Batch delete patterns in Rest API - Step-by-Step Execution

Concept Flow - Batch delete patterns

Client sends batch delete request

↓

Server receives request with multiple IDs

↓

Server validates IDs

↓

Delete items

↓

Return success response with status for each item

↓

Client processes response

The client sends a request to delete multiple items at once. The server checks the IDs, deletes valid ones, and returns a detailed response.

Execution Sample

Rest API

DELETE /items?ids=1,2,3,4

Response:
{
  "deleted": [1,2,3],
  "not_found": [4]
}

This example shows a batch delete request with IDs 1 to 4, where item 4 was not found.

Execution Table

Step	Action	Input	Validation Result	Delete Result	Response Output
1	Receive request	ids=1,2,3,4	IDs parsed	-	-
2	Validate ID 1	1	Valid	Deleted	-
3	Validate ID 2	2	Valid	Deleted	-
4	Validate ID 3	3	Valid	Deleted	-
5	Validate ID 4	4	Not found	Not deleted	-
6	Compile response	-	-	-	{"deleted": [1,2,3], "not_found": [4]}
7	Send response	-	-	-	Response sent to client

💡 All IDs processed; response sent with deletion status.

Variable Tracker

Variable	Start	After 1	After 2	After 3	After 4	Final
ids_to_delete	[1,2,3,4]	[2,3,4]	[3,4]	[4]	[]	[]
deleted_ids	[]	[1]	[1,2]	[1,2,3]	[1,2,3]	[1,2,3]
not_found_ids	[]	[]	[]	[]	[4]	[4]

Key Moments - 2 Insights

Why does the server return some IDs as 'not_found' instead of deleting them?

Because those IDs do not exist in the database. The execution_table rows 5 and 6 show that ID 4 was validated as 'Not found' and was not deleted.

What happens if one of the IDs is invalid or malformed?

The server would reject the entire request or return an error for that ID. This is hinted in the concept_flow where validation can lead to an error response if IDs are invalid.

Visual Quiz - 3 Questions

Look at the execution_table, which IDs were successfully deleted?

A [1, 2, 3]

B [2, 3, 4]

C [4]

D None

💡 Hint

Check the 'Delete Result' column in rows 2 to 4.

At which step does the server identify an ID that cannot be deleted?

A Step 3

B Step 6

C Step 5

D Step 7

💡 Hint

Look at the 'Validation Result' column for the step where 'Not found' appears.

If the client sent IDs '1,2,5' and ID 5 does not exist, how would the 'not_found_ids' variable change?

A It would be empty

B It would include 5

C It would include 1 and 2

D It would include all IDs

💡 Hint

Refer to variable_tracker row for 'not_found_ids' and how it tracks missing IDs.

Concept Snapshot

Batch delete pattern:
- Client sends DELETE request with multiple IDs
- Server parses and validates each ID
- Deletes existing items, skips missing ones
- Returns JSON with 'deleted' and 'not_found' lists
- Helps efficiently remove many items in one call

Full Transcript

Batch delete patterns let clients remove many items in one request. The client sends a DELETE request with a list of IDs. The server checks each ID: if it exists, it deletes it; if not, it notes it as not found. The server then sends back a response showing which IDs were deleted and which were missing. This saves time and network calls compared to deleting items one by one.

Practice

1.

What is the main advantage of using batch delete in a REST API?

easy

A. It removes multiple items with a single request, saving time.

B. It automatically backs up data before deletion.

C. It encrypts data during deletion.

D. It requires multiple requests for each item.

Solution

1. Step 1: Understand batch delete purpose

   Batch delete is designed to remove many items at once, not one by one.

2. Step 2: Identify the benefit

   Removing multiple items in one request saves time and reduces server load.

3. Final Answer:

   It removes multiple items with a single request, saving time. -> Option A

4. Quick Check:

   Batch delete = single request for many items [OK]

Hint: Batch delete means one request deletes many items [OK]

Common Mistakes:

• Thinking batch delete backs up data
• Confusing batch delete with encryption
• Assuming batch delete needs multiple requests

2.

