$match - raise an explicit error if no return value is available, i.e., raise and undefined result that is propagated to the caller

Author: gorenje

src/erlang_red_jsonata.erl

@@ -49,6 +49,14 @@ execute(JSONata, Msg) ->
                         "jsonata unsupported function: ~p", element(3, H)
                     )
                 )};
+        error:undefined:Stacktrace ->
+            [H | _] = Stacktrace,
+            {undefined,
+                list_to_binary(
+                    io_lib:format(
+                        "jsonata undefined result: ~p", element(3, H)
+                    )
+                )};
         E:M:S ->
             {exception, {E, M, S}}
     end.
@@ -285,7 +293,7 @@ handle_local_function(
     Args = [global],
     case re:run(any_to_list(Str), R, [{capture, all, binary} | Args]) of
         nomatch ->
-            undefined;
+            erlang:error(undefined, [{"$match", Args}]);
         {match, CaptureBinary} ->
             {match, CaptureIdx} =
                 re:run(any_to_list(Str), R, [{capture, all, index} | Args]),
@@ -313,9 +321,9 @@ handle_local_function(
     );
 handle_local_function(
     jsonata_match,
-    [_Str, _RegExp, MatchLimit]
+    [_Str, _RegExp, MatchLimit] = Args
 ) when is_integer(MatchLimit), MatchLimit =:= 0 ->
-    undefined;
+    erlang:error(undefined, [{"$match", Args}]);
 handle_local_function(
     jsonata_match,
     [Str, RegExp, MatchLimit]
@@ -421,8 +429,6 @@ match_capture_objects(
     match_capture_objects(RestBinary, RestIndicies, [CapHsh | Acc]).
 %%
 %%
-match_capture_limit(undefined, _, _) ->
-    undefined;
 match_capture_limit(_Result, 0, [Hd | []] = _Acc) ->
     Hd;
 match_capture_limit(_Result, 0, Acc) ->

test/erlang_red_jsonata_test.erl

@@ -119,15 +119,17 @@ match_operator_multiple_matches_with_limit_test() ->
         )
     ),
 
+    %% undefined return value is generated when there is no match or no
+    %% no result. The corresponding attribute on the msg object isn't defined.
     ?assertEqual(
-        {ok, undefined},
-        erlang_red_jsonata:execute(
+        undefined,
+        element(1, erlang_red_jsonata:execute(
             "$match($$.payload, /([0-9]+)([a-z]+)([0-9]+)([a-z]+)/, 0)",
             #{
                 <<"payload">> =>
                     <<"123abc456def|||789ghi012jkl|||345mno678pqr||">>
             }
-        )
+        ))
     ),
 
     {exception,
@@ -190,15 +192,17 @@ match_operator_multiple_matches_with_limit_test() ->
             }
         )
     ),
+    %% undefined because no match is found, this will result in the msg variable
+    %% that should be assigned this result not to be defined.
     ?assertEqual(
-        {ok, undefined},
-        erlang_red_jsonata:execute(
+        undefined,
+        element(1, erlang_red_jsonata:execute(
             "$match($$.payload, /([0-9]+)([a-z]+)([0-9]+)([a-z]+)/, $$.limit)",
             #{
                 <<"payload">> => <<"3">>,
                 <<"limit">> => <<"2">>
             }
-        )
+        ))
     ).
 
 flatten_test() ->