Self link for current resource in Rest API - Step-by-Step Execution

Concept Flow - Self link for current resource

Client sends request

↓

Server processes request

↓

Server creates resource representation

↓

Server adds self link (URL to this resource)

↓

Server sends response with self link

↓

Client receives response and can use self link to access resource again

The server adds a URL pointing to the current resource in the response, so the client can easily find or refresh it.

Execution Sample

Rest API

GET /api/books/123 HTTP/1.1
Host: example.com

Response:
{
  "id": 123,
  "title": "Learn REST",
  "_links": {
    "self": { "href": "/api/books/123" }
  }
}

This example shows a GET request for a book resource and the server response including a self link to the same book.

Execution Table

Step	Action	Resource Data	Self Link Added	Response Sent
1	Receive GET request for /api/books/123	None	No	No
2	Fetch book data with id 123	{"id":123,"title":"Learn REST"}	No	No
3	Add self link to resource data	{"id":123,"title":"Learn REST","_links":{"self":{"href":"/api/books/123"}}}	Yes	No
4	Send response with resource data and self link	{"id":123,"title":"Learn REST","_links":{"self":{"href":"/api/books/123"}}}	Yes	Yes
5	Client receives response	Resource data with self link	Yes	Yes

💡 Response sent with self link so client can access the same resource URL again

Variable Tracker

Variable	Start	After Step 2	After Step 3	Final
resource_data	None	{"id":123,"title":"Learn REST"}	{"id":123,"title":"Learn REST","_links":{"self":{"href":"/api/books/123"}}}	{"id":123,"title":"Learn REST","_links":{"self":{"href":"/api/books/123"}}}
self_link_added	False	False	True	True
response_sent	False	False	False	True

Key Moments - 3 Insights

Why do we add a self link to the resource data?

Adding a self link gives the client a direct URL to the current resource, making it easy to retrieve or update it later, as shown in step 3 and 4 of the execution_table.

Is the self link the full URL or just a path?

Often the self link is a relative path like "/api/books/123" to keep responses smaller and flexible, as seen in the resource_data after step 3.

Does the client have to use the self link to get the resource again?

No, the client can use any valid URL, but the self link is a recommended, reliable way to access the exact resource, as emphasized in the final response.

Visual Quiz - 3 Questions

Look at the execution_table, at which step is the self link added to the resource data?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Check the 'Self Link Added' column in the execution_table.

According to variable_tracker, what is the value of 'response_sent' after step 3?

A True

B None

C False

D Undefined

💡 Hint

Look at the 'response_sent' row and the 'After Step 3' column in variable_tracker.

If the self link was missing in the response, what would change in the execution_table?

A The 'Self Link Added' column would be 'No' at step 3 and 4

B The 'Response Sent' would be 'No' at step 4

C The resource data would be empty

D The client would not receive any response

💡 Hint

Focus on the 'Self Link Added' column in the execution_table rows.

Concept Snapshot

Self link in REST API responses:
- Provides URL to current resource
- Usually in '_links' with 'self' key
- Helps clients find or refresh resource
- Often a relative path
- Added before sending response

Full Transcript

When a client requests a resource from a REST API, the server processes the request and fetches the resource data. Before sending the response, the server adds a self link, which is a URL pointing to the same resource. This link is usually included in a '_links' section with a 'self' key. The self link helps the client easily access or refresh the resource later. The response is then sent back including the resource data and the self link. The client receives this and can use the self link to make future requests to the same resource. This process ensures clear navigation and resource identification in REST APIs.

Practice

1. What is the main purpose of a self link in a REST API response?

easy

A. To provide the URL of the current resource for easy access

B. To link to a related but different resource

C. To show the API version used

D. To list all available endpoints in the API

Solution

1. Step 1: Understand the role of self link

   The self link points to the current resource's URL, allowing clients to access or refresh it easily.

2. Step 2: Differentiate from other links

   Other links may point to related resources or metadata, but self specifically means the current resource.

3. Final Answer:

   To provide the URL of the current resource for easy access -> Option A

4. Quick Check:

   Self link = current resource URL [OK]

Hint: Self link always points to the current resource URL [OK]

Common Mistakes:

• Confusing self link with related resource links
• Thinking self link shows API version
• Assuming self link lists all endpoints

2. Which of the following is the correct JSON structure to include a self link for a resource with URL https://api.example.com/items/42?

easy

A. {"links": {"self_link": "https://api.example.com/items/42"}}

B. {"_links": {"self": "https://api.example.com/items/42"}}

C. {"_links": {"current": "https://api.example.com/items/42"}}

D. {"self": "https://api.example.com/items/42"}

Solution

1. Step 1: Identify the standard key names

   The standard way is to use an object named _links containing a self key with the URL string.

2. Step 2: Compare options

   {"_links": {"self": "https://api.example.com/items/42"}} matches the standard exactly. Others use wrong keys or structure.