Which of the following is the correct HTTP method to perform a batch delete in a REST API?

easy

A. GET

B. POST

C. DELETE

D. PUT

Solution

1. Step 1: Recall HTTP methods for REST

   DELETE method is used to remove resources in REST APIs.

2. Step 2: Match method to batch delete

   Batch delete also uses DELETE but with multiple IDs in body or query.

3. Final Answer:

   DELETE -> Option C

4. Quick Check:

   Batch delete uses DELETE method [OK]

Hint: DELETE method removes resources in REST APIs [OK]

Common Mistakes:

• Using POST instead of DELETE for deletion
• Confusing GET with delete operations
• Using PUT which is for updates

3.

Given this REST API call to delete users with IDs 3, 5, and 7:
DELETE /users?ids=3,5,7
What is the expected behavior?

medium

A. Only user with ID 3 is deleted.

B. Users are deleted one by one with separate requests.

C. The server returns an error because multiple IDs are not allowed.

D. Users with IDs 3, 5, and 7 are deleted in one request.

Solution

1. Step 1: Analyze the query parameter usage

   The query parameter 'ids=3,5,7' lists multiple IDs to delete.

2. Step 2: Understand batch delete behavior

   The API deletes all specified users in one DELETE request.

3. Final Answer:

   Users with IDs 3, 5, and 7 are deleted in one request. -> Option D

4. Quick Check:

   Batch delete with multiple IDs = one request deletes all [OK]

Hint: Multiple IDs in query means batch delete in one request [OK]

Common Mistakes:

• Assuming only first ID is deleted
• Thinking server rejects multiple IDs
• Believing multiple requests are sent automatically

4.

Consider this batch delete request:
DELETE /items
with JSON body:
{ "ids": [10, 20, 30] }
But the server responds with 400 Bad Request. What is the likely cause?

medium

A. The JSON format is incorrect.

B. The server expects IDs in the query string, not body.

C. The DELETE method cannot have a request body.

D. The IDs array is empty.

Solution

1. Step 1: Check DELETE method usage

   Some APIs require IDs in query string, not in request body for DELETE.

2. Step 2: Identify server expectation

   Since server returns 400, it likely expects IDs in query parameters, not JSON body.

3. Final Answer:

   The server expects IDs in the query string, not body. -> Option B

4. Quick Check:

   Server expects IDs in query, not body [OK]

Hint: Check if server wants IDs in query or body for DELETE [OK]

Common Mistakes:

• Assuming DELETE cannot have a body always
• Thinking JSON format is wrong without checking
• Ignoring server API documentation

5.

You want to design a batch delete endpoint for a REST API that deletes multiple products by IDs sent in the request body as JSON. Which approach is best practice?

{
  "ids": [101, 102, 103]
}

Choose the correct method and request format.

hard

A. Use DELETE method with JSON body containing IDs array.

B. Use POST method with JSON body containing IDs array.

C. Use DELETE method with IDs in query string separated by commas.

D. Use GET method with IDs in URL path.

Solution

1. Step 1: Understand REST conventions for delete

   DELETE method is standard for removing resources, including batch deletes.

2. Step 2: Check request body usage

   Modern APIs allow DELETE with JSON body to specify multiple IDs for batch delete.

3. Step 3: Evaluate options

   POST is not for deletion, GET is for retrieval, query string can be limited in length.

4. Final Answer:

   Use DELETE method with JSON body containing IDs array. -> Option A

5. Quick Check:

   DELETE + JSON body for batch delete = best practice [OK]

Hint: Use DELETE with JSON body for multiple IDs batch delete [OK]

Common Mistakes:

• Using POST instead of DELETE for deletion
• Putting IDs in query string risking URL length limits
• Using GET which is not for deletion