REST Principles & HTTP Verbs
REST (Representational State Transfer) is an architectural style for web APIs. It maps CRUD operations to HTTP verbs, uses resource-based URLs with nouns (not verbs), and communicates state through HTTP status codes. Understanding REST constraints - statelessness, uniform interface, resource identification - is essential for building APIs that developers can understand and use predictably.
REST Conventions - URLs, Verbs & Status Codes
# ── REST URL design - nouns, not verbs ─────────────────────────
# ❌ RPC-style (not REST)
GET /getPosts
POST /createPost
POST /updatePost/1
POST /deletePost/1
# ✅ RESTful - resource-based
GET /api/v1/posts → list all posts
POST /api/v1/posts → create a post
GET /api/v1/posts/{id} → get one post
PUT /api/v1/posts/{id} → replace entire post
PATCH /api/v1/posts/{id} → partial update
DELETE /api/v1/posts/{id} → delete post
# Nested resources
GET /api/v1/posts/{id}/comments → comments for a post
POST /api/v1/posts/{id}/comments → add comment to post
DELETE /api/v1/posts/{id}/comments/{cid} → delete a comment
# ── HTTP Status Codes ──────────────────────────────────────────
# 2xx - Success
# 200 OK - GET/PUT/PATCH successful, body returned
# 201 Created - POST successful, new resource created
# 204 No Content - DELETE/PUT successful, no body needed
# 3xx - Redirection
# 301 Moved Permanently - resource URL changed permanently
# 304 Not Modified - cached response still valid (ETag match)
# 4xx - Client errors (caller did something wrong)
# 400 Bad Request - invalid JSON, missing required field
# 401 Unauthorized - no auth token, or token invalid
# 403 Forbidden - authenticated but lacks permission
# 404 Not Found - resource does not exist
# 405 Method Not Allowed - GET only, got POST
# 409 Conflict - duplicate slug, unique constraint violation
# 422 Unprocessable - structurally valid but fails validation
# 429 Too Many Requests - rate limit exceeded
# 5xx - Server errors (your code failed)
# 500 Internal Server Error - unexpected exception
# 502 Bad Gateway - upstream service down
# 503 Service Unavailable - maintenance or overload
# ── JSON:API response envelope ────────────────────────────────
# Standard response structure - consistent across all endpoints:
# {
# "success": true,
# "data": { ... }, ← single resource or array
# "meta": { "total": 42 }, ← optional pagination, counts
# "links": { "next": "..." } ← optional pagination links
# }
#
# Error response:
# {
# "success": false,
# "error": {
# "code": "VALIDATION_ERROR",
# "message": "Validation failed",
# "details": { "title": "Title is required." }
# }
# }Quick Quiz
Tip
Tip
Practice REST Principles HTTP Verbs in small, isolated examples before integrating into larger projects. Breaking concepts into small experiments builds genuine understanding faster than reading alone.
Visual architecture and concepts for REST Principles & HTTP Verbs
Practice Task
Note
Practice Task - (1) Write a working example of REST Principles HTTP Verbs from scratch without looking at notes. (2) Modify it to handle an edge case (empty input, null value, or error state). (3) Share your solution in the Priygop community for feedback.
Common Mistake
Warning
A common mistake with REST Principles HTTP Verbs is skipping edge case testing - empty inputs, null values, and unexpected data types. Always validate boundary conditions to write robust, production-ready php code.