Hello All,
I found this thread while trying to get params for a “router” liveview.
This has changed very recently (with version 0.6.0) so I put this as a reminder for future readers.

Now it is possible to get params (url ids + querystrings) directly from mount/3 which now accepts params as a first argument, ex :

def mount(%{"id" => id, "token" => token} = params, session, socket) do
....

I think this is the correct way of handling it as of today

Cheers,
Sébastien.

You can only receive path params via the handle_params/3 callback, and handle_params is only invoked for the root LV. If you are trying to get path params to a child, you need to retrieve them from the root and pass them down to the children via assigns in the parent

Useful clarification recently added by Jose when deciding whether to use mount or handle_params

Note the parameters given to c:handle_params/3 are the same as the ones given
to c:mount/3. So how do you decide which callback to use to load data?
Generally speaking, data should always be loaded on c:mount/3, since c:mount/3
is invoked once per LiveView life-cycle. Only the params you expect to be changed
via live_patch/2 or push_patch/2 must be loaded on c:handle_params/3.

https://github.com/phoenixframework/phoenix_live_view/commit/34424f37c3be388414d180536f30b208d06602bd