Task/reuse apply expression current context

CHANGES_NEXT_RELEASE

@@ -1,3 +1,4 @@
+- Add: save result of apply expression attribute into current context for futher usages (#1305)
 - Add: skipValue for expression to allow skip attribute when match with result of apply expression (#1353)
 - Add: add hextostring transformation jexl function (#1367)
 - Add: JEXL support to bidirectinal plugin

lib/services/ngsi/entities-NGSI-v2.js

@@ -769,12 +769,18 @@ function sendUpdateValueNgsi2(entityName, attributes, typeInformation, token, ca
                     }
                 } catch (e) {
                     logger.error(context, 'sendUpdateValueNgsi2 apply expression exception=%j', e);
-                    res = ctxt[attr.name]; // TBD: add reference to test
+                    if (attr && attr.name) {
+                        res = ctxt[attr.name];
+                    }
                 }
                 // jexl expression plugin
                 newAttr.value = res;
 
                 logger.debug(context, 'sendUpdateValueNgsi2 apply expression result=%j newAttr=%j', res, newAttr);
+                // update current context with value
+                if (attr && attr.name && ctxt[attr.name] !== undefined) {
+                    ctxt[attr.name] = newAttr.value;
+                }
             }
 
             // Apply Multientity: entity_type and entity_name in attributes are in typeInformation.active

test/unit/ngsiv2/expressions/jexlBasedTransformations-test.js

@@ -125,7 +125,7 @@ const iotAgentConfig = {
                 {
                     name: 'weather',
                     type: 'Summary',
-                    expression: '"Humidity " + (humidity / 2) + " and pressure " + (pressure * 20)'
+                    expression: '"Humidity " + (humidity / 2) + " and pressure " + (p * 20)'
                 },
                 {
                     object_id: 'a',