Add cowboy_req:delete_resp_header/2

Both requested and better for making Req opaque.

src/cowboy_req.erl

@@ -71,6 +71,7 @@
 -export([set_resp_body_fun/3]).
 -export([has_resp_header/2]).
 -export([has_resp_body/1]).
+-export([delete_resp_header/2]).
 -export([reply/2]).
 -export([reply/3]).
 -export([reply/4]).
@@ -724,7 +725,6 @@ set_resp_header(Name, Value, Req=#http_req{resp_headers=RespHeaders}) ->
 set_resp_body(Body, Req) ->
 	{ok, Req#http_req{resp_body=Body}}.
 
-
 %% @doc Add a body function to the response.
 %%
 %% The response body may also be set to a content-length - stream-function pair.
@@ -757,6 +757,13 @@ has_resp_body(#http_req{resp_body={Length, _}}) ->
 has_resp_body(#http_req{resp_body=RespBody}) ->
 	iolist_size(RespBody) > 0.
 
+%% Remove a header previously set for the response.
+-spec delete_resp_header(cowboy_http:header(), Req)
+	-> Req when Req::req().
+delete_resp_header(Name, Req=#http_req{resp_headers=RespHeaders}) ->
+	RespHeaders2 = lists:keydelete(Name, 1, RespHeaders),
+	Req#http_req{resp_headers=RespHeaders2}.
+
 %% @equiv reply(Status, [], [], Req)
 -spec reply(cowboy_http:status(), Req) -> {ok, Req} when Req::req().
 reply(Status, Req=#http_req{resp_body=Body}) ->

src/cowboy_rest.erl

@@ -579,9 +579,8 @@ if_modified_since(Req, State, IfModifiedSince) ->
 			end
 	end.
 
-not_modified(Req=#http_req{resp_headers=RespHeaders}, State) ->
-	RespHeaders2 = lists:keydelete(<<"Content-Type">>, 1, RespHeaders),
-	Req2 = Req#http_req{resp_headers=RespHeaders2},
+not_modified(Req, State) ->
+	Req2 = cowboy_req:delete_resp_header(<<"Content-Type">>, Req),
 	{Req3, State2} = set_resp_etag(Req2, State),
 	{Req4, State3} = set_resp_expires(Req3, State2),
 	respond(Req4, State3, 304).