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add support for jexl as additional expression lanaguage
* JEXL (https://github.com/TomFrost/jexl) a library that provides a reich javascript expression language. * update docs * add tests for ngsi & ngsi v2
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‎README.md

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@@ -485,15 +485,19 @@ attributes:
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- **expression**: indicates that the value of the target attribute will not be
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the plain value or the measurement, but an expression based on a combination
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of the reported values. See the
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[Expression Language definition](doc/expressionLanguage.md) for details
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of the reported values. IoT Agent Lib supports two expression languages:
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i) the first one is a native expression language; ii) the second one is
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an wrapper around [JEXL](https://github.com/TomFrost/jexl). For the details
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on the native see: [Expression Language definition](doc/expressionLanguage.md).
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For details on JEXL see: [Javascript Expression Language](https://github.com/TomFrost/jexl#all-the-details).
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- **entity_name**: the presence of this attribute indicates that the value
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will not be stored in the original device entity but in a new entity with an
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ID given by this attribute. The type of this additional entity can be
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configured with the `entity_type` attribute. If no type is configured, the
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device entity type is used instead. Entity names can be defined as
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expressions, using the
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[Expression Language definition](doc/expressionLanguage.md).
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[Expression Language definition](doc/expressionLanguage.md) or
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[Javascript Expression Language](https://github.com/TomFrost/jexl#all-the-details).
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- **entity_type**: configures the type of an alternative entity.
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- **reverse**: add bidirectionality expressions to the attribute. See the
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**bidirectionality** transformation plugin in the

‎doc/expressionLanguage.md

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@@ -17,6 +17,16 @@ The IoTAgent Library provides an expression language for measurement transformat
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information coming from the South Bound APIs to the information reported to the Context Broker. Expressions in this
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language can be configured for provisioned attributes as explained in the Device Provisioning API section in the
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main README.md.
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As an alternative, the IoTAgent Library supports as well [JEXL](https://github.com/TomFrost/jexl).
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In this section we provide only details for the native IoTAgent Library
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expression language. To use JEXL, you will need to replace the native language
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plugin with the JEXL one, e.g.:
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```js
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iotAgentLib.addUpdateMiddleware(iotAgentLib.dataPlugins.mozjexlTransformation.update);
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```
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JEXL language details are discussed [here](https://github.com/TomFrost/jexl#all-the-details).
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## Measurement transformation
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‎lib/fiware-iotagent-lib.js

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@@ -295,6 +295,7 @@ exports.dataPlugins = {
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addEvents: require('./plugins/addEvent'),
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timestampProcess: require('./plugins/timestampProcessPlugin'),
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expressionTransformation: require('./plugins/expressionPlugin'),
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jexlTransformation: require('./plugins/jexlPlugin'),
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multiEntity: require('./plugins/multiEntity'),
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bidirectionalData: require('./plugins/bidirectionalData')
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};

