Always get that my join/3 function is undefined(join crash). What am I missing?

Deathslice246

I have these two channels: UserChannel and PrivateChannel. UserChannel is the user’s own lobby and an example of joining that channel is user:3 where 3 is the user’s id. An example of joining private channel is private:3:23 where 3 is the id of the first user and 23 is the id of the second user.

The series of events that a user would take is as follows: In the client side when the user login, I create the socket and send in the user’s id as the socket’s param and try to connect to the UserChannel; this occurs successfully. When the user wants to initiate a private chat, they search by name and a series of profiles appear. Once they click on it, a function called startPrivateChat fires and calls the connectToPrivateChat defined in my chat.js. What happens is that I get a join crash because my join/3 function in App.PrivateChannel is undefined.

Now in the phoenix documentation and from multiple other sources, they say that all I need is one socket and I can use that socket to multiplex to different channels. So what I did is create a chat.js service that references things like the socket, the two channels(this.user_channel and this.private_channel) and another methods like connectToSocket, connectToUserChannel, connectToPrivateChannel etc. So why is this happening and what exactly am I doing wrong?

P.S - I’m using Phoenix 1.2 and Elixir 1.6.5

user_socket.ex

defmodule AppChat.UserSocket do
 use Phoenix.Socket

 channel "user:*", AppChat.UserChannel
 channel "private:*", AppChat.PrivateChannel

 transport :websocket, Phoenix.Transports.WebSocket

 def connect(%{ "user_id" => id }, socket) do
   current_user = AppChat.Repo.get(AppChat.User, String.to_integer(id))
   {:ok, assign(socket, :current_user, current_user)}
 end

 def id(socket), do: "user_socket:#{socket.assigns.current_user.id}"
end

user_channel.ex

defmodule AppChat.UserChannel do
  use AppChat.Web, :channel
  require Logger

  def join("user:" <> user_id, _payload, socket) do
    if socket.assigns.current_user.id == String.to_integer(user_id) do
      {:ok, socket}
    else
      {:error, %{reason: "unauthorized"}}
    end
  end
end

private_channel.ex

defmodule AppChat.PrivateChannel do
  use AppChat.Web, :channel
  require Logger

  def join("private:" <> users_string, _payload, socket) do
    if users_string |> String.split(":") |> Enum.member?(socket.assigns.current_user.id) do
	{:ok, %{}, socket}
    else
	{:error, %{reason: "unauthorized"}}
    end
  end
end

22 comments

/phoenix #channel #join3

0 3291 22

2018-06-21 16:51:30 UTC

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kokolegorille

This will never be true, because id is an Int, while the list contains Strings.

It would be nice to see the join crash error log. I guess it might be js crashing, not channels crashing.

Post #1

Deathslice246

Yes, you are right. But even after correcting it(to_string(socket.assigns.current_user.id)), I still get the same error. Here is what the error log says.

[info] JOIN private:3:3 to AppChat.PrivateChannel
  Transport:  Phoenix.Transports.WebSocket
  Parameters: %{}
[error] an exception was raised:
    ** (UndefinedFunctionError) function AppChat.PrivateChannel.join/3 is undefined (module AppChat.PrivateChannel is not available)
        AppChat.PrivateChannel.join("private:3:3", %{}, %Phoenix.Socket{assigns: %{current_user: %AppChat.User{__meta__: #Ecto.Schema.Metadata<:loaded, "user_user">, date_joined: ~N[2018-05-22 02:04:54.000000], email: "testbot1@mail.com", first_name: "", id: 3, is_active: true, is_staff: false, is_superuser: true, last_login: ~N[2018-06-21 13:39:17.111225], last_name: "", password: "pbkdf2_sha256$30000$cisWeRJFh94O$jTspzHNklJr+WKd5q1iPTzLz++eW1plIUoI+3DoZJEI=", user_message: #Ecto.Association.NotLoaded<association :user_message is not loaded>, username: "testbot1@mail.com"}}, channel: AppChat.PrivateChannel, channel_pid: #PID<0.391.0>, endpoint: AppChat.Endpoint, handler: AppChat.UserSocket, id: "user_socket:3", joined: false, pubsub_server: AppChat.PubSub, ref: nil, serializer: Phoenix.Transports.WebSocketSerializer, topic: "private:3:3", transport: Phoenix.Transports.WebSocket, transport_name: :websocket, transport_pid: #PID<0.388.0>})
        (phoenix) lib/phoenix/channel/server.ex:170: Phoenix.Channel.Server.init/1
        (stdlib) gen_server.erl:365: :gen_server.init_it/2
        (stdlib) gen_server.erl:333: :gen_server.init_it/6
        (stdlib) proc_lib.erl:247: :proc_lib.init_p_do_apply/3
[info] Replied private:3:3 :error

Post #2

kokolegorille

Which version of Phoenix?

It looks like Phoenix 1.2 because with newer version, AppChat should be named AppChatWeb.

Post #3

Deathslice246

Yes, I’m using phoenix 1.2. Forgot to mention that sorry.

Post #4

kokolegorille

Phoenix 1.2 is quite back in time… in some of my old channels (Phoenix 1.2.1), I have

defmodule Chatroom.LobbyChannel do
  use Phoenix.Channel

  def join("lobby", _payload, socket) do
    {:ok, socket}
  end
end

You see I use use Phoenix.Channel instead of use AppChat.Web, :channel

I guess You might mix newer syntax with old version.

BTW Your syntax looks good

Post #5

Deathslice246

Ok, but do you have another other insight as to what the problem might be? You said that the phoenix side is fine and that it may be something on client side right?

Post #6

kokolegorille

No, error message is from server side… I was just guessing

Post #7

Deathslice246

Ok then the main question is, why is that I’m able to join the user channel and not the private channel when they are nearly the same code wise? What is getting to me is that it says undefined join/3 function when I have exactly 3 arguments present in the private channel?

Post #8