There are two ways to avoid the duplication of attaching the suggested LV hook (which is an alternative of having the handle_params callback of each LiveView assign the current url, which indeed would become very verbose):
- attach on the level of a live_session (look for the
:on_mountoption) - attach using the Phoenix.LiveView.on_mount/1 macro. You can use this method in combination with the
__using__macro that is scaffolded in your typicalMyAppWebmodule, so that it automatically gets added to each LiveView that hasuse MyAppWeb, :live_view. This approach will also minimise repetition.
If you’re using the suggested LV hook, then you shouldn’t need the handle_params hook in any child LiveView (which indeed is not called since it’s not mounted in the router, hence the error). The url will be available as an assign on the socket of the child LiveView (assuming you’re using live_render/3).
I’d be surprised that the LV hook method is more involved than the JavaScript approach. But I must admit that the LV hooks have a steep learning curve. See you on the other side 
