archives/extend/2013-October/000292.html


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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=%3CCAJCf5Rx_o66FDE-91kX_%3DKBQou9wcx%2BUEenGPFYLE2nR_PRh8g%40mail.gmail.com%3E"
       TITLE="[99s-extend] REST handler failure">daniel.goertzen at gmail.com
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    <I>Wed Oct 30 16:32:47 CET 2013</I>
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<PRE>Returning 'halt' caused a status code of 204.

Dan.


On Wed, Oct 30, 2013 at 10:27 AM, Ivan uemlianin &lt;<A HREF="https://lists.ninenines.eu/listinfo/extend">ivan at llaisdy.com</A>&gt; wrote:

&gt;<i> Instead of &lt;&lt;&quot;this body ignored&quot;&gt;&gt; can you return the atom halt?
</I>&gt;<i>
</I>&gt;<i> #dontevenhaveanyofmycodewithme:(
</I>&gt;<i>
</I>&gt;<i> Ivan
</I>&gt;<i>
</I>&gt;<i> --
</I>&gt;<i> festina lente
</I>&gt;<i>
</I>&gt;<i>
</I>&gt;<i> On 30 Oct 2013, at 15:58, Daniel Goertzen &lt;<A HREF="https://lists.ninenines.eu/listinfo/extend">daniel.goertzen at gmail.com</A>&gt;
</I>&gt;<i> wrote:
</I>&gt;<i>
</I>&gt;<i> Well, this sort of works.  I tried this in the response handler:
</I>&gt;<i>
</I>&gt;<i>             {ok, Req2} = cowboy_req:reply(404, [] , &lt;&lt;&quot;this is the body
</I>&gt;<i> that gets used&quot;&gt;&gt;, Req1),
</I>&gt;<i>             {&lt;&lt;&quot;this body gets ignored&quot;&gt;&gt;, Req2, State};
</I>&gt;<i>
</I>&gt;<i>
</I>&gt;<i>
</I>&gt;<i> The client receives a 404 response, but cowboy crashes:
</I>&gt;<i>
</I>&gt;<i> =ERROR REPORT==== 8-Sep-2013::22:22:03 ===
</I>&gt;<i> Error in process &lt;0.131.0&gt; with exit value:
</I>&gt;<i> {function_clause,[{cowboy_req,reply,[200,[],&lt;&lt;31
</I>&gt;<i> bytes&gt;&gt;,{http_req,#Port&lt;0.1208&gt;,ranch_tcp,keepalive,&lt;0.131.0&gt;,&lt;&lt;3
</I>&gt;<i> bytes&gt;&gt;,'HTTP/1.1',{{192,168,1,187},51017},&lt;&lt;12 bytes&gt;&gt;,undefined,80,&lt;&lt;24
</I>&gt;<i> bytes&gt;&gt;,undefined,&lt;&lt;0 bytes&gt;&gt;,undefined,[{channel_num,3}],[{&lt;&lt;10
</I>&gt;<i> bytes&gt;&gt;,&lt;&lt;11 bytes&gt;&gt;},{&lt;&lt;4 bytes&gt;&gt;,&lt;&lt;12 bytes&gt;&gt;},{&lt;&lt;6 bytes&gt;&gt;,&lt;&lt;3
</I>&gt;<i> bytes&gt;&gt;}],[{&lt;&lt;17 bytes&gt;&gt;,undefined},{&lt;&lt;13 bytes&gt;&gt;,undefined},{&lt;&lt;19
</I>&gt;<i> bytes&gt;&gt;,undefined},{&lt;&lt;8 bytes&gt;&gt;,undefined},{&lt;&lt;6 bytes&gt;&gt;,[...
</I>&gt;<i>
</I>&gt;<i>
</I>&gt;<i>
</I>&gt;<i> The issue is that the REST wrapper wants to do the cowboy_req:reply(), and
</I>&gt;<i> when we do the call we cause the wrapper's call to fail.
</I>&gt;<i>
</I>&gt;<i> Dan.
</I>&gt;<i>
</I>&gt;<i>
</I>&gt;<i>
</I>&gt;<i> On Tue, Oct 29, 2013 at 4:01 PM, Ivan uemlianin &lt;<A HREF="https://lists.ninenines.eu/listinfo/extend">ivan at llaisdy.com</A>&gt; wrote:
</I>&gt;<i>
