handle empty array

README.md

@@ -104,7 +104,7 @@ To subscribe to one or more users, make use of the `subscribe` event:
 }
 ```
 
-By doing so, you will receive real-time updates for the specified users within the `ids` array.
+By doing so, you will receive real-time updates for the specified users within the `ids` array. If the `ids` is an empty list (`[]`) or `null`, it will unsubscribe from all the subscriptions without returning anything.
 
 To update subscribers, resend the same data with the updated `ids` value.
 

lib/revard/gateway/listener.ex

@@ -48,20 +48,33 @@ defmodule Revard.Gateway.Listener do
     {:ok, state}
   end
 
+  defp match_message(%{"event" => "subscribe", "ids" => nil}, state) do
+    # Unsubscribe all
+    Enum.each(state, &Phoenix.PubSub.unsubscribe(@pubsub, &1))
+
+    {:ok, []}
+  end
+
+  defp match_message(%{"event" => "subscribe", "ids" => []} = message, state) do
+    message
+    |> Map.put("ids", nil)
+    |> match_message(state)
+  end
+
   defp match_message(%{"event" => "subscribe", "ids" => ids}, state) when is_list(ids) do
     # Check format
     if Enum.all?(ids, &check_id/1) do
       # Unsubscribe all
       Enum.each(state, &Phoenix.PubSub.unsubscribe(@pubsub, &1))
 
-      # Subscribe given ones
-      Enum.each(ids, &Phoenix.PubSub.subscribe(@pubsub, &1))
-
       # Debug message
       Logger.debug(
-        "Connection #{inspect(self())} subscribed to following id(s): #{inspect(ids)} (socket)"
+        "Connection #{inspect(self())} subscribing to following id(s): #{inspect(ids)} (socket)"
       )
 
+      # Subscribe given ones
+      Enum.each(ids, &Phoenix.PubSub.subscribe(@pubsub, &1))
+
       # Reply with initial message
       initial_message =
         %{type: "init", data: Revard.Storage.Users.get(ids)}
@@ -73,13 +86,6 @@ defmodule Revard.Gateway.Listener do
     end
   end
 
-  defp match_message(%{"event" => "subscribe", "ids" => nil}, state) do
-    # Unsubscribe all
-    Enum.each(state, &Phoenix.PubSub.unsubscribe(@pubsub, &1))
-
-    {:ok, []}
-  end
-
   defp match_message(_message, state) do
     invalid_payload_error(state)
   end