is frozen.

class User(BaseModel):
    email: EmailStr
    username: str = Field(default_factory=lambda data: data['email'])

I have not been able to find a way to do the same in apischema. Is that possible?