Modify request property

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<Response> {
    /**
     * 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 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)

async def on_fetch(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)