Computer Science
Grade 10
20 min
7. Parsing JSON Data
Learn how to parse JSON data received from an API using Python.
Tutorial Preview
1
Introduction & Learning Objectives
Learning Objectives
Define JSON and explain its role in data exchange with APIs.
Differentiate between JSON objects and JSON arrays, and identify key-value pairs.
Use a programming library (e.g., Python's `json` module) to parse a JSON string into a native data structure.
Access and extract specific data points from simple and nested JSON structures.
Iterate through a JSON array to process multiple data records.
Construct a simple program that fetches data from a mock API and parses the JSON response.
Ever wonder how a weather app on your phone gets the latest forecast instantly, or how your favorite social media feed loads new posts? 🤔 The secret is a universal language for data called JSON!
In this lesson, you'll learn how to read and understand JSON (JavaScrip...
2
Key Concepts & Vocabulary
TermDefinitionExample
JSON (JavaScript Object Notation)A lightweight, text-based format for storing and exchanging data. It's easy for humans to read and write and easy for machines to parse and generate.A simple JSON structure: `{"name": "Alex", "grade": 10, "isActive": true}`
JSON ObjectAn unordered collection of key-value pairs, enclosed in curly braces `{}`. It's similar to a dictionary in Python or a map in other languages.`{"studentId": "S123", "major": "Computer Science"}`
JSON ArrayAn ordered list of values, enclosed in square brackets `[]`. It's similar to a list or array in most programming languages.`["Databases", "OOP", "Algorithms"]`
Key-Value PairThe f...
3
Core Syntax & Patterns
JSON Object Syntax
Objects are enclosed in curly braces `{}`. They contain comma-separated key-value pairs. Keys MUST be strings in double quotes.
Use this structure to represent a single entity with multiple attributes, like a user profile or a book's details.
JSON Array Syntax
Arrays are enclosed in square brackets `[]`. They contain comma-separated values.
Use this structure to represent an ordered list of items, like a list of comments, search results, or student names.
Parsing with a Library
In Python: `import json; data = json.loads(json_string)`
Always use a dedicated JSON library to parse a JSON string. This function reads the string and converts it into a corresponding data structure (e.g., a Python dictionary for a JSON object, a list for a JSON array)...
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Challenging
You have parsed the following JSON into a Python variable `data`:
`{"user": {"name": "Sam", "roles": ["admin", "editor"]}, "status": "active"}`
Which single line of Python code would evaluate to `True`?
A.data['roles'][1] == 'editor'
B.data['user']['roles'] == 'editor'
C.data['user']['roles'][0] == 'editor'
D.'editor' in data['user']['roles']
Challenging
An API returns a JSON array of products, parsed into `products_data`. Each product is an object with a `price` (number) and `inStock` (boolean) key. Which code snippet correctly prints the price of ONLY the products that are in stock?
A.for product in products_data:
if product['inStock']:
print(product['price'])
B.for product in products_data:
if product['price']:
print(product['inStock'])
C.for price in products_data['price']:
if products_data['inStock']:
print(price)
D.if products_data['inStock']:
print(products_data['price'])
Challenging
A JSON string `s = '[{"a": 1, "b": {"c": 2}}, {"a": 3, "b": {"c": 4}}]'` is parsed into a Python object `data`. What is the value of the expression `data[1]['b']['c']`?
A.1
B.2
C.4
D.3
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