Cache POST requests

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 workers import WorkerEntrypoint
from pyodide.ffi import create_proxy
from js import fetch, URL, Headers, Request, caches

class Default(WorkerEntrypoint):
    async def fetch(self, 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)

import { Hono } from "hono";
import { sha256 } from "hono/utils/crypto";

const app = new Hono();

// Middleware for caching POST requests
app.post("*", async (c) => {
	try {
		// Get the request body
		const body = await c.req.raw.clone().text();

		// Hash the request body to use it as part of the cache key
		const hash = await sha256(body);

		// Create the cache URL
		const cacheUrl = new URL(c.req.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: c.req.raw.headers,
			method: "GET",
		});

		const cache = caches.default;

		// Find the cache key in the cache
		let response = await cache.match(cacheKey);

		// If not in cache, fetch response to POST request from origin
		if (!response) {
			response = await fetch(c.req.raw);
			c.executionCtx.waitUntil(cache.put(cacheKey, response.clone()));
		}

		return response;
	} catch (e) {
		return c.text("Error thrown " + e.message, 500);
	}
});

// Handle all other HTTP methods
app.all("*", (c) => {
	return fetch(c.req.raw);
});

export default app;