fix(rules): ensure create_at unchanged after rule is updated

apps/emqx_rule_engine/src/emqx_rule_engine.erl

@@ -124,14 +124,19 @@ load_rules() ->
 -spec create_rule(map()) -> {ok, rule()} | {error, term()}.
 create_rule(Params = #{id := RuleId}) when is_binary(RuleId) ->
     case get_rule(RuleId) of
-        not_found -> do_create_rule(Params);
-        {ok, _} -> {error, {already_exists, RuleId}}
+        not_found -> parse_and_insert(Params, now_ms());
+        {ok, _} -> {error, already_exists}
     end.
 
 -spec update_rule(map()) -> {ok, rule()} | {error, term()}.
 update_rule(Params = #{id := RuleId}) when is_binary(RuleId) ->
-    ok = delete_rule(RuleId),
-    do_create_rule(Params).
+    case get_rule(RuleId) of
+        not_found ->
+            {error, not_found};
+        {ok, #{created_at := CreatedAt}} ->
+            ok = delete_rule(RuleId),
+            parse_and_insert(Params, CreatedAt)
+    end.
 
 -spec(delete_rule(RuleId :: rule_id()) -> ok).
 delete_rule(RuleId) when is_binary(RuleId) ->
@@ -232,13 +237,14 @@ code_change(_OldVsn, State, _Extra) ->
 %% Internal Functions
 %%------------------------------------------------------------------------------
 
-do_create_rule(Params = #{id := RuleId, sql := Sql, outputs := Outputs}) ->
+parse_and_insert(Params = #{id := RuleId, sql := Sql, outputs := Outputs}, CreatedAt) ->
     case emqx_rule_sqlparser:parse(Sql) of
         {ok, Select} ->
             Rule = #{
                 id => RuleId,
                 name => maps:get(name, Params, <<"">>),
-                created_at => erlang:system_time(millisecond),
+                created_at => CreatedAt,
+                updated_at => now_ms(),
                 enable => maps:get(enable, Params, true),
                 sql => Sql,
                 outputs => parse_outputs(Outputs),
@@ -287,5 +293,8 @@ get_all_records(Tab) ->
 maps_foreach(Fun, Map) ->
     lists:foreach(Fun, maps:to_list(Map)).
 
+now_ms() ->
+    erlang:system_time(millisecond).
+
 bin(A) when is_atom(A) -> atom_to_binary(A, utf8);
 bin(B) when is_binary(B) -> B.