Requests Library Deep Dive - 10

Continuing the study of the requests module. Today, I am diving into requests/status_codes.py, a relatively small but useful module that deals with HTTP status codes. It maps numerical HTTP status codes to their textual representations, making the library more human-readable and user-friendly.

Key Concepts in requests/status_codes.py

Purpose

This module provides a dictionary and helper functions for working with HTTP status codes. It makes it easier to understand and handle status codes by providing textual descriptions.

The codes Dictionary

Maps HTTP status codes (e.g., 200, 404) to their textual descriptions (e.g., ok, not_found).

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codes = LookupDict(name='status_codes')

# example entries
_codes = {
    200: 'ok',
    404: 'not_found',
    500: 'internal_server_error',
}

for code, phrase in _codes.items():
    codes[phrase] = code
    codes[code] = [phrase]

Two-way mapping: You can look up either by number or by name:

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from requests.status_codes import codes
codes[200]
# 'ok'
codes['not_found']
# 404

The LookupDict Class

A custom dictionary implmentation that provides case-insensitive lookup for textual representations of status codes.

Key methods:

• __getitem__: Enables standard dictionary access.
• get: Fetches a value while handling missing keys gracefully.

Example:

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class LookupDict(dict):
    def __init__(self, name=None):
        self.name = name

    def __getitem__(self, key):
        try:
            return dict.__getitem__(self, key)
        except KeyError:
            return self.__missing__(key)

    def get(self, key, default=None):
        return self[key] if key in self else default

Convenience in Code

Using this module makes it easier to write clear and readable code when dealing with status codes:

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import requests

response = requests.get('https://example.com')

if response.status_code == requests.codes.ok:
    print("The request was successful!")
elif response.status_code == requests.codes.not_found:
    print("The requested resource was not found.")