HAL format overview in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this HAL JSON snippet?

Given this HAL JSON snippet, what is the value of the 'self' link href?

Rest API

{
  "_links": {
    "self": { "href": "/orders/123" },
    "next": { "href": "/orders/124" },
    "find": { "href": "/orders{?id}", "templated": true }
  },
  "total": 1,
  "_embedded": {
    "orders": [
      { "id": 123, "status": "shipped" }
    ]
  }
}

A "/orders{?id}"

B "/orders/123"

C "/orders/124"

D "/orders/125"

💡 Hint

Look inside the _links object for the 'self' key.

The 'self' link in HAL points to the current resource URL, which is '/orders/123' here.

🧠 Conceptual

intermediate

What is the purpose of the _embedded section in HAL?

In HAL format, what does the _embedded section do?

A It contains related resources embedded inside the current resource.

B It lists all available HTTP methods.

C It specifies the API version used.

D It defines HTTP headers for the response.

💡 Hint

Think about how HAL helps clients get related data in one response.

The _embedded section holds related resources so clients can access them without extra requests.

🔧 Debug

advanced

What error does this HAL JSON cause?

This HAL JSON snippet is invalid. What error will it cause when parsed?

Rest API

{
  "_links": {
    "self": { "href": "/users/1" },
    "friends": [
      { "href": "/users/2" },
      { "href": "/users/3" }
    ]
  },
  "name": "Alice",
  "age": 30
}

A No error, valid HAL JSON

B TypeError because 'friends' should not be an array

C KeyError because '_embedded' is missing

D SyntaxError due to missing comma between 'name' and 'age'

💡 Hint

Check JSON syntax carefully between properties.

There is a missing comma after the 'name' property, causing a JSON syntax error.

📝 Syntax

advanced

Which option correctly represents a templated link in HAL?

Choose the correct HAL syntax for a templated link to search orders by id.

A "search": { "href": "/orders/{id}", "templated": true }

B "search": { "href": "/orders?id", "templated": false }

C "search": { "href": "/orders{?id}", "templated": true }

D "search": { "href": "/orders?id", "templated": true }

💡 Hint

Templated links use curly braces with question mark for optional query params.

Option C correctly uses the URI template syntax with {?id} and sets templated to true.

🚀 Application

expert

How many items are in the embedded orders list?

Given this HAL JSON, how many orders are embedded inside the _embedded section? { "_links": { "self": { "href": "/orders" } }, "_embedded": { "orders": [ { "id": 101, "status": "pending" }, { "id": 102, "status": "shipped" }, { "id": 103, "status": "delivered" } ] }, "count": 3 }

A 3

B 4

C 0

D 1

💡 Hint

Count the number of objects inside the orders array in _embedded.

There are three order objects inside the orders array in the _embedded section.