Computer Science
Grade 10
20 min
10. Chapter Project: Building an API-Powered Application
Create a Python application that uses an API to retrieve and display data (e.g., a weather app or a news aggregator).
Tutorial Preview
1
Introduction & Learning Objectives
Learning Objectives
Design a simple application plan that utilizes an external API.
Write code to send an HTTP GET request to a specified API endpoint.
Check the status code of an API response to handle successful requests and common errors.
Parse a JSON response to extract specific data fields.
Create objects from API data and store them in a list.
Display the parsed data in a user-friendly format within their application.
Ever wonder how your weather app gets live data or how a music app knows the top trending songs? 🌦️🎶 Let's pull back the curtain and build our own!
In this chapter project, you will combine your programming skills to build a complete application from scratch. You will learn how to request data from a live, external Application Programming Interface...
2
Key Concepts & Vocabulary
TermDefinitionExample
API (Application Programming Interface)A set of rules and protocols that allows different software applications to communicate with each other. It's like a menu at a restaurant: it lists what you can order (request) and what you'll get back (response).The OpenWeatherMap API provides a way for your program to ask its servers for weather data for a specific city.
EndpointA specific URL where an API can be accessed. Different endpoints provide access to different data or functions.In a movie API, `https://api.example.com/movies/search` could be an endpoint for searching movies, while `https://api.example.com/movies/123` could be an endpoint to get details for the movie with ID 123.
HTTP GET RequestA method used to request data from a specified resource, like a...
3
Core Syntax & Patterns
The API Request-Response Cycle
1. Construct URL -> 2. Send Request -> 3. Check Status -> 4. Parse Response -> 5. Use Data
This is the fundamental workflow for any API interaction. You must build the correct URL with the endpoint and any parameters, send the request, verify it was successful (e.g., status 200), convert the JSON text into a usable object, and then access the data within your program.
Accessing JSON Data
Use dictionary-style `['key']` access for objects and list-style `[index]` access for arrays.
JSON data is structured as nested objects (key-value pairs) and arrays (ordered lists). After parsing, you navigate this structure just like you would with native dictionaries and lists in your programming language.
Constructing a URL with Par...
4 more steps in this tutorial
Sign up free to access the complete tutorial with worked examples and practice.
Sign Up Free to ContinueSample Practice Questions
Challenging
You are designing an application to display movie details. The API has an endpoint `/search?title=...` that returns a list of matching movies, and another endpoint `/movie/{id}` that returns detailed information for a specific movie ID. What is the correct sequence of API calls to search for 'Inception' and then display the director of the first search result?
A.Call `/movie/{id}` first to get an ID, then call `/search?title=Inception` with that ID.
B.Call `/search?title=Inception`, parse the response to get the ID of the first movie, then call `/movie/{id}` with that ID.
C.Call `/search?title=Inception` and assume the director's name is in the response, avoiding a second call.
D.Combine the calls into one: `/search?title=Inception&endpoint=/movie/{id}`.
Challenging
An API returns the following nested JSON. To get the 'city' of the first author, what is the correct access chain, and what is a potential pitfall if the 'authors' list is empty? `{"results": [{"title": "Book A", "authors": [{"name": "John Doe", "address": {"city": "New York"}}]}]}`
A.Chain: `data['results'][0]['authors'][0]['address']['city']`. Pitfall: `KeyError` if 'authors' is empty.
B.Chain: `data.results[0].authors[0].address.city`. Pitfall: `AttributeError` if 'authors' is empty.
C.Chain: `data['results'][0]['authors'][0]['address']['city']`. Pitfall: `IndexError` if 'authors' is empty.
D.Chain: `data['results']['authors']['address']['city'][0]`. Pitfall: `TypeError` if 'authors' is empty.
Challenging
You are building an application that uses an external API. Which of the following represents the best application plan, aligning with the tutorial's concepts and objectives?
A.First, build the entire user interface. Then, write a single large function to call the API and parse the data directly into the UI components.
B.First, hardcode sample JSON data into the app to build the UI. Then, replace the hardcoded data with a live API call, ensuring to check the status code and parse the response into a list of objects before displaying.
C.First, write the API call logic. Then, print the raw JSON string to the screen to confirm it works. Finally, build the UI around the raw string.
D.First, find an API. Then, write code to call every single endpoint to see what they do. Finally, pick one and build the UI.
Want to practice and check your answers?
Sign up to access all questions with instant feedback, explanations, and progress tracking.
Start Practicing Free