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Cache POST requests

Cache POST requests using the Cache API.
export default {
async fetch(request, env, ctx) {
async function sha256(message) {
// encode as UTF-8
const msgBuffer = await new TextEncoder().encode(message);
// hash the message
const hashBuffer = await crypto.subtle.digest("SHA-256", msgBuffer);
// convert bytes to hex string
return [...new Uint8Array(hashBuffer)]
.map((b) => b.toString(16).padStart(2, "0"))
.join("");
}
try {
if (request.method.toUpperCase() === "POST") {
const body = await request.clone().text();
// Hash the request body to use it as a part of the cache key
const hash = await sha256(body);
const cacheUrl = new URL(request.url);
// Store the URL in cache by prepending the body's hash
cacheUrl.pathname = "/posts" + cacheUrl.pathname + hash;
// Convert to a GET to be able to cache
const cacheKey = new Request(cacheUrl.toString(), {
headers: request.headers,
method: "GET",
});
const cache = caches.default;
// Find the cache key in the cache
let response = await cache.match(cacheKey);
// Otherwise, fetch response to POST request from origin
if (!response) {
response = await fetch(request);
ctx.waitUntil(cache.put(cacheKey, response.clone()));
}
return response;
}
return fetch(request);
} catch (e) {
return new Response("Error thrown " + e.message);
}
},
};
interface Env {}
export default {
async fetch(request, env, ctx): Promise<Response> {
async function sha256(message) {
// encode as UTF-8
const msgBuffer = await new TextEncoder().encode(message);
// hash the message
const hashBuffer = await crypto.subtle.digest("SHA-256", msgBuffer);
// convert bytes to hex string
return [...new Uint8Array(hashBuffer)]
.map((b) => b.toString(16).padStart(2, "0"))
.join("");
}
try {
if (request.method.toUpperCase() === "POST") {
const body = await request.clone().text();
// Hash the request body to use it as a part of the cache key
const hash = await sha256(body);
const cacheUrl = new URL(request.url);
// Store the URL in cache by prepending the body's hash
cacheUrl.pathname = "/posts" + cacheUrl.pathname + hash;
// Convert to a GET to be able to cache
const cacheKey = new Request(cacheUrl.toString(), {
headers: request.headers,
method: "GET",
});
const cache = caches.default;
// Find the cache key in the cache
let response = await cache.match(cacheKey);
// Otherwise, fetch response to POST request from origin
if (!response) {
response = await fetch(request);
ctx.waitUntil(cache.put(cacheKey, response.clone()));
}
return response;
}
return fetch(request);
} catch (e) {
return new Response("Error thrown " + e.message);
}
},
} satisfies ExportedHandler<Env>;
import hashlib
from pyodide.ffi import create_proxy
from js import fetch, URL, Headers, Request, caches
async def on_fetch(request, _, ctx):
if 'POST' in request.method:
# Hash the request body to use it as a part of the cache key
body = await request.clone().text()
body_hash = hashlib.sha256(body.encode('UTF-8')).hexdigest()
# Store the URL in cache by prepending the body's hash
cache_url = URL.new(request.url)
cache_url.pathname = "/posts" + cache_url.pathname + body_hash
# Convert to a GET to be able to cache
headers = Headers.new(dict(request.headers).items())
cache_key = Request.new(cache_url.toString(), method='GET', headers=headers)
# Find the cache key in the cache
cache = caches.default
response = await cache.match(cache_key)
# Otherwise, fetch response to POST request from origin
if response is None:
response = await fetch(request)
ctx.waitUntil(create_proxy(cache.put(cache_key, response.clone())))
return response
return fetch(request)