SqlModel validate field with another value

Question

I have this sqlmodel:

class User(SQLModel, table=True):
    __tablename__ = "users"
    user_id: Optional[int] = Field(primary_key=True, default=None)
    username: str = Field(unique=True)
    role_id: int = Field(foreign_key='roles.role_id')
    role: Role = Relationship(back_populates="users") 

in the fastapi payload I receive role_description which is a string so I have to find the id associated to that description;

Is it possible to do something like this:

class User(SQLModel, table=True):
    __tablename__ = "users"
    user_id: Optional[int] = Field(primary_key=True, default=None)
    username: str = Field(unique=True)
    role_id: int = Field(foreign_key='roles.role_id')
    role: Role = Relationship(back_populates="users") 

    @validator('role_id')
    def from_role_descr_to_role_id(self, role_descr: str, role:Role):
       return role.role_id

If it is not, how can I avoid making the select query?