Headers and status codes

Introduction to APIs in Python

Chris Ramakers

Engineering Manager

Request and response message anatomy

An example of a request and response message. Request: GET /users/42 with headers. Response: 200 OK with JSON body containing user info.

The start-line

Example of three distinct parts of a request or response message, with the start line highlighted

A server will always include a numeric status code in the response message

Status codes

Status code categories

1XX: Informational responses
2XX: Successful responses
3XX: Redirection messages
4XX: Client error responses
5XX: Server error responses

Frequently used status codes

200: OK
404: Not Found
500: Internal Server Error

¹ For a full list of all response codes you can refer to the MDN page on status-codes via https://developer.mozilla.org/en-US/docs/Web/HTTP/Status

Headers

Example of three distinct parts of a request or response message, with the headers highlighted

key1: Value 1
key2: Value 2

Example: Content negotiation with headers

Example of three distinct parts of a request or response message, with the headers highlighted

Client adds an accept: application/json header to the request
Server responds with a content-type: application/json header

Headers with requests

# Adding headers to a request
response = requests.get(
  'https://api.datacamp.com', 
  headers={'accept':'application/json'}
)

# Reading response headers
response.headers['content-type']

'application/json'

response.headers.get('content-type')

'application/json'

Status codes with requests

# Accessing the status code
response = requests.get('https://api.datacamp.com/users/12')

response.status_code == 200

True

# Looking up status codes using requests.codes
response = requests.get('https://api.datacamp.com/this/is/the/wrong/path')

response.status_code == requests.codes.not_found

True

Let's practice!

Introduction to APIs in Python