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<H1>[99s-extend] REST handler failure</H1>
<B>Daniel Goertzen</B>
<A HREF="mailto:extend%40lists.ninenines.eu?Subject=Re%3A%20%5B99s-extend%5D%20REST%20handler%20failure&In-Reply-To=%3CCAJCf5RzwO4nNcv%3D2Ezf7aMQqFShPhLs4zaYoBBunmzuC7Wp4uQ%40mail.gmail.com%3E"
TITLE="[99s-extend] REST handler failure">daniel.goertzen at gmail.com
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<I>Wed Oct 30 16:46:37 CET 2013</I>
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<PRE>That's what I was looking for, thanks!
Dan.
On Wed, Oct 30, 2013 at 10:25 AM, Tilman Holschuh <<A HREF="https://lists.ninenines.eu/listinfo/extend">tilman.holschuh at gmail.com</A>
><i> wrote:
</I>
><i> Why not let resource_exists/2 return false when your resource does not
</I>><i> exist? You will get 404 on false. This way you separate the implementation
</I>><i> for turning your data to json from checking if the request went to the
</I>><i> correct resource.
</I>><i>
</I>><i> - Tilman
</I>><i>
</I>><i> On 2013-10-30, at 7:58 AM, Daniel Goertzen wrote:
</I>><i>
</I>><i> > Well, this sort of works. I tried this in the response handler:
</I>><i> >
</I>><i> > {ok, Req2} = cowboy_req:reply(404, [] , <<"this is the body
</I>><i> that gets used">>, Req1),
</I>><i> > {<<"this body gets ignored">>, Req2, State};
</I>><i> >
</I>><i> >
</I>><i> >
</I>><i> > The client receives a 404 response, but cowboy crashes:
</I>><i> >
</I>><i> > =ERROR REPORT==== 8-Sep-2013::22:22:03 ===
</I>><i> > Error in process <0.131.0> with exit value:
</I>><i> {function_clause,[{cowboy_req,reply,[200,[],<<31
</I>><i> bytes>>,{http_req,#Port<0.1208>,ranch_tcp,keepalive,<0.131.0>,<<3
</I>><i> bytes>>,'HTTP/1.1',{{192,168,1,187},51017},<<12 bytes>>,undefined,80,<<24
</I>><i> bytes>>,undefined,<<0 bytes>>,undefined,[{channel_num,3}],[{<<10
</I>><i> bytes>>,<<11 bytes>>},{<<4 bytes>>,<<12 bytes>>},{<<6 bytes>>,<<3
</I>><i> bytes>>}],[{<<17 bytes>>,undefined},{<<13 bytes>>,undefined},{<<19
</I>><i> bytes>>,undefined},{<<8 bytes>>,undefined},{<<6 bytes>>,[...
</I>><i> >
</I>><i> >
</I>><i> >
</I>><i> > The issue is that the REST wrapper wants to do the cowboy_req:reply(),
</I>><i> and when we do the call we cause the wrapper's call to fail.
</I>><i> >
</I>><i> > Dan.
</I>><i> >
</I>><i> >
</I>><i> >
</I>><i> > On Tue, Oct 29, 2013 at 4:01 PM, Ivan uemlianin <<A HREF="https://lists.ninenines.eu/listinfo/extend">ivan at llaisdy.com</A>>
</I>><i> wrote:
</I>><i> > Sorry for terse but I only have a phone. Why can't you return a 404
</I>><i> here? Using something like cowboy:reply(404, ...
</I>><i> >
</I>><i> > Ivan
</I>><i> >
</I>><i> > --
</I>><i> > festina lente
</I>><i> >
</I>><i> >
</I>><i> > On 29 Oct 2013, at 21:25, Daniel Goertzen <<A HREF="https://lists.ninenines.eu/listinfo/extend">daniel.goertzen at gmail.com</A>>
</I>><i> wrote:
</I>><i> >
</I>><i> >> My situation is that I have a rest handler that may fail due to invalid
</I>><i> url segments. Example situation:
</I>><i> >>
</I>><i> >>
</I>><i> >> init(_Transport, _Req, _Opts) ->
</I>><i> >> {upgrade, protocol, cowboy_rest}.
</I>><i> >>
</I>><i> >> content_types_provided(Req, State) ->
</I>><i> >> {[{<<"application/json">>, get_json}], Req, State}.
</I>><i> >>
</I>><i> >> get_json(Req0, State) ->
</I>><i> >> {Params, Req1} = lists:mapfoldl(fun cowboy_req:binding/2, Req0,
</I>><i> [param1, param2, param3, ....]),
</I>><i> >>
</I>><i> >> case catch other_module:request(Params) of
</I>><i> >> {'EXIT', {badarg, _}} ->
</I>><i> >> hmmm, Params were bad and I would like to return a 404 code
</I>><i> now.
</I>><i> >> Result ->
</I>><i> >> {jiffy:encode(Result), Req1, State}
</I>><i> >> end.
</I>><i> >>
</I>><i> >>
</I>><i> >>
</I>><i> >> So I would like to return a 404 code when my underlying request
</I>><i> function fails, but it appears my choices are:
</I>><i> >>
</I>><i> >> - return a 200 (ok) response with data.
</I>><i> >> - crash and cause a 500 (Internal Server Error) response to be
</I>><i> returned. Not exactly the sentiment I want.
</I>><i> >>
</I>><i> >>
</I>><i> >> Is there some other way to cause a 404 response?
</I>><i> >>
</I>><i> >> I realize I could add path constraint functions, but I will be
</I>><i> replicating logic from my underlying request function. Furthermore, the
</I>><i> constraint functions consider parameters in isolation, so that won't work
</I>><i> if the validity of parameters is coupled.
</I>><i> >>
</I>><i> >> Thanks,
</I>><i> >> Dan.
</I>><i> >> _______________________________________________
</I>><i> >> Extend mailing list
</I>><i> >> <A HREF="https://lists.ninenines.eu/listinfo/extend">Extend at lists.ninenines.eu</A>
</I>><i> >> <A HREF="http://lists.ninenines.eu:81/listinfo/extend">http://lists.ninenines.eu:81/listinfo/extend</A>
</I>><i> >
</I>><i> > _______________________________________________
</I>><i> > Extend mailing list
</I>><i> > <A HREF="https://lists.ninenines.eu/listinfo/extend">Extend at lists.ninenines.eu</A>
</I>><i> > <A HREF="http://lists.ninenines.eu:81/listinfo/extend">http://lists.ninenines.eu:81/listinfo/extend</A>
</I>><i>
</I>><i>
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