From 1110b5d8f5768e314ffcb1570b7d8beb48028f60 Mon Sep 17 00:00:00 2001
From: Stefan Strigler <stefan.strigler@emqx.io>
Date: Fri, 7 Jul 2023 13:31:57 +0200
Subject: [PATCH] fix(emqx_retainer): return 404 in delete if topic not found

---
 apps/emqx_retainer/src/emqx_retainer.app.src        |  2 +-
 apps/emqx_retainer/src/emqx_retainer_api.erl        | 13 +++++++++++--
 apps/emqx_retainer/test/emqx_retainer_api_SUITE.erl |  1 +
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/apps/emqx_retainer/src/emqx_retainer.app.src b/apps/emqx_retainer/src/emqx_retainer.app.src
index d13359509..f117fda05 100644
--- a/apps/emqx_retainer/src/emqx_retainer.app.src
+++ b/apps/emqx_retainer/src/emqx_retainer.app.src
@@ -2,7 +2,7 @@
 {application, emqx_retainer, [
     {description, "EMQX Retainer"},
     % strict semver, bump manually!
-    {vsn, "5.0.14"},
+    {vsn, "5.0.15"},
     {modules, []},
     {registered, [emqx_retainer_sup]},
     {applications, [kernel, stdlib, emqx, emqx_ctl]},
diff --git a/apps/emqx_retainer/src/emqx_retainer_api.erl b/apps/emqx_retainer/src/emqx_retainer_api.erl
index 7b1337140..3274f0e4c 100644
--- a/apps/emqx_retainer/src/emqx_retainer_api.erl
+++ b/apps/emqx_retainer/src/emqx_retainer_api.erl
@@ -102,6 +102,7 @@ schema(?PREFIX ++ "/message/:topic") ->
             parameters => parameters(),
             responses => #{
                 204 => <<>>,
+                404 => error_codes(['NOT_FOUND'], ?DESC(message_not_exist)),
                 400 => error_codes(
                     ['BAD_REQUEST'],
                     ?DESC(unsupported_backend)
@@ -187,8 +188,16 @@ with_topic(get, #{bindings := Bindings}) ->
     end;
 with_topic(delete, #{bindings := Bindings}) ->
     Topic = maps:get(topic, Bindings),
-    emqx_retainer_mnesia:delete_message(undefined, Topic),
-    {204}.
+    case emqx_retainer_mnesia:page_read(undefined, Topic, 1, 1) of
+        {ok, []} ->
+            {404, #{
+                code => <<"NOT_FOUND">>,
+                message => <<"Viewed message doesn't exist">>
+            }};
+        {ok, _} ->
+            emqx_retainer_mnesia:delete_message(undefined, Topic),
+            {204}
+    end.
 
 format_message(#message{
     id = ID,
diff --git a/apps/emqx_retainer/test/emqx_retainer_api_SUITE.erl b/apps/emqx_retainer/test/emqx_retainer_api_SUITE.erl
index 61eee0510..d00ade556 100644
--- a/apps/emqx_retainer/test/emqx_retainer_api_SUITE.erl
+++ b/apps/emqx_retainer/test/emqx_retainer_api_SUITE.erl
@@ -218,6 +218,7 @@ t_lookup_and_delete(_) ->
     {ok, []} = request_api(delete, API),
 
     {error, {"HTTP/1.1", 404, "Not Found"}} = request_api(get, API),
+    {error, {"HTTP/1.1", 404, "Not Found"}} = request_api(delete, API),
 
     ok = emqtt:disconnect(C1).