Resource expansion (embed related data) in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this REST API call with resource expansion?

Given an API endpoint /orders?expand=customer that returns orders with embedded customer data, what will be the customer name in the first order?

Rest API

{
  "orders": [
    {
      "id": 101,
      "total": 250,
      "customer": {
        "id": 1,
        "name": "Alice Smith"
      }
    },
    {
      "id": 102,
      "total": 150,
      "customer": {
        "id": 2,
        "name": "Bob Jones"
      }
    }
  ]
}

A "null"

B "Bob Jones"

C "Customer data not included"

D "Alice Smith"

💡 Hint

Resource expansion embeds related data inside the main resource.

The expand=customer query parameter includes the full customer object inside each order. The first order's customer name is "Alice Smith".

🧠 Conceptual

intermediate

Why use resource expansion in REST APIs?

What is the main benefit of using resource expansion (embedding related data) in REST API responses?

A It reduces the number of API calls needed to get related data.

B It makes the API response smaller in size.

C It hides related data from the client.

D It forces clients to request related data separately.

💡 Hint

Think about how many requests a client must make to get all needed data.

Embedding related data reduces the number of calls a client must make, improving efficiency and user experience.

🔧 Debug

advanced

Why does this API response fail to include expanded data?

An API call to /products?expand=category returns:

{
  "products": [
    {"id": 10, "name": "Pen", "category": 3}
  ]
}

Why is the category data not embedded?

A The API does not support the <code>expand</code> parameter for categories.

B The client forgot to include <code>expand=category</code> in the request.

C The category field is a number, so expansion is automatic.

D The server returned a syntax error.

💡 Hint

Check if the API supports expansion for the requested field.

If the API does not support expansion for a field, the related data will not be embedded even if requested.

📝 Syntax

advanced

Which query string correctly requests multiple expansions?

You want to expand both author and comments in a REST API call. Which query string is correct?

A /posts?expand=author;comments

B /posts?expand=author&comments

C /posts?expand=author,comments

D /posts?expand=[author,comments]

💡 Hint

Multiple expansions are usually comma-separated in one parameter.

The standard way to request multiple expansions is to list them comma-separated in the expand parameter.

🚀 Application

expert

How many items are in the expanded response list?

An API call to /users?expand=orders returns 3 users. Each user has a different number of orders:

• User 1 has 2 orders
• User 2 has 0 orders
• User 3 has 1 order

How many total order objects are embedded in the response?

A 0

B 3

C 1

D 2

💡 Hint

Add the orders from all users.

The total embedded orders are 2 + 0 + 1 = 3.