Add set_resp_headers_list

src/cowboy_req.erl

@@ -68,6 +68,7 @@
 -export([resp_headers/1]).
 -export([set_resp_header/3]).
 -export([set_resp_headers/2]).
+-export([set_resp_headers_list/2]).
 -export([has_resp_header/2]).
 -export([delete_resp_header/2]).
 -export([set_resp_body/2]).
@@ -366,6 +367,30 @@ uri2_test() ->
 	<<"http://localhost/path?dummy=2785">> = iolist_to_binary(uri(Req, #{port => 80})),
 	<<"https://localhost/path?dummy=2785">> = iolist_to_binary(uri(Req, #{scheme => "https", port => 443})),
 	ok.
+
+resp_headers_test() ->
+	Req = #{
+		scheme => <<"http">>, host => <<"localhost">>, port => 8080,
+		path => <<"/path">>, qs => <<"dummy=2785">>
+	},
+	#{resp_headers := RespHeaders} = set_resp_headers_list([
+		{<<"Name">>, <<"Cormano">>},
+		{<<"Name">>, <<"Paco">>},
+		{<<"X-MyHeader">>, <<"custom-header">>},
+		{<<"game-name">>, "Sunset"},
+		{<<"game-name">>, "Riders"},
+		{<<"header">>, ["io", "data"]},
+		{<<"header">>, ["header"]}
+	], #{}, Req),
+
+	#{
+		<<"Name">> := <<"Cormano, Paco">>,
+		<<"X-MyHeader">> := <<"custom-header">>,
+		<<"game-name">> := <<"Sunset, Riders">>,
+		<<"header">> := <<"iodata, header">>
+	 } = RespHeaders,
+
+	ok.
 -endif.
 
 -spec binding(atom(), req()) -> any() | undefined.
@@ -726,6 +751,30 @@ set_resp_header(Name, Value, Req=#{resp_headers := RespHeaders}) ->
 set_resp_header(Name,Value, Req) ->
 	Req#{resp_headers => #{Name => Value}}.
 
+% @todo make it work with iodata(), for now only bitstrings are accepted
+
+-spec set_resp_headers_list(list({ binary(), iodata() }), Req)
+	-> Req when Req::req().
+set_resp_headers_list(HeaderTupleList, Req) ->
+	set_resp_headers_list(HeaderTupleList, #{}, Req).
+
+set_resp_headers_list([], Map, Req) ->
+	set_resp_headers(Map, Req);
+
+set_resp_headers_list([{<<"set-cookie">>, _} | Headers], Map, Req) ->
+	set_resp_headers_list(Headers, Map, Req);
+set_resp_headers_list([{Name, Value} | Headers], Map, Req) ->
+	BinaryValue = iolist_to_binary(Value),
+	NewHeaderValue = case maps:get(Name, Map, undefined) of
+		undefined -> BinaryValue;
+		ExistingValue ->
+			<<ExistingValue/binary, ", ", BinaryValue/binary>>
+	end,
+
+	Map1 = maps:put(Name, NewHeaderValue, Map),
+
+	set_resp_headers_list(Headers, Map1, Req).
+
 -spec set_resp_headers(cowboy:http_headers(), Req)
 	-> Req when Req::req().
 set_resp_headers(#{<<"set-cookie">> := _}, _) ->