JSON to TOON Conversion: Step-by-Step Tutorial with Examples

Converting JSON to TOON is straightforward once you understand the rules. This tutorial walks you through every step with practical code examples.

TOON Conversion Rules

The conversion follows these simple rules:

1. Replace curly braces with indentation
2. Convert uniform arrays to tabular format
3. Remove unnecessary quotes from strings
4. Replace colons with spaces for object keys

Rule 1: Objects Without Braces

JSON Input

{
  "name": "Product A",
  "price": 29.99,
  "inStock": true,
  "category": "Electronics"
}

TOON Output

name: Product A
price: 29.99
inStock: true
category: Electronics

JavaScript Code

function objectToToon(obj, indent = '') {
  let result = '';
  
  for (const [key, value] of Object.entries(obj)) {
    if (typeof value === 'object' && value !== null && !Array.isArray(value)) {
      // Nested object - add key and recurse with indentation
      result += indent + key + '\n';
      result += objectToToon(value, indent + '  ');
    } else if (Array.isArray(value)) {
      // Handle arrays separately
      result += indent + key + ' ' + arrayToToon(value, indent) + '\n';
    } else {
      // Simple key-value
      result += indent + key + ': ' + formatValue(value) + '\n';
    }
  }
  
  return result;
}

function formatValue(val) {
  if (val === null) return 'null';
  if (typeof val === 'boolean') return val.toString();
  if (typeof val === 'number') return val.toString();
  // Quote strings only if they contain special characters
  if (/[,:\n\r]/.test(val)) return '"' + val + '"';
  return val;
}

// Example
const product = {
  name: "Product A",
  price: 29.99,
  inStock: true,
  category: "Electronics"
};

console.log(objectToToon(product));
// Output:
// name: Product A
// price: 29.99
// inStock: true
// category: Electronics

Rule 2: Tabular Arrays

When all items in an array share the same structure, convert to table format:

JSON Input

{
  "orders": [
    {"orderId": "ORD001", "product": "Laptop", "qty": 1, "price": 999.99},
    {"orderId": "ORD002", "product": "Mouse", "qty": 2, "price": 29.99},
    {"orderId": "ORD003", "product": "Keyboard", "qty": 1, "price": 79.99}
  ]
}

TOON Output

orders [3] {orderId, product, qty, price}
ORD001, Laptop, 1, 999.99
ORD002, Mouse, 2, 29.99
ORD003, Keyboard, 1, 79.99

Python Implementation

def array_to_toon(key, arr):
    """Convert uniform array to TOON tabular format"""
    if not arr or not isinstance(arr[0], dict):
        return key + " [" + str(len(arr)) + "]\n" + "\n".join("- " + str(v) for v in arr)
    
    # Check if uniform (all items have same keys)
    first_keys = set(arr[0].keys())
    is_uniform = all(set(item.keys()) == first_keys for item in arr)
    
    if not is_uniform:
        return key + " [" + str(len(arr)) + "]\n" + "\n".join("- " + str(item) for item in arr)
    
    # Create tabular format
    fields = list(arr[0].keys())
    header = key + " [" + str(len(arr)) + "] {" + ', '.join(fields) + "}"
    
    rows = []
    for item in arr:
        values = [format_value(item[f]) for f in fields]
        rows.append(", ".join(values))
    
    return header + "\n" + "\n".join(rows)

def format_value(val):
    """Format a value for TOON"""
    if val is None:
        return "null"
    if isinstance(val, bool):
        return "true" if val else "false"
    if isinstance(val, (int, float)):
        return str(val)
    # Quote if contains comma or newline
    if "," in str(val) or "\n" in str(val):
        return '"' + str(val) + '"'
    return str(val)

# Example
orders = [
    {"orderId": "ORD001", "product": "Laptop", "qty": 1, "price": 999.99},
    {"orderId": "ORD002", "product": "Mouse", "qty": 2, "price": 29.99},
    {"orderId": "ORD003", "product": "Keyboard", "qty": 1, "price": 79.99}
]

print(array_to_toon("orders", orders))
# Output:
# orders [3] {orderId, product, qty, price}
# ORD001, Laptop, 1, 999.99
# ORD002, Mouse, 2, 29.99
# ORD003, Keyboard, 1, 79.99

Rule 3: Nested Objects

JSON Input

{
  "user": {
    "profile": {
      "name": "Jane Doe",
      "email": "jane@example.com"
    },
    "settings": {
      "theme": "dark",
      "notifications": true
    }
  }
}

TOON Output

user
  profile
    name: Jane Doe
    email: jane@example.com
  settings
    theme: dark
    notifications: true

Common Pitfalls

1. Forgetting array length - Always include [N]
2. Inconsistent indentation - Use consistent 2-space indentation
3. Not quoting special characters - Values with commas need quotes
4. Missing field headers - Tabular arrays require {fields}