You need to pull the user_token from the session and fetch the user in the same way the plug pipeline does. You can make use of assign_new to avoid fetching on the HTTP request, but you need to fallback to fetching on the connected mount, using the same mechanism that the plug pipeline does:

      def mount(_params, %{"user_token" => user_token}, socket) do
        {:ok, 
          socket 
          |> ...
          |> assign_new(:current_user, fn -> 
            Accounts.get_user_by_session_token(user_token)
         end)}
      end

To avoid duplication in your LVs, you could pull this out into an assign_defaults function that you write to wire up common assigns, like current_user. Make sense?

Hello,
I wanted to achieve the same kind of behaviour and be able to access to the current_user in my live view assigns.
The best would be able to assign the current_user to the socket assign, but it doesn’t seems to be possible.
The only way I found to achieve this is to inject a mount function, in live :

  def live do
    quote do
      use BrandManagerWeb.LoadUser
      use Phoenix.LiveView, layout: {BrandManagerWeb.LayoutView, "app.html"}
      alias BrandManagerWeb.Router.Helpers, as: Routes
    end
  end

defmodule BrandManagerWeb.LoadUser do
  alias Core.Accounts
  alias Phoenix.LiveView

  defmacro __using__(_opts) do
    quote do
      def mount(params, %{"user_id" => user_id} = session, socket) do
        session = Map.delete(session, "user_id")

        socket =
          LiveView.assign_new(socket, :current_user, fn ->
            manager_id && Accounts.get_user(user_id)
          end)

        mount(params, session, socket)
      end
    end
  end
end

It is working, but it is kind of a hack

Is there a better way to achieve this ?
Thanks in advance!

That’s now the default behaviour (all the session is passed and you don’t need to specify the keys):

When a LiveView is rendered, all of the data currently stored in the connection session (see Plug.Conn.get_session/1 ) will be given to the LiveView.

It is also possible to pass additional session information to the LiveView through a session parameter:

# In the router
live "/thermostat", ThermostatLive, session: %{"extra_token" => "foo"}

# In a view
<%= live_render(@conn, AppWeb.ThermostatLive, session: %{"extra_token" => "foo"}) %>

Notice the :session uses string keys as a reminder that session data is serialized and sent to the client. So you should always keep the data in the session to a minimum. I.e. instead of storing a User struct, you should store the “user_id” and load the User when the LiveView mounts.

You could always add a cache for getting the user with a low refresh ttl value.