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Examples

Cloudflare has a wide range of Python examples in the Workers Example gallery.

In addition to those examples, consider the following ones that illustrate Python-specific behavior.

Parse an incoming request URL

from js import Response
from urllib.parse import urlparse, parse_qs
async def on_fetch(request, env):
# Parse the incoming request URL
url = urlparse(request.url)
# Parse the query parameters into a Python dictionary
params = parse_qs(url.query)
if "name" in params:
greeting = "Hello there, {name}".format(name=params["name"][0])
return Response.new(greeting)
if url.path == "/favicon.ico":
return Response.new("")
return Response.new("Hello world!")

Parse JSON from the incoming request

from js import Response
async def on_fetch(request):
name = (await request.json()).name
return Response.new("Hello, {name}".format(name=name))

Emit logs from your Python Worker

# To use the JavaScript console APIs
from js import console, Response
# To use the native Python logging
import logging
async def on_fetch(request):
# Use the console APIs from JavaScript
# https://developer.mozilla.org/en-US/docs/Web/API/console
console.log("console.log from Python!")
# Alternatively, use the native Python logger
logger = logging.getLogger(__name__)
# The default level is warning. We can change that to info.
logging.basicConfig(level=logging.INFO)
logger.error("error from Python!")
logger.info("info log from Python!")
# Or just use print()
print("print() from Python!")
return Response.new("We're testing logging!")

Publish to a Queue

from js import Response, Object
from pyodide.ffi import to_js as _to_js
# to_js converts between Python dictionaries and JavaScript Objects
def to_js(obj):
return _to_js(obj, dict_converter=Object.fromEntries)
async def on_fetch(request, env):
# Bindings are available on the 'env' parameter
# https://developers.cloudflare.com/queues/
# The default contentType is "json"
# We can also pass plain text strings
await env.QUEUE.send("hello", contentType="text")
# Send a JSON payload
await env.QUEUE.send(to_js({"hello": "world"}))
# Return a response
return Response.json(to_js({"write": "success"}))

Query a D1 Database

from js import Response
async def on_fetch(request, env):
results = await env.DB.prepare("PRAGMA table_list").all()
# Return a JSON response
return Response.json(results)

Refer to Query D1 from Python Workers for a more in-depth tutorial that covers how to create a new D1 database and configure bindings to D1.

Next steps