Partial success handling in Rest API - Step-by-Step Execution

Concept Flow - Partial success handling

Client sends request

↓

Server processes items

↓

Check each item result

↓

Collect successes

↓

Build partial success response

↓

Send response to client

The server processes each item in a request, collects successes and failures separately, then sends a response showing which parts succeeded and which failed.

Execution Sample

Rest API

POST /batch_process
Request: {items: [1,2,3]}
Process each item:
 - item 1: success
 - item 2: fail
 - item 3: success
Response: {successes: [1,3], failures: [2]}

This example shows a batch API processing multiple items, reporting which succeeded and which failed.

Execution Table

Step	Item	Process Result	Success List	Failure List	Action
1	1	Success	[1]	[]	Add to success list
2	2	Failure	[1]	[2]	Add to failure list
3	3	Success	[1,3]	[2]	Add to success list
4	-	-	[1,3]	[2]	Build response with partial success
5	-	-	[1,3]	[2]	Send response to client

💡 All items processed; response sent with successes and failures separated

Variable Tracker

Variable	Start	After 1	After 2	After 3	Final
success_list	[]	[1]	[1]	[1,3]	[1,3]
failure_list	[]	[]	[2]	[2]	[2]

Key Moments - 2 Insights

Why do we keep successes and failures separate instead of stopping at the first failure?

Because the execution_table shows the server processes all items (rows 1-3) before responding, allowing partial success reporting.

How does the server know which items succeeded or failed?

The process result column in the execution_table (rows 1-3) shows each item's outcome, which updates success_list or failure_list accordingly.

Visual Quiz - 3 Questions

Look at the execution_table at step 2. What is the failure_list value?

A [2]

B []

C [1]

D [1,3]

💡 Hint

Check the failure_list column at step 2 in the execution_table.

At which step does the server build the partial success response?

A Step 1

B Step 3

C Step 4

D Step 5

💡 Hint

Look at the Action column in the execution_table for the step mentioning response building.

If item 2 had succeeded, how would success_list look after step 3?

A [1,3]

B [1,2,3]

C [2,3]

D [1,2]

💡 Hint

Refer to variable_tracker success_list values and imagine item 2 success at step 3.

Concept Snapshot

Partial success handling in REST APIs:
- Process each item independently
- Collect successes and failures separately
- Respond with both lists
- Allows client to know what worked and what failed
- Improves robustness in batch operations

Full Transcript

Partial success handling means when a server processes multiple items in one request, it does not stop at the first failure. Instead, it processes all items, keeps track of which succeeded and which failed, and sends a response showing both lists. This helps clients understand exactly what worked and what did not. The execution table shows each item processed step-by-step, updating success and failure lists. The server builds the response after all items are processed, then sends it back. This approach is common in batch APIs to improve reliability and feedback.

Practice

1. What does HTTP 207 Multi-Status indicate in REST API partial success handling?

easy

A. Some parts of the request succeeded while others failed

B. The entire request failed due to server error

C. The request was redirected to another URL

D. The request was successful with no errors

Solution

1. Step 1: Understand HTTP 207 Multi-Status meaning

   HTTP 207 is used to report multiple status codes for different parts of a single request.

2. Step 2: Relate to partial success handling

   This status code indicates that some parts succeeded and others failed, providing detailed results.

3. Final Answer:

   Some parts of the request succeeded while others failed -> Option A

4. Quick Check:

   HTTP 207 = Partial success [OK]

Hint: 207 means mixed results, not full success or failure [OK]

Common Mistakes:

• Confusing 207 with 200 OK
• Thinking 207 means full failure
• Assuming 207 is a redirect status

2. Which of the following is the correct way to represent partial success in a REST API response?

easy

A. HTTP 404 with error message

B. HTTP 200 with empty body

C. HTTP 207 with JSON detailing success and failure

D. HTTP 500 with stack trace

Solution

1. Step 1: Identify correct HTTP status for partial success

   HTTP 207 Multi-Status is designed to show multiple results in one response.

2. Step 2: Confirm response format

   Using JSON to detail which parts succeeded or failed is the standard approach.

3. Final Answer:

   HTTP 207 with JSON detailing success and failure -> Option C

4. Quick Check:

   207 + JSON = Partial success response [OK]

Hint: Use 207 with JSON for partial success, not 200 or errors [OK]

Common Mistakes:

• Using 200 OK without details
• Returning 404 for partial success
• Sending server error 500 instead of partial status

3. Given this partial success JSON response, what is the status of item with ID 3?

{
  "responses": [
    {"id": 1, "status": "success"},
    {"id": 2, "status": "failure", "error": "Invalid data"},
    {"id": 3, "status": "success"}
  ]
}

medium

A. Failure due to invalid data

B. Success

C. Unknown status

D. Pending

Solution

1. Step 1: Locate item with ID 3 in JSON

   Item with ID 3 has "status": "success" in the responses array.

2. Step 2: Interpret the status value

   The status "success" means the operation for item 3 succeeded.

3. Final Answer:

   Success -> Option B

4. Quick Check:

   ID 3 status = success [OK]

Hint: Check the status field for the item ID in JSON [OK]

Common Mistakes:

• Confusing failure of other items with this one
• Assuming missing error means failure
• Ignoring the status field

4. You receive this HTTP response code and body from a batch update API:

HTTP/1.1 207 Multi-Status
{
  "results": [
    {"item": "A", "status": "success"},
    {"item": "B", "status": "fail", "error": "Timeout"}
  ]
}

What is the main issue in this response?

medium

A. Incorrect HTTP status code for partial success

B. JSON format is invalid

C. Missing Content-Type header

D. The status value "fail" should be "failure" or "error"

Solution

1. Step 1: Check HTTP status code usage

   HTTP 207 Multi-Status is correct for partial success.

2. Step 2: Verify status field values

   Common practice uses "success" and "failure" or "error"; "fail" is inconsistent and may cause confusion.

3. Final Answer:

   The status value "fail" should be "failure" or "error" -> Option D

4. Quick Check:

   Status values must be consistent and clear [OK]

Hint: Use standard status words like 'success' and 'failure' [OK]

Common Mistakes:

• Thinking 207 is wrong here
• Ignoring inconsistent status wording
• Assuming JSON is invalid without checking

5. You design a REST API endpoint that processes a list of user updates. Some updates succeed, others fail due to validation errors. How should you structure the response to clearly communicate partial success?

hard

A. Return HTTP 207 with a JSON array showing each user's update status and error if any

B. Return HTTP 400 with a generic error message for all failures

C. Return HTTP 200 with a simple success message ignoring failures

D. Return HTTP 500 with server error details

Solution

1. Step 1: Identify the need for partial success reporting

   Since some updates succeed and others fail, the response must show both results clearly.

2. Step 2: Choose appropriate HTTP status and response format

   HTTP 207 Multi-Status with detailed JSON per user update is the best practice to communicate partial success.

3. Final Answer:

   Return HTTP 207 with a JSON array showing each user's update status and error if any -> Option A

4. Quick Check:

   207 + detailed JSON = clear partial success [OK]

Hint: Use 207 and detailed JSON for mixed success/failure results [OK]

Common Mistakes:

• Ignoring failed updates in response
• Using 200 OK without details
• Returning generic errors instead of per-item status