Add a POST echo example

examples/echo_post/src/toppage_handler.erl

@@ -0,0 +1,36 @@
+%% Feel free to use, reuse and abuse the code in this file.
+
+%% @doc POST echo handler.
+-module(toppage_handler).
+
+-export([init/3]).
+-export([handle/2]).
+-export([terminate/2]).
+
+init(_Transport, Req, []) ->
+	{ok, Req, undefined}.
+
+handle(Req, State) ->
+	{Method, Req2} = cowboy_http_req:method(Req),
+	{HasBody, Req3} = cowboy_http_req:has_body(Req2),
+	{ok, Req4} = maybe_echo(Method, HasBody, Req3),
+	{ok, Req4, State}.
+
+maybe_echo('POST', true, Req) ->
+	{PostVals, Req2} = cowboy_http_req:body_qs(Req),
+	Echo = proplists:get_value(<<"echo">>, PostVals),
+	echo(Echo, Req2);
+maybe_echo('POST', false, Req) ->
+	cowboy_http_req:reply(400, [], <<"Missing body.">>, Req);
+maybe_echo(_, _, Req) ->
+	%% Method not allowed.
+	cowboy_http_req:reply(405, Req).
+
+echo(undefined, Req) ->
+	cowboy_http_req:reply(400, [], <<"Missing echo parameter.">>, Req);
+echo(Echo, Req) ->
+	cowboy_http_req:reply(200,
+		[{<<"Content-Encoding">>, <<"utf-8">>}], Echo, Req).
+
+terminate(_Req, _State) ->
+	ok.