From 6b020b4a019ed630d7b126c9d2712b2dbf7bb949 Mon Sep 17 00:00:00 2001
From: DDDHuang <44492639+DDDHuang@users.noreply.github.com>
Date: Tue, 25 Jan 2022 10:53:21 +0800
Subject: [PATCH 1/2] fix(api): query client subscriptions from cluster empty
 check

---
 apps/emqx_management/src/emqx_mgmt.erl | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/apps/emqx_management/src/emqx_mgmt.erl b/apps/emqx_management/src/emqx_mgmt.erl
index 8148e4487..5909c9dc2 100644
--- a/apps/emqx_management/src/emqx_mgmt.erl
+++ b/apps/emqx_management/src/emqx_mgmt.erl
@@ -269,10 +269,14 @@ list_authz_cache(ClientId) ->
 
 list_client_subscriptions(ClientId) ->
     Results = [client_subscriptions(Node, ClientId) || Node <- mria_mnesia:running_nodes()],
-    Expected = lists:filter(fun({error, _}) -> false;
-                               ([]) -> false;
-                               (_) -> true
-                            end, Results),
+    Filter =
+        fun
+            ({error, _}) ->
+                false;
+            ({_Node, List}) ->
+                erlang:is_list(List) andalso 0 < erlang:length(List)
+        end,
+    Expected = lists:filter(Filter, Results),
     case Expected of
         [] -> [];
         [Result | _] -> Result

From e07ecd52111323d679da0fbb5cabc1d124d01ef1 Mon Sep 17 00:00:00 2001
From: DDDHuang <44492639+DDDHuang@users.noreply.github.com>
Date: Tue, 25 Jan 2022 11:10:32 +0800
Subject: [PATCH 2/2] fix(api): client subscriptions formatter fun bad match

---
 apps/emqx_management/src/emqx_mgmt.erl        |  3 +--
 .../src/emqx_mgmt_api_clients.erl             | 20 ++++++++++++++-----
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/apps/emqx_management/src/emqx_mgmt.erl b/apps/emqx_management/src/emqx_mgmt.erl
index 5909c9dc2..20701b937 100644
--- a/apps/emqx_management/src/emqx_mgmt.erl
+++ b/apps/emqx_management/src/emqx_mgmt.erl
@@ -276,8 +276,7 @@ list_client_subscriptions(ClientId) ->
             ({_Node, List}) ->
                 erlang:is_list(List) andalso 0 < erlang:length(List)
         end,
-    Expected = lists:filter(Filter, Results),
-    case Expected of
+    case lists:filter(Filter, Results) of
         [] -> [];
         [Result | _] -> Result
     end.
diff --git a/apps/emqx_management/src/emqx_mgmt_api_clients.erl b/apps/emqx_management/src/emqx_mgmt_api_clients.erl
index 9cc5d3016..5cb40d519 100644
--- a/apps/emqx_management/src/emqx_mgmt_api_clients.erl
+++ b/apps/emqx_management/src/emqx_mgmt_api_clients.erl
@@ -513,11 +513,21 @@ subscribe_batch(post, #{bindings := #{clientid := ClientID}, body := TopicInfos}
     subscribe_batch(#{clientid => ClientID, topics => Topics}).
 
 subscriptions(get, #{bindings := #{clientid := ClientID}}) ->
-    {Node, Subs0} = emqx_mgmt:list_client_subscriptions(ClientID),
-    Subs = lists:map(fun({Topic, SubOpts}) ->
-        #{node => Node, clientid => ClientID, topic => Topic, qos => maps:get(qos, SubOpts)}
-    end, Subs0),
-    {200, Subs}.
+    case emqx_mgmt:list_client_subscriptions(ClientID) of
+        [] ->
+            {200, []};
+        {Node, Subs} ->
+            Formatter =
+                fun({Topic, SubOpts}) ->
+                    #{
+                        node => Node,
+                        clientid => ClientID,
+                        topic => Topic,
+                        qos => maps:get(qos, SubOpts)
+                    }
+                end,
+        {200, lists:map(Formatter, Subs)}
+    end.
 
 set_keepalive(put, #{bindings := #{clientid := ClientID}, query_string := Query}) ->
     case maps:find(<<"interval">>, Query) of