Lesson 52: Working with JSON

Introduction to JSON

JSON (JavaScript Object Notation) is a lightweight data interchange format. It's commonly used for storing and exchanging data between applications. Python's json module makes it easy to work with JSON data.

JSON is human-readable, language-independent, and perfect for configuration files, APIs, and data storage.

JSON Structure

JSON data looks similar to Python dictionaries and lists:

json_structure.py
# JSON example
json_data = """
{
    "name": "Alice",
    "age": 25,
    "city": "New York",
    "hobbies": ["reading", "coding"]
}
"""

# JSON supports:
# - Objects (dictionaries): {}
# - Arrays (lists): []
# - Strings: "text"
# - Numbers: 123, 45.6
# - Booleans: true, false
# - null: null

Reading JSON

Use json.loads() to parse JSON strings, or json.load() to read from files:

reading_json.py
import json

# Parse JSON string
json_string = '{"name": "Alice", "age": 25}'
data = json.loads(json_string)
print(data["name"])  # Alice
print(data["age"])   # 25

# Read from file
with open("data.json", "r") as file:
    data = json.load(file)
    print(data)

# JSON becomes Python dict/list
print(type(data))  # <class 'dict'>

Writing JSON

Use json.dumps() to convert Python objects to JSON strings, or json.dump() to write to files:

writing_json.py
import json

# Convert Python dict to JSON string
data = {
    "name": "Alice",
    "age": 25,
    "city": "New York"
}

json_string = json.dumps(data)
print(json_string)  # {"name": "Alice", "age": 25, "city": "New York"}

# Pretty print with indentation
pretty_json = json.dumps(data, indent=2)
print(pretty_json)

# Write to file
with open("output.json", "w") as file:
    json.dump(data, file, indent=2)

Common Use Cases

JSON is commonly used for:

API responses and requests
Configuration files
Data storage and exchange
Web applications
Mobile app data

Best Practices

✅ JSON Tips

• Use indent parameter for readable output

• Handle JSON decode errors when reading

• Validate JSON structure before processing

• Use ensure_ascii=False for non-ASCII characters

Working with JSON