HTTP Methods Overview

HTTP methods (also called HTTP verbs) define the action to perform on a resource. REST uses these methods to create a uniform interface for all operations.

The Main HTTP Methods

Method	Purpose	Request Body	Response Body	Idempotent	Safe
GET	Retrieve resource	No	Yes	Yes	Yes
POST	Create resource	Yes	Yes	No	No
PUT	Replace resource	Yes	Yes	Yes	No
PATCH	Partial update	Yes	Yes	No*	No
DELETE	Remove resource	No	Optional	Yes	No

*PATCH can be idempotent depending on implementation

GET - Retrieve Resources

GET requests retrieve a resource or collection without modifying anything.

GET /api/users HTTP/1.1
Host: api.example.com
Accept: application/json

Response:

HTTP/1.1 200 OK
Content-Type: application/json

[
  { "id": 1, "name": "Alice" },
  { "id": 2, "name": "Bob" }
]

Key Points:

• Never modifies data (safe)
• Can be cached
• Should be repeatable without side effects
• No request body

POST - Create Resources

POST creates a new resource. The server typically assigns the ID.

POST /api/users HTTP/1.1
Content-Type: application/json

{
  "name": "Charlie",
  "email": "charlie@example.com"
}

Response:

HTTP/1.1 201 Created
Location: /api/users/3
Content-Type: application/json

{
  "id": 3,
  "name": "Charlie",
  "email": "charlie@example.com"
}

Key Points:

• Creates new resources
• Returns 201 Created on success
• Include Location header with new resource URL
• Not idempotent (calling twice creates two resources)

PUT - Replace Resources

PUT replaces an entire resource. If it doesn't exist, it may create it.

PUT /api/users/3 HTTP/1.1
Content-Type: application/json

{
  "name": "Charlie Updated",
  "email": "charlie.new@example.com",
  "role": "admin"
}

Response:

HTTP/1.1 200 OK
Content-Type: application/json

{
  "id": 3,
  "name": "Charlie Updated",
  "email": "charlie.new@example.com",
  "role": "admin"
}

Key Points:

• Replaces the entire resource
• Include all fields (missing fields may be set to null)
• Idempotent (calling twice has same result as calling once)
• Client specifies the resource ID

PATCH - Partial Updates

PATCH applies partial modifications to a resource.

PATCH /api/users/3 HTTP/1.1
Content-Type: application/json

{
  "role": "moderator"
}

Response:

HTTP/1.1 200 OK
Content-Type: application/json

{
  "id": 3,
  "name": "Charlie Updated",
  "email": "charlie.new@example.com",
  "role": "moderator"
}

Key Points:

• Only send fields that need updating
• Other fields remain unchanged
• More efficient than PUT for small changes

DELETE - Remove Resources

DELETE removes a resource.

DELETE /api/users/3 HTTP/1.1

Response:

HTTP/1.1 204 No Content

Key Points:

• Idempotent (deleting twice returns same result)
• Typically returns 204 No Content
• Can return 200 OK with deleted resource info

Exercise: Choose the Right Method

Less Common Methods

HEAD

Like GET but returns only headers, no body. Useful for checking if a resource exists.

HEAD /api/users/123 HTTP/1.1

OPTIONS

Returns allowed methods and CORS information.

OPTIONS /api/users HTTP/1.1

HTTP/1.1 200 OK
Allow: GET, POST, HEAD, OPTIONS

Summary

Method	Use When...
GET	You want to retrieve data without changing anything
POST	You're creating a new resource
PUT	You're replacing an entire resource
PATCH	You're updating part of a resource
DELETE	You're removing a resource

Choosing the right HTTP method is fundamental to RESTful design. In the next lesson, we'll see how these methods map to CRUD operations.