--- title: Modify request property description: Create a modified request with edited properties based off of an incoming request. image: https://developers.cloudflare.com/dev-products-preview.png --- > Documentation Index > Fetch the complete documentation index at: https://developers.cloudflare.com/workers/llms.txt > Use this file to discover all available pages before exploring further. [Skip to content](#%5Ftop) ### Tags [ Middleware ](https://developers.cloudflare.com/search/?tags=Middleware)[ Headers ](https://developers.cloudflare.com/search/?tags=Headers)[ JavaScript ](https://developers.cloudflare.com/search/?tags=JavaScript)[ TypeScript ](https://developers.cloudflare.com/search/?tags=TypeScript)[ Python ](https://developers.cloudflare.com/search/?tags=Python) # Modify request property **Last reviewed:** over 5 years ago Create a modified request with edited properties based off of an incoming request. If you want to get started quickly, click on the button below. [![Deploy to Cloudflare](https://deploy.workers.cloudflare.com/button)](https://deploy.workers.cloudflare.com/?url=https://github.com/cloudflare/docs-examples/tree/main/workers/modify-request-property) This creates a repository in your GitHub account and deploys the application to Cloudflare Workers. * [ JavaScript ](#tab-panel-9321) * [ TypeScript ](#tab-panel-9322) * [ Python ](#tab-panel-9323) * [ Hono ](#tab-panel-9324) JavaScript ``` export default { async fetch(request) { /** * Example someHost is set up to return raw JSON * @param {string} someUrl the URL to send the request to, since we are setting hostname too only path is applied * @param {string} someHost the host the request will resolve too */ const someHost = "example.com"; const someUrl = "https://foo.example.com/api.js"; /** * The best practice is to only assign new RequestInit properties * on the request object using either a method or the constructor */ const newRequestInit = { // Change method method: "POST", // Change body body: JSON.stringify({ bar: "foo" }), // Change the redirect mode. redirect: "follow", // Change headers, note this method will erase existing headers headers: { "Content-Type": "application/json", }, // Change a Cloudflare feature on the outbound response cf: { apps: false }, }; // Change just the host const url = new URL(someUrl); url.hostname = someHost; // Best practice is to always use the original request to construct the new request // to clone all the attributes. Applying the URL also requires a constructor // since once a Request has been constructed, its URL is immutable. const newRequest = new Request( url.toString(), new Request(request, newRequestInit), ); // Set headers using method newRequest.headers.set("X-Example", "bar"); newRequest.headers.set("Content-Type", "application/json"); try { return await fetch(newRequest); } catch (e) { return new Response(JSON.stringify({ error: e.message }), { status: 500, }); } }, }; ``` TypeScript ``` export default { async fetch(request): Promise { /** * Example someHost is set up to return raw JSON * @param {string} someUrl the URL to send the request to, since we are setting hostname too only path is applied * @param {string} someHost the host the request will resolve too */ const someHost = "example.com"; const someUrl = "https://foo.example.com/api.js"; /** * The best practice is to only assign new RequestInit properties * on the request object using either a method or the constructor */ const newRequestInit = { // Change method method: "POST", // Change body body: JSON.stringify({ bar: "foo" }), // Change the redirect mode. redirect: "follow", // Change headers, note this method will erase existing headers headers: { "Content-Type": "application/json", }, // Change a Cloudflare feature on the outbound response cf: { apps: false }, }; // Change just the host const url = new URL(someUrl); url.hostname = someHost; // Best practice is to always use the original request to construct the new request // to clone all the attributes. Applying the URL also requires a constructor // since once a Request has been constructed, its URL is immutable. const newRequest = new Request( url.toString(), new Request(request, newRequestInit), ); // Set headers using method newRequest.headers.set("X-Example", "bar"); newRequest.headers.set("Content-Type", "application/json"); try { return await fetch(newRequest); } catch (e) { return new Response(JSON.stringify({ error: e.message }), { status: 500, }); } }, } satisfies ExportedHandler; ``` Python ``` import json from workers import WorkerEntrypoint from pyodide.ffi import to_js as _to_js from js import Object, URL, Request, fetch, Response def to_js(obj): return _to_js(obj, dict_converter=Object.fromEntries) class Default(WorkerEntrypoint): async def fetch(self, request): some_host = "example.com" some_url = "https://foo.example.com/api.js" # The best practice is to only assign new_request_init properties # on the request object using either a method or the constructor new_request_init = { "method": "POST", # Change method "body": json.dumps({ "bar": "foo" }), # Change body "redirect": "follow", # Change the redirect mode # Change headers, note this method will erase existing headers "headers": { "Content-Type": "application/json", }, # Change a Cloudflare feature on the outbound response "cf": { "apps": False }, } # Change just the host url = URL.new(some_url) url.hostname = some_host # Best practice is to always use the original request to construct the new request # to clone all the attributes. Applying the URL also requires a constructor # since once a Request has been constructed, its URL is immutable. org_request = Request.new(request, new_request_init) new_request = Request.new(url.toString(),org_request) new_request.headers["X-Example"] = "bar" new_request.headers["Content-Type"] = "application/json" try: return await fetch(new_request) except Exception as e: return Response.new({"error": str(e)}, status=500) ``` TypeScript ``` import { Hono } from "hono"; const app = new Hono(); app.all("*", async (c) => { /** * Example someHost is set up to return raw JSON */ const someHost = "example.com"; const someUrl = "https://foo.example.com/api.js"; // Create a URL object to modify the hostname const url = new URL(someUrl); url.hostname = someHost; // Create a new request // First create a clone of the original request with the new properties const requestClone = new Request(c.req.raw, { // Change method method: "POST", // Change body body: JSON.stringify({ bar: "foo" }), // Change the redirect mode redirect: "follow" as RequestRedirect, // Change headers, note this method will erase existing headers headers: { "Content-Type": "application/json", "X-Example": "bar", }, // Change a Cloudflare feature on the outbound response cf: { apps: false }, }); // Then create a new request with the modified URL const newRequest = new Request(url.toString(), requestClone); // Send the modified request const response = await fetch(newRequest); // Return the response return response; }); // Handle errors app.onError((err, c) => { return err.getResponse(); }); export default app; ``` ```json {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/directory/","name":"Directory"}},{"@type":"ListItem","position":2,"item":{"@id":"/workers/","name":"Workers"}},{"@type":"ListItem","position":3,"item":{"@id":"/workers/examples/","name":"Examples"}},{"@type":"ListItem","position":4,"item":{"@id":"/workers/examples/modify-request-property/","name":"Modify request property"}}]} ```