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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);
}
},
};

const handler: ExportedHandler = {
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);
}
},
};
export default handler;