Phoenix presence list isn't showing last person that joined as online

Phoenix Forum Questions / Help
,
1

I’m tracking online users with :after_join callback and after pushing new state I expect to see list of online users in this callback but map object is empty in this process, on the other hand, while creating new connection i see the previous connection in the list of online users.

What could be wrong? Is this expectation correct?

2

Hello and welcome,

How does your after join looks like? I have one like this…

  def handle_info(:after_join, socket) do
    user = socket.assigns.user
    {:ok, _} = Presence.track(socket, user.id, %{
      username: user.name,
      online_at: System.system_time(:second)
    })
    push(socket, "presence_state", Presence.list(socket))
    {:noreply, socket}
  end

In the Phoenix example the push state is before the presence track. Thus there is a presence state push (without user), then a presence diff (with user)…

I put the presence_state after presence track because the first presence state will include user and there will be no presence diff push.

I would advise to put some code to help us understand your question, and thus have better answers :slight_smile:

3

Presence list is correct on front end side. But i need to get presence list after tracking.
For Example:

  def handle_info(:after_join, socket) do
    user = socket.assigns.user
    {:ok, _} = Presence.track(socket, user.id, %{
      username: user.name,
      online_at: System.system_time(:second)
    })
    push(socket, "presence_state", Presence.list(socket))

    IO.inspect(Presence.list(socket))
    # Map is empty

    {:noreply, socket}
  end
4

Adding this line and I get…

IO.inspect Presence.list(socket)

My logs are OK.

%{
  "1" => %{
    metas: [
      %{online_at: 1566756304, phx_ref: "VWfwpRtjkho=", username: "admin"}
    ]
  },
  "2" => %{
    metas: [%{online_at: 1566755805, phx_ref: "Zgt30Q+VRME=", username: "kiki"}]
  }
}
5

Would you close all the browser tabs that includes Phoenix socket and stop Phoenix server then check the logs?

6

Still OK. Please show some of your code…

7

Forget that send the sample code but problem solved and i expected to see online user after connection of user closed which was wrong thought :smile:

8

I have this same problem. This comes from the book written by Chris McCord. I tried your suggestion of putting push after Presence.track yet to no avail.

My code is here on Github

9

Did you solve this? I too am having the same problem. Blank presence list, even though the Logger shows it isn’t blank

10

OK, scrap that. I wasn’t passing in the correct var to the list function.

This works for me:

Presence.list(socket)
11

I didn’t solve it. I’ll try your solution. Thanks for posting it.