documentation/tutorials/use-ash-authentication-with-liveview.md

# Setting up your routes

A built in live session wrapper is provided that will set the user assigns for you. To use it, wrap your live routes like so:

```elixir
ash_authentication_live_session :session_name do
  live "/route", ProjectLive.Index, :index
end
```

There are two problems with the above, however.

1. If there is no user present, it will not set `current_user: nil`.
2. You may want a way to require that a user is present for some routes, and not for others.

## Authentication helper

To accomplish this, we use standard Phoenix [`on_mount` hooks](https://hexdocs.pm/phoenix_live_view/Phoenix.LiveView.html#on_mount/1-examples). Lets define a hook that gives us three potential behaviors, one for optionally having a user signed in, one for requiring a signed in user, and one for requiring that there is no signed in user.


```elixir
# lib/my_app_web/live_user_auth.ex
defmodule MyAppWeb.LiveUserAuth do
  @moduledoc """
  Helpers for authenticating users in LiveViews.
  """

  import Phoenix.Component
  use MyAppWeb, :verified_routes

  def on_mount(:live_user_optional, _params, _session, socket) do
    if socket.assigns[:current_user] do
      {:cont, socket}
    else
      {:cont, assign(socket, :current_user, nil)}
    end
  end

  def on_mount(:live_user_required, _params, _session, socket) do
    if socket.assigns[:current_user] do
      {:cont, socket}
    else
      {:halt, Phoenix.LiveView.redirect(socket, to: ~p"/sign-in")}
    end
  end

  def on_mount(:live_no_user, _params, _session, socket) do
    if socket.assigns[:current_user] do
      {:halt, Phoenix.LiveView.redirect(socket, to: ~p"/")}
    else
      {:cont, assign(socket, :current_user, nil)}
    end
  end
end
```

And we can use this as follows:

```elixir
# lib/my_app_web/router.ex
  # ...
  scope "/", MyAppWeb do
    # ...
    ash_authentication_live_session :authentication_required,
      on_mount: {MyAppWeb.LiveUserAuth, :live_user_required} do
      live "/protected_route", ProjectLive.Index, :index
    end

    ash_authentication_live_session :authentication_optional,
      on_mount: {MyAppWeb.LiveUserAuth, :live_user_optional} do
      live "/", ProjectLive.Index, :index
    end
  end
  # ...
```

You can also use this to prevent users from visiting the auto generated `sign_in` route:

```elixir
sign_in_route(on_mount: [{MyAppWeb.LiveUserAuth, :live_no_user}])
```