Lesson 4 — Structure

Objects and Nesting

JSON objects can contain other objects and arrays as values, letting you model rich, hierarchical data structures of arbitrary depth.

Nesting Objects

A value in a JSON key-value pair can itself be an object, letting you group related fields together logically — an address inside a person, for example.

JSON — Nested objects 
{
  "name": "Kabelo",
  "address": {
    "street": "12 Main Road",
    "city": "Johannesburg",
    "postalCode": "2000"
  },
  "employer": {
    "name": "Acme Corp",
    "location": {
      "city": "Cape Town",
      "country": "South Africa"
    }
  }
}

Common Mistakes

  • Losing track of matching braces in deeply nested structures, making it hard to see where one object ends and another begins.
  • Flattening data that should logically be nested (e.g. streetAddress, cityName as top-level fields) instead of grouping it into a sub-object.
  • Over-nesting simple data unnecessarily, making the structure harder to navigate than it needs to be.
  • Forgetting a comma between sibling key-value pairs at the same nesting level.

Professional Tip

Use a code editor with bracket-matching or JSON-aware syntax highlighting while working with deeply nested structures — it makes it immediately obvious which closing brace belongs to which opening one.

Your Turn

Model a JSON object for a company that has a name and a nested array of employees, each employee itself having a name and a nested object for their contact details (email and phone).

Mini Quiz

Can a JSON object's value be another JSON object?