Nested models in FastAPI - Mini Project: Build & Apply

Nested models

📖 Scenario: You are building a simple API for a bookstore. Each book has a title and an author. The author has a name and an email. You want to organize this data using nested models.

🎯 Goal: Create nested Pydantic models in FastAPI to represent a book and its author. The author model should be nested inside the book model.

📋 What You'll Learn

Create a Pydantic model called Author with fields name (string) and email (string).

Create a Pydantic model called Book with fields title (string) and author (of type Author).

Create a FastAPI app instance called app.

Create a POST endpoint /books/ that accepts a Book model as input.

💡 Why This Matters

🌍 Real World

Nested models help organize complex data structures in APIs, like a book with an author inside it.

💼 Career

Understanding nested models is essential for building clear and maintainable APIs in FastAPI, a popular Python web framework.

1

Create the Author model

Create a Pydantic model called Author with two string fields: name and email.

FastAPI

from fastapi import FastAPI
from pydantic import BaseModel

# Create the Author model here

Need a hint?

Use class Author(BaseModel): and define name and email as string fields.

2

Create the Book model with nested Author

Create a Pydantic model called Book with a string field title and a field author of type Author.

FastAPI

from fastapi import FastAPI
from pydantic import BaseModel

class Author(BaseModel):
    name: str
    email: str

# Create the Book model here

Need a hint?

Define class Book(BaseModel): with title as string and author as type Author.

3

Create the FastAPI app instance

Create a FastAPI app instance called app.

FastAPI

from fastapi import FastAPI
from pydantic import BaseModel

class Author(BaseModel):
    name: str
    email: str

class Book(BaseModel):
    title: str
    author: Author

# Create the FastAPI app instance here

Need a hint?

Write app = FastAPI() to create the app instance.

4

Create POST endpoint to accept Book model

Create a POST endpoint /books/ in app that accepts a Book model as input parameter named book.

FastAPI

from fastapi import FastAPI
from pydantic import BaseModel

class Author(BaseModel):
    name: str
    email: str

class Book(BaseModel):
    title: str
    author: Author

app = FastAPI()

# Create POST endpoint /books/ here

Need a hint?

Use @app.post("/books/") decorator and define an async function create_book with parameter book: Book. Return the book object.