Stop a websocket connection

Questions / Help
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1

I am implementing a websocket purely using elixir and cowboy. How can i close a websocket connection in the websocket_init/1 function? I want to send a reason to close the connection and then pattern match it in the terminate/3 function, so that i can do some other functions inside it.

def websocket_init(state) do
    info("Initializing connection")
    case Account.get_user(state.id) do
      %User{} ->
        {:ok, state}
      nil ->
        {:error, "No account"}
    end
  end

So that in the terminate/3 function I can do something like this:

def terminate({:error, "No account"}, _req, _state) do
    info("No account")
    :ok
  end

def terminate(_reason, _req, _state) do
   info("Terminating connection")
   :ok
end
2

Try {:stop, "state"} (https://github.com/ninenines/cowboy/blob/db0d6f8d254f2cc01bd458dc41969e0b96991cc3/src/cowboy_websocket.erl#L560) which will invoke the terminate callback (https://github.com/ninenines/cowboy/blob/db0d6f8d254f2cc01bd458dc41969e0b96991cc3/src/cowboy_websocket.erl#L655)

websocket_init must return a CallResult type, defined on https://ninenines.eu/docs/en/cowboy/2.2/manual/cowboy_websocket/

I haven’t tested this myself, but just reading through the source code. This could be incorrect.

3

{:stop, state} works. But the reason in terminate/3 function is same as a normal connection closing. I want it to be different, so that I can pattern match it as shown above

4

Can you include that in the state? It looks like it’s passed through to the terminate call from your stop tuple—if I’m reading this right.

5

Yes. I tried including the reason in the state and now I can pattern match the state and there by do what ever it is that I want.

Thanks man. I was too concentrated on the reason argument of the terminate/3 function that I didn’t look in to other option. Thanks again :slightly_smiling_face: :heart:

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