How does Pydantic v2 improve data validation in FastAPI compared to v1?

from pydantic import BaseModel, computed_field, ConfigDict
from typing import Literal

class User(BaseModel):
    model_config = ConfigDict(from_attributes=True)
    id: int
    name: str
    role: Literal["admin", "user"]
    
    @computed_field
    @property
    def display_name(self) -> str:
        return f"{self.name} ({self.role})"

# Usage: auto-validates & computes fields
user = User(id=1, name="Alice", role="admin")
print(user.display_name)  # Alice (admin)