Link relations in responses in Rest API - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a 'self' link relation in the JSON response.

Rest API

response = {
  "_links": {
    "self": {"href": [1]
  }
}

Drag options to blanks, or click blank then click option'

A"/items"

B"/api/items/1"

C"http://example.com/api/items"

D"items/1"

Attempts:

3 left

💡 Hint

Common Mistakes

Using relative paths without leading slash

Omitting quotes around the URL

The 'self' link relation should contain the full path to the current resource, typically starting with a slash.

2fill in blank

medium

Complete the code to add a 'next' link relation pointing to the next page.

Rest API

response = {
  "_links": {
    "next": {"href": [1]
  }
}

Drag options to blanks, or click blank then click option'

A"/api/items?page=2"

B"/api/items?page=3"

C"/api/items?page=1"

D"/api/items?page=0"

Attempts:

3 left

💡 Hint

Common Mistakes

Using the current page number instead of next

Using invalid page numbers

The 'next' link should point to the next page, which is page 2 in this example.

3fill in blank

hard

Fix the error in the link relation key to correctly represent the 'prev' link.

Rest API

response = {
  "_links": {
    [1]: {"href": "/api/items?page=1"}
  }
}

Drag options to blanks, or click blank then click option'

A"back"

B"previous"

C"prev"

D"before"

Attempts:

3 left

💡 Hint

Common Mistakes

Using non-standard relation names like 'previous' or 'back'

The standard link relation for the previous page is 'prev'.

4fill in blank

hard

Fill both blanks to add 'self' and 'related' link relations in the response.

Rest API

response = {
  "_links": {
    [1]: {"href": "/api/items/5"},
    [2]: {"href": "/api/items/5/related"}
  }
}

Drag options to blanks, or click blank then click option'

A"self"

B"related"

C"next"

D"prev"

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up 'next' or 'prev' with 'related'

'self' points to the current resource, and 'related' points to related resources.

5fill in blank

hard

Fill all three blanks to create a response with 'self', 'next', and 'prev' link relations.

Rest API

response = {
  "_links": {
    [1]: {"href": "/api/items/10"},
    [2]: {"href": "/api/items?page=11"},
    [3]: {"href": "/api/items?page=9"}
  }
}

Drag options to blanks, or click blank then click option'

A"self"

B"next"

C"prev"

D"related"

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'related' instead of 'prev' or 'next'

'self' is the current item, 'next' is the next page, and 'prev' is the previous page.

Practice

1. What is the main purpose of using link relations in REST API responses?

easy

A. To define the HTTP methods allowed on a resource

B. To encrypt the data sent between client and server

C. To specify the data format like JSON or XML

D. To describe how different resources are connected and provide URLs for related actions

Solution

1. Step 1: Understand link relations concept

   Link relations describe the relationship between resources and provide URLs to related resources or actions.

2. Step 2: Identify the purpose in REST API responses

   They help clients navigate the API by following links instead of hardcoding URLs.

3. Final Answer:

   To describe how different resources are connected and provide URLs for related actions -> Option D

4. Quick Check:

   Link relations = resource connections and URLs [OK]

Hint: Link relations connect resources with URLs in responses [OK]

Common Mistakes:

• Confusing link relations with data encryption
• Thinking link relations define data format
• Mixing link relations with HTTP method definitions

2. Which of the following is the correct way to include a link relation in a JSON REST API response?

easy

A. "_links": { "self": { "href": "/users/123" } }

B. "links": [ { "url": "/users/123" } ]

C. "link": "/users/123"

D. "href": { "self": "/users/123" }

Solution

1. Step 1: Recall standard link relation format in JSON

   Standard uses a _links object with named relations like self containing an href URL.

2. Step 2: Match the correct JSON structure

   "_links": { "self": { "href": "/users/123" } } matches this format exactly, others do not follow the standard naming or structure.

