Request body structure in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this JSON request body?

Given this JSON request body sent to an API, what is the value of the "totalPrice" field after the server calculates it?

Rest API

{
  "items": [
    {"name": "apple", "quantity": 2, "price": 3},
    {"name": "banana", "quantity": 1, "price": 1}
  ],
  "totalPrice": 0
}

A 7

B 6

C 5

D 0

💡 Hint

Multiply quantity by price for each item and add them up.

The total price is (2 * 3) + (1 * 1) = 6 + 1 = 7.

🧠 Conceptual

intermediate

Which HTTP method usually requires a request body?

Choose the HTTP method that typically sends data in the request body to create or update resources.

A GET

B HEAD

C DELETE

D POST

💡 Hint

Think about sending new data to the server.

POST requests usually include a request body to send data to the server.

🔧 Debug

advanced

What error will this JSON request body cause?

This JSON request body is sent to an API expecting a list of users. What error will the server likely return?

Rest API

{
  "users": {
    "name": "Alice",
    "age": 30
  }
}

A KeyError: 'users' not found

B SyntaxError: Invalid JSON format

C TypeError: Expected a list but got an object

D No error, processed successfully

💡 Hint

The server expects a list but got a single object.

The server expects 'users' to be a list, but the JSON has an object instead, causing a TypeError.

📝 Syntax

advanced

Which JSON request body is syntactically correct?

Select the JSON request body that is valid and can be parsed without errors.

A { user: { name: "Bob", age: 25 } }

B { "user": { "name": "Bob", "age": 25 } }

C { "user": { "name": "Bob", "age": 25, }

D { "user": { "name": "Bob", "age": 25 }, }

💡 Hint

Look for trailing commas and missing quotes.

Option B is valid JSON. Option B has a trailing comma, C is missing a closing brace, D uses unquoted keys.

🚀 Application

expert

How many items are in the 'products' list in this JSON request body?

Count the number of product objects inside the 'products' array in this JSON request body.

Rest API

{
  "products": [
    {"id": 1, "name": "Pen"},
    {"id": 2, "name": "Notebook"},
    {"id": 3, "name": "Eraser"},
    {"id": 4, "name": "Ruler"}
  ]
}

A 4

B 5

C 3

D 2

💡 Hint

Count each object inside the square brackets.

There are 4 product objects inside the 'products' array.