Merge pull request #1368 from telefonicaid/task/add_hextostring_tranformation_function

add hextostring transformation jexl function

Author: fgalan

CHANGES_NEXT_RELEASE

@@ -1,3 +1,4 @@
+- Add: add hextostring transformation jexl function (#1367)
 - Add: JEXL support to bidirectinal plugin
 - Remove: remove legacy expression support (removing IOTA_DEFAULT_EXPRESSION_LANGUAGE env var and associated defaultExpressionLanguage config.js setting) (#1340)
 - Fix: avoid usage of newlines in logs (#1342)
@@ -6,4 +7,4 @@
 - Fix: allow use static attributes from group in entityNameExp of group
 - Fix: disable device attribute entity_name validation using pattern
 - Fix: reenable invocation of custom plugins on update (#1348)
-- Fix: change level of log about not context available for apply expression from warn to info
+- Fix: change level of log about not context available for apply expression from warn to info

doc/api.md

@@ -578,6 +578,7 @@ Current common transformation set:
 | toisostring: (d)                     | `new Date(d).toISOString()`                                                                                             |
 | localestring: (d, timezone, options) | `new Date(d).toLocaleString(timezone, options)`                                                                         |
 | now: ()                              | `Date.now()`                                                                                                            |
+| hextostring: (val)                   | `new TextDecoder().decode(new Uint8Array(val.match(/.{1,2}/g).map(byte => parseInt(byte, 16))))`                       |
 
 You have available this [JEXL interactive playground][99] with all the transformations already loaded, in which you can
 test all the functions described above.

lib/jexlTranformsMap.js

@@ -78,7 +78,8 @@ const map = {
     toisostring: (d) => new Date(d).toISOString(),
     // https://developer.mozilla.org/es/docs/Web/JavaScript/Reference/Global_Objects/Date/toLocaleString
     localestring: (d, timezone, options) => new Date(d).toLocaleString(timezone, options),
-    now: () => Date.now()
+    now: () => Date.now(),
+    hextostring: (val) => new TextDecoder().decode(new Uint8Array(val.match(/.{1,2}/g).map(byte => parseInt(byte, 16))))
 };
 
 exports.map = map;