How do you define a Pydantic model and use it in FastAPI?

WHAT IT TESTS: Whether you understand how FastAPI leverages Pydantic BaseModel for automatic request body parsing, type validation, and JSON schema generation. ANSWER OUTLINE: First, import BaseModel from pydantic and define a class with name: str and age: int. Second, declare the model as a parameter in the path operation function with the model as its type annotation. RED FLAG: Reaching for request.json() manually, using standard dicts without validation, or forgetting type hints so FastAPI cannot inject the model.