Requests Basics

fetching: requests vs pyfetch

In a regular Python script you use the requests library:

import requests

response = requests.get("https://api.example.com/data")
print(response.status_code)
print(response.json())

This site runs Python in a browser Web Worker via Pyodide, so the network goes through the browser's fetch instead. The Pyodide-native wrapper is pyodide.http.pyfetch:

from pyodide.http import pyfetch

response = await pyfetch("https://jsonplaceholder.typicode.com/users/1")
print(response.status)
data = await response.json()
print(data)

Same shape, two differences worth knowing:

• It's async. You must await both the fetch and .json().
• It runs from the browser, so the target API has to send CORS headers. Sites that don't, you can't reach directly.

When you ship a real script you'll write requests.get. The patterns translate.

status, json, errors

response = await pyfetch(url)

response.status     # 200, 404, 500 ...
response.ok         # True if status < 400
await response.string()  # raw text
await response.json()    # parsed JSON

Handle failures explicitly. Network errors raise; bad status codes don't:

try:
    response = await pyfetch(url)
    if response.status >= 400:
        print(f"HTTP {response.status}")
    else:
        data = await response.json()
except Exception as e:
    print(f"request failed: {e}")

query params

pyfetch doesn't have a params= keyword like requests does. Build the query string yourself:

from urllib.parse import urlencode

params = {"userId": 1}
url = f"https://jsonplaceholder.typicode.com/posts?{urlencode(params)}"
response = await pyfetch(url)
posts = await response.json()
print(f"{len(posts)} posts for user 1")

public test API

Examples below hit jsonplaceholder.typicode.com. It's a free, CORS-friendly fake API with users, posts, comments, todos. Real HTTP, real JSON, no auth required. Good for practice without spinning up your own backend.