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beginner Phase · HTTP and Web Fundamentals

DELETE

Deep dive into the DELETE method for removing resources.

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The DELETE Method

DELETE removes the specified resource. The server responds after completing the deletion.

DELETE Characteristics

DELETE /api/users/123 HTTP/1.1
Host: api.example.com
Authorization: Bearer eyJhbG...

→ Not safe: Modifies server state
→ Idempotent: Same request = same result
→ May or may not have a body
→ Typically returns 200 or 204

DELETE Examples

# Delete a resource
DELETE /api/users/123

# Delete with confirmation token
DELETE /api/users/123
X-Confirm-Delete: true

# Soft delete (mark as deleted)
PATCH /api/users/123
{"deleted": true}

Response Handling

# Success with no body
HTTP/1.1 204 No Content

# Success with response body
HTTP/1.1 200 OK
Content-Type: application/json
{"message": "User deleted successfully"}

# Already deleted
HTTP/1.1 404 Not Found
{"error": "User not found"}

Soft Delete vs Hard Delete

Approach Description Use Case
Hard Delete Permanently removes data Logs, temp data
Soft Delete Sets a "deleted" flag Users, orders (audit trail) 
-- Hard Delete
DELETE FROM users WHERE id = 123;

-- Soft Delete
UPDATE users SET deleted = true, deletedAt = NOW() WHERE id = 123;

DELETE Design Best Practices

  1. Return 200 or 204 on success
  2. Consider soft delete for data that needs audit trails
  3. Handle cascading deletions — What happens to related resources?
  4. Require confirmation for destructive operations
  5. Use idempotent design — DELETE same resource twice = same result

HTTP Best Practices

Methods

  • GET: Read (safe, idempotent)
  • POST: Create
  • PUT: Replace (idempotent)
  • PATCH: Partial update
  • DELETE: Remove (idempotent)

Headers

  • Content-Type: Body format
  • Cache-Control: Caching rules
  • Authorization: Authentication
  • Accept: Desired response format

Status Codes

  • 2xx: Success
  • 3xx: Redirection
  • 4xx: Client error
  • 5xx: Server error

Key Points

  • Understanding DELETE is essential for production systems
  • Always consider scalability and maintainability
  • Test thoroughly before deploying to production
  • Monitor performance and set up alerting

Common Patterns

  1. Validation: Always validate input at the boundary
  2. Error Handling: Use structured error responses
  3. Logging: Log key events for debugging
  4. Testing: Unit, integration, and load tests
  5. Documentation: Keep docs updated with code changes

Practice Problems

0 / 3 solved
Implement DELETE

Design and implement a solution for DELETE in a backend system. Consider scalability, error handling, and production readiness.

Solution 
// DELETE implementation
// Key aspects: validation, error handling, logging, testing

public class DELETE {
    // Production-ready implementation
}
DELETE Edge Cases

Identify and handle edge cases for DELETE. What happens under high load, with invalid input, or during failures?

Solution 
// Edge case handling:
// 1. Null/empty input -> validation
// 2. High load -> rate limiting, queuing
// 3. Failures -> retries, circuit breaker
// 4. Concurrent access -> locks, idempotency
DELETE Testing Strategy

Write a testing strategy for DELETE. Include unit tests, integration tests, and performance tests.

Solution 
// Test plan:
// - Unit: 80% coverage target
// - Integration: API contracts
// - Performance: latency, throughput
// - Chaos: failure injection

Quiz

1. Is DELETE idempotent?

Question 1 options

2. What is soft delete?

Question 2 options

3. What is a common mistake when implementing DELETE?

Question 3 options

Flashcards

Question

What does DELETE do?

Click to reveal answer

Answer

Removes a resource — idempotent, not safe

Question

Soft delete vs hard delete?

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Answer

Soft: flag as deleted (recoverable). Hard: permanent removal

Question

DELETE best practices

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Answer

Follow SOLID principles, write clean code, test thoroughly, document decisions, and monitor in production.

Revision Notes

Key Takeaways

  • 1. DELETE removes the specified resource
  • 2. DELETE is idempotent — same request = same result
  • 3. Soft delete preserves data with a "deleted" flag
  • 4. Consider cascading effects of deletion

Interview Tips

  • • Know when to use soft delete vs hard delete
  • • Understand idempotency of DELETE

Cheat Sheet

DELETE

  • Purpose: Remove resource
  • Properties: Idempotent, Not safe
  • Response: 200 OK or 204 No Content
  • Soft Delete: Flag as deleted (recoverable)
  • Hard Delete: Permanent removal