如何在cowboy websocket处理程序中处理异常？

Question

我试图抓住无效的json，而解析它与jiffy在牛仔web套接字处理程序。如果json是有效的/无效的，我想转发一个适当的消息到websocket_info，它将回复客户端。这是我的代码。

websocket_handle({text, Msg}, Req, State) ->

lager:info("Got message ~p",[Msg]),

try  jiffy:decode(Msg) of 

    {[{A,B}]}->{{[{A,B}]},Req,State};

    _->{{invalid,Msg},Req,State}

catch
    _:_->
        {{invalid,Msg},Req,State}
end;

websocket_handle(_Data, Req, State) ->

                 {ok, Req, State}.

websocket_info({[{A,B}]},Req,State) ->

               {reply,{text,jiffy:encode({registered,B})},Req,State};

websocket_info({invalid,Msg},Req,State)->

              {reply,{text,jiffy:encode({error,<<"invalid json">>})},Req,State};

这会导致运行时异常。

12:07:48.406[错误]牧场侦听器http已连接到进程

那我该怎么做呢？

Answer 1

回复应该从websocket_handle返回：

websocket_handle({text, Msg}, Req, State) ->
    lager:info("Got message ~p", [Msg]),
    try jiffy:decode(Msg) of 
        {[{A, B}]}->
            {reply, {text, jiffy:encode({[{registered,B}]})}, Req, State};
        _ -> 
            {reply, {text, jiffy:encode({[{error,<<"invalid json">>}]})}, Req, State} 
    catch
        _:_ ->
            {reply, {text, jiffy:encode({[{error,<<"invalid json">>}]})}, Req, State};
    end;

websocket_handle(_Data, Req, State) ->
    {ok, Req, State}.

websocket_info(_Info, Req, State) ->
    {ok, Req, State}.