Sparse fieldsets (select fields) in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this REST API response when using sparse fieldsets?

Given the API request GET /articles?fields[articles]=title,author, what fields will the response JSON include for each article?

Rest API

{
  "data": [
    {"id": "1", "type": "articles", "attributes": {"title": "JSON API paints my bikeshed!", "body": "The shortest article ever.", "author": "John"}},
    {"id": "2", "type": "articles", "attributes": {"title": "Rails is Omakase", "body": "Rails is a web-application framework.", "author": "Jane"}}
  ]
}

A {"data":[{"id":"1","type":"articles","attributes":{"title":"JSON API paints my bikeshed!","body":"The shortest article ever."}},{"id":"2","type":"articles","attributes":{"title":"Rails is Omakase","body":"Rails is a web-application framework."}}]}

B {"data":[{"id":"1","type":"articles","attributes":{"body":"The shortest article ever.","author":"John"}},{"id":"2","type":"articles","attributes":{"body":"Rails is a web-application framework.","author":"Jane"}}]}

C {"data":[{"id":"1","type":"articles","attributes":{"title":"JSON API paints my bikeshed!","author":"John"}},{"id":"2","type":"articles","attributes":{"title":"Rails is Omakase","author":"Jane"}}]}

D {"data":[{"id":"1","type":"articles","attributes":{"title":"JSON API paints my bikeshed!"}},{"id":"2","type":"articles","attributes":{"title":"Rails is Omakase"}}]}

💡 Hint

Look at the fields[articles] parameter and which attributes it selects.

The sparse fieldset fields[articles]=title,author means only title and author fields are included in the attributes object for each article. Other fields like body are excluded.

🧠 Conceptual

intermediate

Why use sparse fieldsets in REST API responses?

What is the main benefit of using sparse fieldsets (select fields) in REST API responses?

A To reduce the amount of data sent over the network by including only needed fields

B To encrypt the response data for security

C To force the client to request all fields explicitly every time

D To increase the number of fields returned for better debugging

💡 Hint

Think about network speed and data size.

Sparse fieldsets help reduce bandwidth and improve performance by sending only the fields the client needs, avoiding unnecessary data transfer.

🔧 Debug

advanced

Identify the error in this sparse fieldset query parameter

Which option shows the correct sparse fieldset syntax to request only the name and email fields for users resource?

Rest API

GET /users?fields[users]=name,email

A GET /users?fields[users]:name,email

B GET /users?fields[users]=name,email

C GET /users?fields(users)=name,email

D GET /users?fields=users(name,email)

💡 Hint

Check the correct syntax for specifying fields in JSON API query parameters.

The correct syntax uses square brackets with the resource name as the key and a comma-separated list of fields as the value, like fields[users]=name,email.

❓ Predict Output

advanced

What is the output when requesting sparse fieldsets with an invalid field?

Given the request GET /articles?fields[articles]=title,summary but the summary field does not exist in the API, what is the expected behavior or output?

A {"errors":[{"status":"400","title":"Invalid field","detail":"Field 'summary' is not recognized for resource 'articles'."}]}

B {"data":[{"id":"1","type":"articles","attributes":{"title":"JSON API paints my bikeshed!"}}]}

C {"data":[{"id":"1","type":"articles","attributes":{"title":"JSON API paints my bikeshed!","summary":null}}]}

D {"data":[{"id":"1","type":"articles","attributes":{"title":"JSON API paints my bikeshed!","summary":""}}]}

💡 Hint

Consider how APIs handle requests for unknown fields.

Most APIs return an error response indicating the requested field is invalid rather than silently ignoring or returning null values.

🚀 Application

expert

How to combine sparse fieldsets with includes to optimize API response?

You want to request articles with only the title and author fields, and include the comments relationship but only the body field of comments. Which query string correctly achieves this?

A GET /articles?include=comments&fields[articles]=title,author,comments&fields[comments]=body

B GET /articles?fields=title,author&include=comments&fields=body

C GET /articles?fields[articles]=title,author&include=comments&fields[comments]=body,author

D GET /articles?fields[articles]=title,author&include=comments&fields[comments]=body

💡 Hint

Remember to specify fields separately for each resource type.

Option D correctly uses sparse fieldsets for both articles and comments resources and includes the comments relationship.