feat: improve the syntax of ${} in payload templates

apps/emqx_rule_engine/src/emqx_rule_engine.app.src

@@ -1,6 +1,6 @@
 {application, emqx_rule_engine,
  [{description, "EMQX Rule Engine"},
-  {vsn, "4.4.17"}, % strict semver, bump manually!
+  {vsn, "4.4.18"}, % strict semver, bump manually!
   {modules, []},
   {registered, [emqx_rule_engine_sup, emqx_rule_registry, emqx_rule_engine_jwt_sup]},
   {applications, [kernel,stdlib,rulesql,getopt,jose]},

apps/emqx_rule_engine/src/emqx_rule_utils.erl

@@ -71,7 +71,10 @@
           [ float/1
           ]}).
 
--define(EX_PLACE_HOLDER, "(\\$\\{[a-zA-Z0-9\\._]+\\})").
+%% To match any pattern starts with '$' and followed by '{', and closed by a '}' char:
+%% e.g. for string "a${abc}bb", "${abc}" will be matched.
+%% Note that if "${{abc}}" is given, the "${{abc}" should be matched, NOT "${{abc}}".
+-define(EX_PLACE_HOLDER, "(\\$\\{.*?\\})").
 -define(EX_WITHE_CHARS, "\\s"). %% Space and CRLF
 -define(FLOAT_PRECISION, 17).
 

apps/emqx_rule_engine/test/emqx_rule_utils_SUITE.erl

@@ -76,6 +76,25 @@ t_proc_tmpl(_) ->
     Selected = #{a => <<"1">>, b => 1, c => 1.0, d => #{d1 => <<"hi">>}},
     Tks = emqx_rule_utils:preproc_tmpl(<<"a:${a},b:${b},c:${c},d:${d}">>),
     ?assertEqual(<<"a:1,b:1,c:1.0,d:{\"d1\":\"hi\"}">>,
+                 emqx_rule_utils:proc_tmpl(Tks, Selected)),
+    Tks1 = emqx_rule_utils:preproc_tmpl(<<"a:${a},b:${b},c:${c},d:${d.d1}">>),
+    ?assertEqual(<<"a:1,b:1,c:1.0,d:hi">>,
+                 emqx_rule_utils:proc_tmpl(Tks1, Selected)).
+
+t_proc_tmpl_arbitrary_var_name(_) ->
+    Selected = #{<<"中"/utf8>> => <<"1">>,
+                 <<"中-1"/utf8>> => <<"1-1">>,
+                 <<"-_+=<>,/?:;\"'\\[]|">> => 1,
+                 <<"-_+=<>,">> => #{<<"/?:;\"'\\[]|">> => 2},
+                 <<"!@#$%^&*()">> => 1.0,
+                 <<"d">> => #{
+                    <<"$ff">> => <<"oo">>,
+                    <<"${f">> => <<"hi">>,
+                    <<"${f}">> => <<"qq">>
+                }},
+    Tks = emqx_rule_utils:preproc_tmpl(
+        <<"a:${中},a:${中-1},b:${-_+=<>,/?:;\"'\\[]|},b:${-_+=<>,./?:;\"'\\[]|},c:${!@#$%^&*()},d:${d.$ff},d1:${d.${f}}"/utf8>>),
+    ?assertEqual(<<"a:1,a:1-1,b:1,b:2,c:1.0,d:oo,d1:hi}">>,
                  emqx_rule_utils:proc_tmpl(Tks, Selected)).
 
 t_proc_tmpl1(_) ->