Batch update patterns in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this batch update response?

Consider a REST API that accepts a batch update request for multiple user records. The server responds with a JSON object summarizing the update results.

{
  "results": [
    {"id": 1, "status": "updated"},
    {"id": 2, "status": "not_found"},
    {"id": 3, "status": "updated"}
  ],
  "summary": {
    "updated": 2,
    "not_found": 1
  }
}

What is the value of response.summary.updated?

A 0

B 3

C 1

D 2

💡 Hint

Count how many items have status "updated" in the results array.

The summary field shows the count of updated records. Since two records have status "updated", the value is 2.

🧠 Conceptual

intermediate

Which HTTP method is most appropriate for batch updates?

You want to update multiple resources in a single REST API call. Which HTTP method should you use according to REST principles?

A POST

B PUT

C GET

D DELETE

💡 Hint

Think about which method is used to replace or update resources.

PUT is used to update or replace resources. For batch updates, a PUT request with a list of updates is appropriate.

🔧 Debug

advanced

Why does this batch update API return a 400 error?

Given this batch update request payload:

{
  "updates": [
    {"id": 1, "name": "Alice"},
    {"name": "Bob"}
  ]
}

The server responds with HTTP 400 Bad Request. What is the most likely cause?

A Server timeout

B Invalid HTTP method used

C Missing 'id' field in one update object

D Empty updates array

💡 Hint

Check if all update objects have required fields.

Each update must specify the resource ID to update. The second object lacks 'id', causing the 400 error.

📝 Syntax

advanced

Which JSON payload is valid for a batch update?

Choose the valid JSON payload for updating multiple items in one request.

A { "updates": [{ "id": 1, "value": "x" }, { "id": 2, "value": "y" }] }

B { "updates": { "id": 1, "value": "x" }, { "id": 2, "value": "y" } }

C [ { "id": 1, "value": "x" }, { "id": 2, "value": "y" } ]

D { "updates": [ { "id": 1, "value": "x" }, { "id": 2, "value": "y" } ] }

💡 Hint

Check for proper JSON object and array syntax.

Option A correctly wraps the array in an object with key 'updates' and uses proper JSON syntax.

🚀 Application

expert

How many items are updated after this batch request?

A batch update request sends the following payload:

{
  "updates": [
    {"id": 1, "status": "active"},
    {"id": 2, "status": "inactive"},
    {"id": 3, "status": "active"},
    {"id": 4, "status": "active"}
  ]
}

The server processes the batch and returns this response:

{
  "results": [
    {"id": 1, "status": "updated"},
    {"id": 2, "status": "error", "message": "Invalid status"},
    {"id": 3, "status": "updated"},
    {"id": 4, "status": "updated"}
  ]
}

How many items were successfully updated?

A 3

B 4

C 2

D 1

💡 Hint

Count how many results have status "updated".

Three items have status "updated"; one has an error.