Resource identifiers in URLs in Rest API - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a resource identifier in a URL?

A resource identifier in a URL is the part that specifies the exact resource you want to access on a server, like a user, product, or article.

beginner

Why do REST APIs use resource identifiers in URLs?

REST APIs use resource identifiers in URLs to clearly point to specific data or objects, making it easy to find, update, or delete them.

beginner

Example: In the URL https://api.example.com/users/123, what does 123 represent?

123 is the resource identifier that points to a specific user with ID 123.

intermediate

How should resource identifiers be structured in URLs?

Resource identifiers should be simple, unique, and human-readable when possible, often using numbers or strings to identify resources clearly.

beginner

What is the difference between a resource and a resource identifier in a URL?

A resource is the actual data or object (like a user or product), while the resource identifier is the part of the URL that points to that specific resource.

In REST APIs, what does the resource identifier in a URL do?

A Specifies the data format

B Defines the server location

C Specifies the exact resource to access

D Sets the HTTP method

The resource identifier tells the API which specific resource you want to work with.

Which part of this URL is the resource identifier?
https://api.shop.com/products/456

A 456

B products

C https://api.shop.com

D shop.com

The number 456 identifies the specific product resource.

Why is it important for resource identifiers to be unique?

A To encrypt the data

B To speed up the internet

C To change the server location

D To avoid confusion between different resources

Unique identifiers ensure each resource can be found without mix-ups.

Which HTTP method usually uses resource identifiers to delete a resource?

A DELETE

B GET

C POST

D PUT

DELETE requests target a resource identified by the URL to remove it.

What is a good practice for resource identifiers in URLs?

A Use long random strings

B Use simple and readable IDs

C Include spaces and special characters

D Use only uppercase letters

Simple and readable IDs make URLs easier to understand and use.

Explain what a resource identifier is and why it is important in REST API URLs.

Think about how URLs point to specific data.

Describe how you would structure a URL to access a specific product in an online store API.

Use a simple example with product ID.

Practice

1. What is the main purpose of resource identifiers in REST API URLs?

easy

A. To uniquely identify a specific resource

B. To specify the HTTP method used

C. To define the server address

D. To set the response format

Solution

1. Step 1: Understand resource identifiers

   Resource identifiers are unique parts of a URL that point to a specific item or resource.

2. Step 2: Identify their role in REST APIs

   They help the server know exactly which resource the client wants to access or modify.

3. Final Answer:

   To uniquely identify a specific resource -> Option A

4. Quick Check:

   Resource identifiers = unique resource ID [OK]

Hint: Resource IDs point to one item in the URL [OK]

Common Mistakes:

• Confusing resource identifiers with HTTP methods
• Thinking resource identifiers define server location
• Mixing resource identifiers with response formats

2. Which of the following is the correct way to include a resource identifier for a user with ID 42 in a REST API URL?

easy

A. /users#42

B. /users?id=42

C. /users/42/details

D. /users/42

Solution

1. Step 1: Identify the standard REST URL format

   Resource identifiers usually come directly after the resource name separated by a slash.

2. Step 2: Check each option

   /users/42 uses "/users/42" which correctly places the ID after the resource name. /users?id=42 uses a query parameter, which is less common for resource identification. /users/42/details adds extra path which may refer to a sub-resource. /users#42 uses a fragment which is not for resource IDs.

3. Final Answer:

   /users/42 -> Option D

4. Quick Check:

   Resource ID follows resource name with slash [OK]

Hint: Resource ID follows resource name with a slash / [OK]

Common Mistakes:

• Using query parameters instead of path segments
• Adding extra path parts that change meaning
• Using URL fragments (#) for resource IDs

3. Given the URL /products/123/reviews/456, which resource does the identifier 456 represent?

medium

A. Product with ID 456

B. Review with ID 456 for product 123

C. Product with ID 123

D. All reviews for product 456

Solution

1. Step 1: Break down the URL path

   The URL has two resource names: "products" and "reviews" with IDs 123 and 456 respectively.

2. Step 2: Understand the hierarchy

   "reviews/456" comes after "products/123", so 456 is the review ID related to product 123.

3. Final Answer:

   Review with ID 456 for product 123 -> Option B

4. Quick Check:

   Last ID is for last resource in URL [OK]

Hint: Last ID belongs to the last resource named [OK]

Common Mistakes:

• Mixing IDs and thinking 456 is a product ID
• Ignoring resource hierarchy in URL
• Assuming IDs apply to all resources

4. Identify the error in this REST API URL for accessing order 789: /orders/ 789

medium

A. The resource identifier should be before the resource name

B. There should be no slash between resource name and ID

C. The ID should be part of the path, not separate

D. The URL is correct as is

Solution

1. Step 1: Analyze the URL structure

   The URL shows /orders/ and then 789 separately, which suggests the ID is not part of the path.

2. Step 2: Understand correct resource ID placement

   The ID should be directly after the resource name in the same path segment, like /orders/789.

3. Final Answer:

   The ID should be part of the path, not separate -> Option C

4. Quick Check:

   Resource ID must be in the path segment [OK]

Hint: Resource ID must be in the same path segment [OK]

Common Mistakes:

• Placing ID outside the URL path
• Removing the slash between resource and ID
• Thinking resource ID comes before resource name

5. You want to design a REST API URL to access a comment with ID 555 on a post with ID 101. Which URL correctly uses resource identifiers to reflect this nested relationship?

hard

A. /posts/101/comments/555

B. /comments/555/posts/101

C. /posts/comments/555/101

D. /posts/555/comments/101

Solution

1. Step 1: Understand resource hierarchy

   The comment belongs to a post, so the post resource should come first in the URL.

2. Step 2: Check each URL option

   /posts/101/comments/555 correctly places the post ID first, then the comments resource with its ID. Other options mix the order or IDs incorrectly.

3. Final Answer:

   /posts/101/comments/555 -> Option A

4. Quick Check:

   Parent resource ID before child resource ID [OK]

Hint: Parent resource ID comes before child resource ID in URL [OK]

Common Mistakes:

• Reversing parent and child resource order
• Mixing IDs between resources
• Placing IDs in wrong path segments