It is important to use safe when you build html from the outside source, like inputs. Future versions of Drab will take safe directly, so you’ll not have to add safe_to_string/1.

Yes and no. I did the steps (edited below to be more accurate) and I get the same error. However - this time I did rm -rf _build and then when I restarted the server it recompiled with no error. That works for me!

That said - please let me re-document my steps as I did not record them 100% correctly the first time. I am using Phoenix 1.4, Elixir 1.7.4, Erlang/OTP 21.

1. mix phx.new my_app --no-ecto
2. add {:drab, "~0.10.1"} to mix.exs
3. mix deps.get
4. mix drab.install
5. mix drab.gen.commander Page
6. add config: drab, :presence, true to config.exs
7. add Drab.Presence to my supervision tree in lib/my_app/application.ex
8. add import Drab.Presence to page_commander.ex
9. note that config: Drab, MyAppWeb.Endpoint, otp_app: my_app is in config.exs
10. run mix phx.server

I deviated from the instructions in the docs in two respects:

1. The docs say to modify the supervision tree in lib/my_app_web.ex; I’m assuming that where the supervision tree was specified in an older version of Phoenix?

2. The docs say to make sure that config: Drab, MyAppWeb.Endpoint, otp_app: my_app_web is set, not my_app, which is what was inserted into my file by the generator. I admit I don’t really understand what that is doing. I did modify it to my_app_web and get the same error, for what that is worth.

Do

import Phoenix.HTML

in the commander, or just call Phoenix.HTML.safe_to_string directly.

Tried to call module.function, that gave page_commander.ex:14: undefined function sigil_E/2.
Now,
page_commander.ex:16: undefined function message/0

it’s the 3rd line in

  defhandler update_chat(socket, sender) do
    nick = get_store(socket, :nickname, "Anonymous")
    html = ~E"<strong><%= nick %>:</strong> <%= message %><br>" |> safe_to_string()

Yes, I made a mistake when copying the code to the html, will be added soon.
message = sender["value"] is correct.