Hello everyone,

  I am trying to implement offline functionality for the Odoo Sales app using a custom service worker. I am facing an issue where the

  service worker fails to fetch the list of assets to cache during its install event.

  Here's what I have done so far:

1.    Created a custom Odoo module (pwa_sales_offline) that depends on web, sale_management, and stock.
2.    Created a custom service worker at pwa_sales_offline/static/src/service_worker.js.
3. Overridden the default service worker by creating a controller that inherits from odoo.addons.web.controllers.webmanifest.WebManifest and overrides the _get_service_worker_content method to serve my custom file.
4. Created a controller to get the list of assets. This controller calls request.env['ir.qweb']._get_asset_nodes('web.assets_backend', True, True, False, False, request.env.context) and returns the list of asset URLs as a JSON response.
5. The service worker's install event fetches this list of assets and tries to cache them using cache.addAll().

  The Problem:

  ​The fetch call within the service worker's install event fails with the error: Uncaught (in promise) TypeError: Failed to fetch.

  What I have tried:

   * I have verified that the controller that returns the list of assets is working correctly by opening its URL (/pwa_sales_offline/assets)

     directly in the browser. It successfully returns a JSON array of asset URLs.

   * I have tried changing the auth of the controller to public.

   * I have tried changing the type of the controller to both http and json.

   * I have added a check in the service worker's fetch event to prevent it from intercepting its own requests to the assets endpoint.

  The Code:

  Here is the relevant code:

import logging
import json
from odoo import http
from odoo.http import request
from odoo.tools import file_open
from odoo.addons.web.controllers.webmanifest import WebManifest

_logger = logging.getLogger(__name__)

class PwaSalesOfflineWebManifest(WebManifest):
    def _get_service_worker_content(self):
        _logger.info("Serving custom service worker")
        with file_open('pwa_sales_offline/static/src/service_worker.js') as f:
            return f.read()

    @http.route('/pwa_sales_offline/assets', type='http', auth='public', methods=['GET'], csrf=False)
    def get_assets(self):
        _logger.info("Getting assets for PWA")
        qweb = request.env['ir.qweb']
        nodes = qweb._get_asset_nodes('web.assets_backend', True, True, False, False, request.env.context)
        files = []
        for node in nodes:
            if len(node) == 2:
                tag, attrs = node
                if 'href' in attrs:
                    files.append(attrs['href'])
                elif 'src' in attrs:
                    files.append(attrs['src'])
            elif len(node) == 3:
                tag, attrs, content = node
                if 'href' in attrs:
                    files.append(attrs['href'])
                elif 'src' in attrs:
                    files.append(attrs['src'])
        _logger.info("Found %d assets", len(files))
        return request.make_json_response(files)

const STATIC_CACHE_NAME = 'odoo-sales-offline-static-cache';

self.addEventListener('install', (event) => {
    console.log('Custom Service Worker: Installed!');
    event.waitUntil(
        fetch('/pwa_sales_offline/assets').then((response) => {
            return response.json();
        }).then((files) => {
            return caches.open(STATIC_CACHE_NAME).then((cache) => {
                return cache.addAll(files);
            });
        })
    );
});

self.addEventListener('fetch', (event) => {
    console.log('Custom Service Worker: Fetching', event.request.url);
    const url = new URL(event.request.url);

    if (url.pathname === '/pwa_sales_offline/assets') {
        return;
    }

    // Serve static assets from cache
    if (url.origin === location.origin) {
        event.respondWith(
            caches.match(event.request).then((response) => {
                return response || fetch(event.request);
            })
        );
        return;
    }

    // Cache data
    const DATA_CACHE_NAME = 'odoo-sales-offline-data-cache';
    if (url.pathname === '/web/dataset/search_read') {
        event.respondWith(
            fetch(event.request.clone()).then((response) => {
                if (response.status === 200) {
                    event.request.clone().json().then((payload) => {
                        if (payload.params && (payload.params.model === 'res.partner' || payload.params.model === 'product.product')) {
                            const cacheRequest = event.request.clone();
                            const cacheResponse = response.clone();
                            caches.open(DATA_CACHE_NAME).then((cache) => {
                                cache.put(cacheRequest, cacheResponse);
                            });
                        }
                    });
                }
                return response;
            }).catch(() => {
                return caches.match(event.request);
            })
        );
    }
});

  ​I would appreciate any help or suggestions on how to solve this issue. Is there a better way to get the asset list from within the

  service worker? Or is there something I'm missing about how fetch works in this context?

  Thank you