Can't Override request.url in beforeRequest hook

[kevbook]

Use case, we need to check and append token search-param because our some of our vendors use search parameters instead of headers. But request.url only has a getter.

[sindresorhus]

You can make a new request:

return new Request(newURL, request);

[kevbook]

Something like this?

import type { BeforeRequestHook } from 'ky';

/**
 * Round-robin helper to rotate headers or search params (e.g. for API keys)
 *
 * Usage:
 * const client = await ky.create(url, {
 *   hooks: { beforeRequest: [
 *     roundRobin('headers', [
 *       { 'key': 'API_KEY_1', 'client-id': 'CLIENT_ID_1' ...},
 *       { 'key': 'API_KEY_2', 'client-id': 'CLIENT_ID_2' ...},
 *       { 'key': 'API_KEY_3', 'client-id': 'CLIENT_ID_3' ...}
 *     ])
 *   ]}
 * });
 */
export const roundRobin = function (
  paramType: 'headers' | 'searchParams',
  requestParamsArr: Record<string, string>[]
) {
  // Validate that each object has non-empty string values
  requestParamsArr.forEach(function (params, index) {
    if (
      Object.entries(params).some(function ([_key, value]) {
        return typeof value !== 'string' || value.trim() === '';
      })
    ) {
      throw new Error(`Request params at index ${index} contains non-string value`);
    }
  });

  const requestParamsLen = requestParamsArr.length;
  let state = 0; // Keeps track of which header set to use next

  return function (request) {
    // Get the current set of search params based on the state
    const currentParams = requestParamsArr[state] as Record<string, string>;

    // Apply each header in the current set
    if (paramType === 'headers') {
      for (const [key, value] of Object.entries(currentParams)) {
        request.headers.set(key, value);
      }

      // Move to the next header set in the array, loop back when at the end
      state = (state + 1) % requestParamsLen;
    } else if (paramType === 'searchParams') {
      const url = new URL(request.url);
      for (const [key, value] of Object.entries(currentParams)) {
        url.searchParams.set(key, value);
      }
      // Move to the next header set in the array, loop back when at the end
      state = (state + 1) % requestParamsLen;
      // console.log('===================', url);
      new Request(url, request);
    }
  } satisfies BeforeRequestHook;
};

[theoephraim]

Modifying the URL in some kind of hook is definitely needed quite often. Ideally one could mess with searchParams and urlPrefix too, because if you are already using them elsewhere, it will make things a little simpler. It would probably be fine if it was a different hook if that made things easier.

Returning a new request seems to work but definitely feels a bit more awkward then it could.

Also mentioned here - #431

[sholladay]

We should make it so that you can return a URL instance. I suppose we could treat a string as a URL, too.