Action links for state transitions in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this REST API response with action links?

Given this JSON response from a REST API representing an order, what is the value of the href for the cancel action link?

Rest API

{
  "orderId": "12345",
  "status": "processing",
  "actions": {
    "cancel": {
      "href": "/orders/12345/cancel",
      "method": "POST"
    },
    "track": {
      "href": "/orders/12345/track",
      "method": "GET"
    }
  }
}

A "/orders/12345/track"

B "/orders/cancel/12345"

C "/orders/12345/cancel"

D "/cancel/orders/12345"

💡 Hint

Look for the cancel key inside actions and check its href value.

The cancel action link is defined with href as /orders/12345/cancel. This is the correct URL to trigger the cancel action for order 12345.

🧠 Conceptual

intermediate

Which HTTP method is typically used for state transition actions like 'approve' or 'reject' in REST APIs?

In REST APIs, when you provide action links for state transitions such as 'approve' or 'reject' an item, which HTTP method is most appropriate to use?

A PUT

B POST

C DELETE

D GET

💡 Hint

Think about methods that cause a change in server state but are not idempotent.

POST is commonly used for state transitions that cause a change but are not idempotent, such as 'approve' or 'reject'. GET is for retrieval, DELETE for removal, and PUT for idempotent updates.

🔧 Debug

advanced

Identify the error in this action link JSON for a state transition

What error will occur when a client tries to use this action link to transition the state?

Rest API

{
  "actions": {
    "ship": {
      "href": "/orders/789/ship",
      "method": "GET"
    }
  }
}

A 404 Not Found error because the URL is invalid

B No error; the action link is valid

C SyntaxError due to missing comma

D Using GET method for a state-changing action causes unexpected behavior

💡 Hint

Consider HTTP method semantics for state changes.

GET should be safe and not change state. Using GET for a state transition like 'ship' is incorrect and can cause unexpected behavior or violate REST principles.

📝 Syntax

advanced

Which option correctly represents an action link for a 'complete' state transition in JSON?

Choose the syntactically correct JSON snippet for an action link named 'complete' that uses POST method.

A { "complete": { "href": "/tasks/456/complete", "method": "POST" } }

B { complete: { href: "/tasks/456/complete", method: "POST" } }

C { "complete": { "href": "/tasks/456/complete", "method": POST } }

D { "complete": { "href": "/tasks/456/complete", method: "POST" }

💡 Hint

Remember JSON requires double quotes around keys and string values.

Option A is valid JSON with proper quotes and syntax. Option A misses quotes around keys, C misses quotes around method value, D is missing closing brace.

🚀 Application

expert

How many action links are available for this resource and what are their HTTP methods?

Given this JSON snippet for a resource, count the number of action links and list their HTTP methods.

Rest API

{
  "id": "555",
  "status": "pending",
  "actions": {
    "approve": { "href": "/requests/555/approve", "method": "POST" },
    "reject": { "href": "/requests/555/reject", "method": "POST" },
    "cancel": { "href": "/requests/555/cancel", "method": "DELETE" }
  }
}

A 3 action links: POST, POST, DELETE

B 2 action links: POST, DELETE

C 4 action links: POST, POST, DELETE, GET

D 3 action links: GET, POST, DELETE

💡 Hint

Count all keys inside the actions object and note their methods.

There are three action links: 'approve' (POST), 'reject' (POST), and 'cancel' (DELETE).