3. Final Answer:

   "_links": { "self": { "href": "/users/123" } } -> Option A

4. Quick Check:

   Standard link relation = _links with self and href [OK]

Hint: Look for _links with self and href keys [OK]

Common Mistakes:

• Using 'links' instead of '_links'
• Missing 'href' inside the relation object
• Using arrays instead of objects for link relations

3. Given this JSON response snippet:

{
  "_links": {
    "self": { "href": "/orders/42" },
    "cancel": { "href": "/orders/42/cancel" }
  }
}

What URL should a client use to cancel order 42?

medium

A. /orders/42

B. /orders/cancel/42

C. /orders/42/cancel

D. /orders/42/cancelled

Solution

1. Step 1: Locate the 'cancel' link relation in the JSON

   The 'cancel' relation has the href value "/orders/42/cancel" which is the URL to cancel the order.

2. Step 2: Confirm the correct URL for cancellation

   The client should use the URL exactly as given in the 'cancel' href to perform the cancel action.

3. Final Answer:

   /orders/42/cancel -> Option C

4. Quick Check:

   Cancel URL = /orders/42/cancel [OK]

Hint: Use the href under the 'cancel' link relation [OK]

Common Mistakes:

• Using the 'self' URL instead of 'cancel'
• Rearranging URL parts incorrectly
• Guessing URL instead of reading from response

4. You receive this partial JSON response:

{
  "_links": {
    "self": { "href": "/products/7" },
    "edit": { "url": "/products/7/edit" }
  }
}

What is wrong with the link relations in this response?

medium

A. The 'edit' relation uses 'url' instead of 'href'

B. The 'self' relation should not be included

C. The 'href' value for 'self' is missing a domain

D. The '_links' key should be named 'links'

Solution

1. Step 1: Check the property names inside link relations

   Standard link relations use 'href' to specify the URL, not 'url'.

2. Step 2: Identify the incorrect property

   The 'edit' relation incorrectly uses 'url' instead of 'href'.

3. Final Answer:

   The 'edit' relation uses 'url' instead of 'href' -> Option A

4. Quick Check:

   Link relation URLs must use 'href' key [OK]

Hint: Link URLs always use 'href', not 'url' [OK]

Common Mistakes:

• Thinking 'url' is acceptable instead of 'href'
• Expecting full domain in href for relative URLs
• Renaming '_links' to 'links' incorrectly

5. You want to design a REST API response for a blog post that includes links to the post itself, the author's profile, and comments. Which JSON structure correctly uses link relations to represent these?

hard

A. { "links": [ { "rel": "self", "url": "/posts/10" }, { "rel": "author", "url": "/users/5" }, { "rel": "comments", "url": "/posts/10/comments" } ] }

B. { "_links": { "self": { "href": "/posts/10" }, "author": { "href": "/users/5" }, "comments": { "href": "/posts/10/comments" } } }

C. { "_links": { "self": "/posts/10", "author": "/users/5", "comments": "/posts/10/comments" } }

D. { "_links": { "self": { "url": "/posts/10" }, "author": { "url": "/users/5" }, "comments": { "url": "/posts/10/comments" } } }

Solution

1. Step 1: Recall the correct link relation format

   Each link relation should be an object with an 'href' key inside the '_links' object.

2. Step 2: Evaluate each option's structure

   { "_links": { "self": { "href": "/posts/10" }, "author": { "href": "/users/5" }, "comments": { "href": "/posts/10/comments" } } } correctly uses '_links' with 'self', 'author', and 'comments' keys, each having an 'href' URL. Options B and D use 'url' instead of 'href', and C uses strings instead of objects.

3. Final Answer:

   { "_links": { "self": { "href": "/posts/10" }, "author": { "href": "/users/5" }, "comments": { "href": "/posts/10/comments" } } } -> Option B

4. Quick Check:

   Use '_links' with objects containing 'href' URLs [OK]

Hint: Use '_links' with 'href' keys for each relation [OK]

Common Mistakes:

• Using 'url' instead of 'href' for links
• Using arrays instead of objects for link relations
• Assigning string URLs directly without 'href' objects