[99s-extend] REST handler failure

[Daniel Goertzen]

Well, this sort of works.  I tried this in the response handler:

            {ok, Req2} = cowboy_req:reply(404, [] , <<"this is the body
that gets used">>, Req1),
            {<<"this body gets ignored">>, Req2, State};



The client receives a 404 response, but cowboy crashes:

=ERROR REPORT==== 8-Sep-2013::22:22:03 ===
Error in process <0.131.0> with exit value:
{function_clause,[{cowboy_req,reply,[200,[],<<31
bytes>>,{http_req,#Port<0.1208>,ranch_tcp,keepalive,<0.131.0>,<<3
bytes>>,'HTTP/1.1',{{192,168,1,187},51017},<<12 bytes>>,undefined,80,<<24
bytes>>,undefined,<<0 bytes>>,undefined,[{channel_num,3}],[{<<10
bytes>>,<<11 bytes>>},{<<4 bytes>>,<<12 bytes>>},{<<6 bytes>>,<<3
bytes>>}],[{<<17 bytes>>,undefined},{<<13 bytes>>,undefined},{<<19
bytes>>,undefined},{<<8 bytes>>,undefined},{<<6 bytes>>,[...



The issue is that the REST wrapper wants to do the cowboy_req:reply(), and
when we do the call we cause the wrapper's call to fail.

Dan.



On Tue, Oct 29, 2013 at 4:01 PM, Ivan uemlianin <ivan at llaisdy.com> wrote:

> Sorry for terse but I only have a phone. Why can't you return a 404 here?
>  Using something like cowboy:reply(404, ...
>
> Ivan
>
> --
> festina lente
>
>
> On 29 Oct 2013, at 21:25, Daniel Goertzen <daniel.goertzen at gmail.com>
> wrote:
>
> My situation is that I have a rest handler that may fail due to invalid
> url segments.  Example situation:
>
>
> init(_Transport, _Req, _Opts) ->
>         {upgrade, protocol, cowboy_rest}.
>
> content_types_provided(Req, State) ->
>     {[{<<"application/json">>, get_json}], Req, State}.
>
> get_json(Req0, State) ->
>     {Params, Req1} = lists:mapfoldl(fun cowboy_req:binding/2, Req0,
> [param1, param2, param3, ....]),
>
>     case catch other_module:request(Params) of
>         {'EXIT', {badarg, _}} ->
>             hmmm, Params were bad and I would like to return a 404 code
> now.
>         Result ->
>             {jiffy:encode(Result), Req1, State}
>     end.
>
>
>
> So I would like to return a 404 code when my underlying request function
> fails, but it appears my choices are:
>
> - return a 200 (ok) response with data.
> - crash and cause a 500 (Internal Server Error) response to be returned.
> Not exactly the sentiment I want.
>
>
> Is there some other way to cause a 404 response?
>
> I realize I could add path constraint functions, but I will be replicating
> logic from my underlying request function.  Furthermore, the constraint
> functions consider parameters in isolation, so that won't work if the
> validity of parameters is coupled.
>
> Thanks,
> Dan.
>
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