</I>&gt;&gt;<i> Sorry for terse but I only have a phone. Why can't you return a 404 here?
</I>&gt;&gt;<i>  Using something like cowboy:reply(404, ...
</I>&gt;&gt;<i>
</I>&gt;&gt;<i> Ivan
</I>&gt;&gt;<i>
</I>&gt;&gt;<i> --
</I>&gt;&gt;<i> festina lente
</I>&gt;&gt;<i>
</I>&gt;&gt;<i>
</I>&gt;&gt;<i> On 29 Oct 2013, at 21:25, Daniel Goertzen &lt;<A HREF="https://lists.ninenines.eu/listinfo/extend">daniel.goertzen at gmail.com</A>&gt;
</I>&gt;&gt;<i> wrote:
</I>&gt;&gt;<i>
</I>&gt;&gt;<i> My situation is that I have a rest handler that may fail due to invalid
</I>&gt;&gt;<i> url segments.  Example situation:
</I>&gt;&gt;<i>
</I>&gt;&gt;<i>
</I>&gt;&gt;<i> init(_Transport, _Req, _Opts) -&gt;
</I>&gt;&gt;<i>         {upgrade, protocol, cowboy_rest}.
</I>&gt;&gt;<i>
</I>&gt;&gt;<i> content_types_provided(Req, State) -&gt;
</I>&gt;&gt;<i>     {[{&lt;&lt;&quot;application/json&quot;&gt;&gt;, get_json}], Req, State}.
</I>&gt;&gt;<i>
</I>&gt;&gt;<i> get_json(Req0, State) -&gt;
</I>&gt;&gt;<i>     {Params, Req1} = lists:mapfoldl(fun cowboy_req:binding/2, Req0,
</I>&gt;&gt;<i> [param1, param2, param3, ....]),
</I>&gt;&gt;<i>
</I>&gt;&gt;<i>     case catch other_module:request(Params) of
</I>&gt;&gt;<i>         {'EXIT', {badarg, _}} -&gt;
</I>&gt;&gt;<i>             hmmm, Params were bad and I would like to return a 404 code
</I>&gt;&gt;<i> now.
</I>&gt;&gt;<i>         Result -&gt;
</I>&gt;&gt;<i>             {jiffy:encode(Result), Req1, State}
</I>&gt;&gt;<i>     end.
</I>&gt;&gt;<i>
</I>&gt;&gt;<i>
</I>&gt;&gt;<i>
</I>&gt;&gt;<i> So I would like to return a 404 code when my underlying request function
</I>&gt;&gt;<i> fails, but it appears my choices are:
</I>&gt;&gt;<i>
</I>&gt;&gt;<i> - return a 200 (ok) response with data.
</I>&gt;&gt;<i> - crash and cause a 500 (Internal Server Error) response to be returned.
</I>&gt;&gt;<i> Not exactly the sentiment I want.
</I>&gt;&gt;<i>
</I>&gt;&gt;<i>
</I>&gt;&gt;<i> Is there some other way to cause a 404 response?
</I>&gt;&gt;<i>
</I>&gt;&gt;<i> I realize I could add path constraint functions, but I will be
</I>&gt;&gt;<i> replicating logic from my underlying request function.  Furthermore, the
</I>&gt;&gt;<i> constraint functions consider parameters in isolation, so that won't work
</I>&gt;&gt;<i> if the validity of parameters is coupled.
</I>&gt;&gt;<i>
</I>&gt;&gt;<i> Thanks,
</I>&gt;&gt;<i> Dan.
</I>&gt;&gt;<i>
</I>&gt;&gt;<i> _______________________________________________
</I>&gt;&gt;<i> Extend mailing list
</I>&gt;&gt;<i> <A HREF="https://lists.ninenines.eu/listinfo/extend">Extend at lists.ninenines.eu</A>
</I>&gt;&gt;<i> <A HREF="http://lists.ninenines.eu:81/listinfo/extend">http://lists.ninenines.eu:81/listinfo/extend</A>
</I>&gt;&gt;<i>
</I>&gt;&gt;<i>
</I>&gt;<i>
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