Related resource links in Rest API - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are related resource links in REST APIs?

Related resource links are URLs provided in API responses that point to other resources connected to the current one. They help clients navigate between related data easily.

beginner

Why use related resource links instead of embedding all data in one response?

Using related resource links keeps responses smaller and faster. It allows clients to fetch only the data they need when they need it, improving performance and flexibility.

intermediate

How are related resource links typically included in REST API responses?

They are often included in a dedicated section like `_links` or `links` in the JSON response, with keys describing the relation and values as URLs to the related resources.

intermediate

What is HATEOAS and how does it relate to related resource links?

HATEOAS (Hypermedia As The Engine Of Application State) is a REST principle where responses include links to related actions or resources, guiding clients through the API dynamically.

beginner

Give an example of a related resource link in a REST API JSON response.

Example: { "_links": { "author": { "href": "https://api.example.com/users/123" } } } means the current resource has a related author resource at the given URL.

What is the main purpose of related resource links in REST APIs?

A To connect related data resources for easy navigation

B To increase the size of API responses

C To embed all data in one response

D To encrypt API responses

Related resource links help clients find and access connected data resources easily.

Where are related resource links commonly found in a REST API JSON response?

A In a dedicated '_links' or 'links' section

B Inside the HTTP headers only

C As part of the URL query parameters

D In the response status code

They are usually included in a '_links' or 'links' section within the JSON body.

Which REST principle emphasizes including related resource links in responses?

A CRUD

B SOAP

C HATEOAS

D OAuth

HATEOAS stands for Hypermedia As The Engine Of Application State and promotes including links in responses.

What is a benefit of using related resource links instead of embedding all related data?

A Less flexible API design

B Slower API responses

C More complex client code

D Smaller response size and on-demand data fetching

Links keep responses small and allow clients to fetch related data only when needed.

In the example { "_links": { "author": { "href": "https://api.example.com/users/123" } } }, what does the 'author' link represent?

A An unrelated external website

B A related resource URL for the author

C The current resource's ID

D The API version number

The 'author' key points to a URL where the related author resource can be found.

Explain what related resource links are in REST APIs and why they are useful.

Think about how APIs help clients find connected data without sending everything at once.

Describe how related resource links are typically structured in a JSON response and how clients use them.

Consider the JSON format and how clients follow URLs to get more info.

Practice

1. What is the main purpose of related resource links in a REST API?

easy

A. To store user credentials securely

B. To speed up the server response time

C. To connect related data so users can easily navigate between resources

D. To encrypt data sent over the network

Solution

1. Step 1: Understand the role of related resource links

   Related resource links provide connections between different pieces of data in an API, making it easier to find connected information.

2. Step 2: Identify the correct purpose

   Among the options, only connecting related data for easy navigation matches the purpose of related resource links.

3. Final Answer:

   To connect related data so users can easily navigate between resources -> Option C

4. Quick Check:

   Related resource links = connect data [OK]

Hint: Related links help users jump between connected data [OK]

Common Mistakes:

• Confusing related links with security features
• Thinking related links speed up server
• Assuming related links encrypt data

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

easy

A. "related": "https://api.example.com/users/123/orders"

B. "related": users/123/orders

C. "related":

D. "related": {url: "https://api.example.com/users/123/orders"}

Solution

1. Step 1: Check JSON syntax for URLs

   In JSON, URLs should be strings enclosed in double quotes without angle brackets or unquoted text.

2. Step 2: Identify the correct format

   "related": "https://api.example.com/users/123/orders" correctly uses a string with the full URL in quotes. Options B and C are invalid JSON strings, and D uses an object instead of a string.

3. Final Answer:

   "related": "https://api.example.com/users/123/orders" -> Option A

4. Quick Check:

   Related link URL must be a quoted string [OK]

Hint: URLs in JSON must be quoted strings without brackets [OK]

Common Mistakes:

• Leaving URLs unquoted
• Using angle brackets around URLs
• Using objects instead of strings for links

3. Given this JSON snippet from a REST API response:

{
  "id": 10,
  "name": "Book",
  "related": "https://api.example.com/books/10/author"
}

What does the related link represent?

medium

A. The URL to list all books

B. The URL to update the book information

C. The URL to delete the book

D. The URL to fetch the author details of the book

Solution

1. Step 1: Analyze the related link URL

   The URL ends with "/books/10/author", which suggests it points to the author of book with ID 10.

2. Step 2: Match URL purpose with options

   Only The URL to fetch the author details of the book correctly describes this as fetching author details. Other options refer to book update, delete, or list, which do not match the URL.

3. Final Answer:

   The URL to fetch the author details of the book -> Option D

4. Quick Check:

   Related link points to connected resource = author [OK]

Hint: Look at URL path to identify related resource type [OK]

Common Mistakes:

• Assuming related link is for update or delete
• Confusing related link with main resource URL
• Ignoring the path after resource ID

4. You have this REST API response snippet:

{
  "id": 5,
  "name": "Alice",
  "related": "api.example.com/users/5/friends"
}

Why might this related link cause problems for clients?

medium

A. The related link points to a wrong resource

B. The URL is missing the protocol (http:// or https://)

C. The JSON format is invalid

D. The related link is too long

Solution

1. Step 1: Check the related link format

   The link "api.example.com/users/5/friends" lacks the protocol prefix like "https://" which is required for clients to resolve the full URL.

2. Step 2: Identify the impact

   Without the protocol, clients may fail to fetch the related resource or assume a wrong protocol, causing errors.

3. Final Answer:

   The URL is missing the protocol (http:// or https://) -> Option B

4. Quick Check:

   Related links need full URLs with protocol [OK]

Hint: Always include http:// or https:// in related links [OK]

Common Mistakes:

• Ignoring missing protocol in URLs
• Thinking JSON is invalid due to link format
• Assuming link length causes issues

5. You want to design a REST API response for a blog post that includes related links to the author and comments. Which JSON structure correctly shows these related resource links?

hard

A. {
"id": 101,
"title": "REST APIs",
"related": {
"author": "https://api.example.com/users/42",
"comments": "https://api.example.com/posts/101/comments"
}
}

B. {
"id": 101,
"title": "REST APIs",
"related": [
"https://api.example.com/users/42",
"https://api.example.com/posts/101/comments"
]
}

C. {
"id": 101,
"title": "REST APIs",
"related": "https://api.example.com/users/42, https://api.example.com/posts/101/comments"
}

D. {
"id": 101,
"title": "REST APIs",
"related": null
}

Solution

1. Step 1: Understand how to represent multiple related links

   When multiple related resources exist, it's best to use an object with named keys for clarity, not a list or comma-separated string.

2. Step 2: Evaluate each option

   { "id": 101, "title": "REST APIs", "related": { "author": "https://api.example.com/users/42", "comments": "https://api.example.com/posts/101/comments" } } uses an object with keys "author" and "comments" pointing to URLs, which is clear and correct. { "id": 101, "title": "REST APIs", "related": [ "https://api.example.com/users/42", "https://api.example.com/posts/101/comments" ] } uses a list without labels, making it unclear. { "id": 101, "title": "REST APIs", "related": "https://api.example.com/users/42, https://api.example.com/posts/101/comments" } uses a string with comma-separated URLs, which is not standard. { "id": 101, "title": "REST APIs", "related": null } has null, which provides no links.

3. Final Answer:

   Use an object with named related links for clarity -> Option A

4. Quick Check:

   Multiple related links = object with named URLs [OK]

Hint: Use named keys for multiple related links in JSON [OK]

Common Mistakes:

• Using arrays without labels for related links
• Combining URLs in one string
• Leaving related links empty or null