3. Final Answer:

   {"_links": {"self": "https://api.example.com/items/42"}} -> Option B

4. Quick Check:

   Use _links with self key for self link [OK]

Hint: Use _links object with self key for self link [OK]

Common Mistakes:

• Using 'links' instead of '_links'
• Using 'self_link' or 'current' instead of 'self'
• Placing self URL outside _links object

3. Given this API response snippet, what is the URL to access the current resource?

{
  "id": 10,
  "name": "Book",
  "_links": {
    "self": "https://api.example.com/products/10",
    "category": "https://api.example.com/categories/5"
  }
}

medium

A. https://api.example.com/products/10

B. https://api.example.com/products

C. https://api.example.com/categories/5

D. https://api.example.com/

Solution

1. Step 1: Locate the self link in the _links object

   The self link is under _links with key self, value is the current resource URL.

2. Step 2: Identify the URL value

   The value is "https://api.example.com/products/10", which is the URL for this product resource.

3. Final Answer:

   https://api.example.com/products/10 -> Option A

4. Quick Check:

   Self link URL = https://api.example.com/products/10 [OK]

Hint: Find _links.self for current resource URL [OK]

Common Mistakes:

• Choosing related links like category URL
• Picking base API URL instead of self
• Ignoring the _links object structure

4. You receive this JSON response but the self link is missing:

{
  "id": 5,
  "title": "Article",
  "_links": {
    "related": "https://api.example.com/articles/related"
  }
}

What is the best fix to add a self link for the current resource at https://api.example.com/articles/5?

medium

A. Add "self": "https://api.example.com/articles/5" at the root level

B. Add "self_link": "https://api.example.com/articles/5" inside the _links object

C. Add "self": "https://api.example.com/articles/5" inside the _links object

D. Add "link": "https://api.example.com/articles/5" inside the _links object

Solution

1. Step 1: Identify where self link belongs

   The self link must be inside the _links object with key exactly "self".

2. Step 2: Choose correct key and location

   Add "self": "https://api.example.com/articles/5" inside the _links object adds the correct key "self" with the URL inside _links. Other options use wrong keys or wrong placement.

3. Final Answer:

   Add "self": "https://api.example.com/articles/5" inside the _links object -> Option C

4. Quick Check:

   Self link key = "self" inside _links [OK]

Hint: Self link must be 'self' key inside _links object [OK]

Common Mistakes:

• Using wrong key names like self_link or link
• Placing self link outside _links object
• Omitting the self link entirely

5. You want to design a REST API response for a user resource with ID 7. Which JSON snippet correctly includes a self link and a related link to the user's orders at https://api.example.com/users/7/orders?

hard

A. {
"id": 7,
"name": "Alice",
"_links": {
"self": "https://api.example.com/users/7",
"related": "https://api.example.com/users/7/orders"
}
}

B. {
"id": 7,
"name": "Alice",
"links": {
"self": "https://api.example.com/users/7",
"orders": "https://api.example.com/users/7/orders"
}
}

C. {
"id": 7,
"name": "Alice",
"_links": {
"self_link": "https://api.example.com/users/7",
"orders_link": "https://api.example.com/users/7/orders"
}
}

D. {
"id": 7,
"name": "Alice",
"_links": {
"self": "https://api.example.com/users/7",
"orders": "https://api.example.com/users/7/orders"
}
}

Solution

1. Step 1: Confirm self link key and URL

   The self link must be under _links with key "self" and URL "https://api.example.com/users/7".

2. Step 2: Choose appropriate key for related orders link

   Using "orders" for the orders link is a standard practice to indicate the related resource. { "id": 7, "name": "Alice", "_links": { "self": "https://api.example.com/users/7", "orders": "https://api.example.com/users/7/orders" } } uses "orders" correctly.

3. Step 3: Check other options for correctness

   { "id": 7, "name": "Alice", "_links": { "self": "https://api.example.com/users/7", "orders": "https://api.example.com/users/7/orders" } } uses "orders" key which is standard. { "id": 7, "name": "Alice", "links": { "self": "https://api.example.com/users/7", "orders": "https://api.example.com/users/7/orders" } } uses "links" instead of "_links". { "id": 7, "name": "Alice", "_links": { "self_link": "https://api.example.com/users/7", "orders_link": "https://api.example.com/users/7/orders" } } uses non-standard keys "self_link" and "orders_link". The option with "related": "https://api.example.com/users/7/orders" uses a generic rel name which is less descriptive for the specific orders resource.

4. Final Answer:

   { "id": 7, "name": "Alice", "_links": { "self": "https://api.example.com/users/7", "orders": "https://api.example.com/users/7/orders" } } -> Option D

5. Quick Check:

   Use _links with self and orders keys for current and orders URLs [OK]

Hint: Use _links with self and orders keys for current and orders URLs [OK]

Common Mistakes:

• Using 'links' instead of '_links'
• Using non-standard keys like self_link
• Using generic 'related' instead of specific 'orders'