Project: Enhance Get Request

📚 Enhancing FastAPI to Return a List of Books

Let’s update our FastAPI application so that it returns a list of books instead of a simple text message.

In this example, we have added six books as sample data.

🗂️ books.py

from fastapi import FastAPI

app = FastAPI()

# Sample data: list of books
BOOKS = [
    {"title": "Title One", "author": "Author One", "category": "science"},
    {"title": "Title Two", "author": "Author Two", "category": "science"},
    {"title": "Title Three", "author": "Author Three", "category": "history"},
    {"title": "Title Four", "author": "Author Four", "category": "math"},
    {"title": "Title Five", "author": "Author Five", "category": "math"},
    {"title": "Title Six", "author": "Author Two", "category": "math"}
]

# Endpoint to get all books
@app.get("/api-endpoint")
def first_api():
    return BOOKS

✅ What changed?

• Added a list called BOOKS containing book details

• The API now returns the entire list instead of a message

• Visiting the endpoint will display all books in JSON format

▶️ Starting the Application

To start the FastAPI application, run one of the following commands in the terminal

uvicorn book:app --reload

🌐 Accessing the Application in the Browser

Once the server is running, follow the URL provided in the terminal or open your default browser manually.

If you access only:

❌ 127.0.0.1:8000

You will see an error. This happens because the root endpoint (/) is not defined.

✅ Accessing the Correct Endpoint

To receive a valid response, navigate to the defined endpoint:

127.0.0.1:8000/api-endpoint

This URL works correctly and returns the expected response. However, viewing raw JSON directly in the browser is not always convenient for testing and exploration

📘 Viewing Your API in Swagger UI

Open the documentation page:

🔗 127.0.0.1:8000/docs

Here, Swagger UI displays all the endpoints available in your application — currently, there is only one. Swagger UI allows you to explore, test, and view responses from your API directly in the browser.

📌 In this example, first_api is a GET request endpoint.

You can click Try it out, then Execute, to call the API without writing any code.

🧪 What You Will See in Swagger UI

After opening the docs page, you will find:

• ▶️ GET /api-endpoint listed as the available endpoint

• 📝 An auto-generated description

• 🔘 Try it out button to enable testing

• 🔗 The request URL

• ▶️ Execute button to send the request

• 📥 Response body showing the books in JSON format

• 📊 Status code (typically 200 OK)

• 🧾 Response headers

Swagger UI makes it easy to test and understand your API while developing.

👀 Use a More Relevant API Endpoint

Update the route to something meaningful, such as /books:

from fastapi import FastAPI

app = FastAPI()

BOOKS = ...

@app.get("/books")
def read_all_books():
    return BOOKS

🔄 No Need to Restart the Server

Since the app is running with auto-reload enabled:

uvicorn books:app --reload

the server automatically restarts whenever you change the code.

📌 The --reload flag watches for file changes and reloads the application for you.

📘 Check the Updated Docs

Now open Swagger UI again:

🔗 127.0.0.1:8000/docs

You will see the updated endpoint GET /books listed there.

📘 Changes You Will See

• ▶️ Endpoint name changes from GET /api-endpoint → GET /books

• 🧠 Function name shown may update to read_all_books

• 🔗 The request URL becomes 127.0.0.1:8000/books

• 📥 Response body still shows the list of books (no change in data)

• 🔘 Try it out and ▶️ Execute buttons remain the same

• 📊 Status code remains 200 OK (on success)

✅ In short: Only the endpoint path changes — everything else works the same.

📝 Summary:

This section demonstrates how to return structured data from FastAPI and use Swagger UI to test and explore API endpoints efficiently.

• Updated the FastAPI app to return a list of books instead of a simple message.

• Created a BOOKS list containing sample book data (title, author, category).

• Modified the endpoint to return the entire list in JSON format.

Key Improvements

• ✅ API now returns structured data (list of dictionaries)

• ✅ Endpoint changed to a more meaningful route (/books)

• ✅ Improved clarity and real-world relevance

Running and Accessing the App

• Start the server using uvicorn books:app --reload

• Accessing 127.0.0.1:8000 returns an error (no root endpoint defined)

• Accessing 127.0.0.1:8000/books returns the list of books

Using Swagger UI

• Open 127.0.0.1:8000/docs

• View available endpoints (e.g., GET /books)

• Use Try it out → Execute to test the API

• See:

  • 📥 JSON response body

  • 📊 Status code (200 OK)

  • 🧾 Response details

Important Note

• The -reload flag enables automatic server restarts when code changes.

• Changing the endpoint path updates the route but does not change the returned data.