‎lib/plugins/jexlParser.js

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/*
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* Copyright 2016 Telefonica Investigación y Desarrollo, S.A.U
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*
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* This file is part of fiware-iotagent-lib
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*
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* fiware-iotagent-lib is free software: you can redistribute it and/or
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* modify it under the terms of the GNU Affero General Public License as
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* published by the Free Software Foundation, either version 3 of the License,
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* or (at your option) any later version.
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*
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* fiware-iotagent-lib is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public
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* License along with fiware-iotagent-lib.
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* If not, seehttp://www.gnu.org/licenses/.
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*
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* For those usages not covered by the GNU Affero General Public License
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* please contact with::[email protected]
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*
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* Modified by: Daniel Calvo - ATOS Research & Innovation
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*/
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'use strict';
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const jexl = require('jexl');
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var errors = require('../errors'),
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config = require('../commonConfig');
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jexl.addTransform('indexOf', (val, char) => String(val).indexOf(char));
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jexl.addTransform('length', (val) => String(val).length);
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jexl.addTransform('trim', (val) => String(val).trim());
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jexl.addTransform('substr', (val, int1, int2) => String(val).substr(int1, int2));
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function extractContext(attributeList) {
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var context = {};
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var value;
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for (var i = 0; i < attributeList.length; i++) {
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if (Number.parseInt(attributeList[i].value)) {
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value = Number.parseInt(attributeList[i].value);
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} else if (Number.parseFloat(attributeList[i].value)) {
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value = Number.parseFloat(attributeList[i].value);
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} else if (String(attributeList[i].value) === 'true') {
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value = true;
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} else if (String(attributeList[i].value) === 'false') {
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value = false;
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} else {
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value = attributeList[i].value;
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}
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context[attributeList[i].name] = value;
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}
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return context;
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}
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function applyExpression(expression, context, typeInformation) {
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return jexl.evalSync (expression, context);
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}
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function expressionApplier(context, typeInformation) {
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return function(attribute) {
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/**
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* Determines if a value is of type float
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*
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* @param {String} value Value to be analyzed
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* @return {boolean} True if float, False otherwise.
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*/
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function isFloat(value) {
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return !isNaN(value) && value.toString().indexOf('.') !== -1;
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}
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var newAttribute = {
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name: attribute.name,
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type: attribute.type
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};
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/*jshint camelcase: false */
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if (config.checkNgsi2() && attribute.object_id) {
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newAttribute.object_id = attribute.object_id;
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}
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newAttribute.value = applyExpression(attribute.expression, context, typeInformation);
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if (attribute.type === 'Number' && isFloat(newAttribute.value)) {
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newAttribute.value = Number.parseFloat(newAttribute.value);
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}
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else if (attribute.type === 'Number' && Number.parseInt(newAttribute.value)) {
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newAttribute.value = Number.parseInt(newAttribute.value);
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}
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else if (attribute.type === 'Boolean') {
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newAttribute.value = (newAttribute.value === 'true' || newAttribute.value === '1');
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}
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else if (attribute.type === 'None') {
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newAttribute.value = null;
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} else {
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newAttribute.value = String(newAttribute.value);
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}
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return newAttribute;
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};
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}
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function isTransform(identifier) {
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return jexl.getTransform(identifier) === ( null || undefined) ? false : true;
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}
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function contextAvailable(expression, context) {
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var error;
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try{
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var lexer = jexl._getLexer();
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var identifiers = lexer.tokenize(expression).filter(function(token) {
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return token.type === 'identifier';
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});
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var keys = Object.keys(context);
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var validContext = true;
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identifiers.some(function(element) {
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if (!keys.includes(element.value) && !isTransform(element.value)) {
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validContext = false;
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}
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return validContext === false;
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});
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if(validContext) {
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jexl.evalSync (expression, context);
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}
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return validContext;
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} catch (e) {
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error = new errors.InvalidExpression(expression);
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throw error;
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}
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}
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function processExpressionAttributes(typeInformation, list, context) {
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return list
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.filter(function(item) {
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return item.expression && contextAvailable(item.expression, context);
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})
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.map(expressionApplier(context, typeInformation));
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}
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exports.extractContext = extractContext;
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exports.processExpressionAttributes = processExpressionAttributes;
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exports.applyExpression = applyExpression;

‎lib/plugins/jexlPlugin.js

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/*
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* Copyright 2016 Telefonica Investigación y Desarrollo, S.A.U
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*
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* This file is part of fiware-iotagent-lib
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*
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* fiware-iotagent-lib is free software: you can redistribute it and/or
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* modify it under the terms of the GNU Affero General Public License as
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* published by the Free Software Foundation, either version 3 of the License,
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* or (at your option) any later version.
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*
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* fiware-iotagent-lib is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public
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* License along with fiware-iotagent-lib.
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* If not, seehttp://www.gnu.org/licenses/.
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*
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* For those usages not covered by the GNU Affero General Public License
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* please contact with::[email protected]
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*
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* Created by: Federico M. Facca @ Martel Innovate
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*/
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'use strict';
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var _ = require('underscore'),
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parser = require('./jexlParser'),
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config = require('../commonConfig'),
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/*jshint unused:false*/
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logger = require('logops'),
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/*jshint unused:false*/
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context = {
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op: 'IoTAgentNGSI.mozjexPlugin'
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},
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utils = require('./pluginUtils');
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function mergeAttributes(attrList1, attrList2) {
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var finalCollection = _.clone(attrList1),
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additionalItems = [],
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found;
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for (var i = 0; i < attrList2.length; i++) {
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found = false;
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for (var j = 0; j < finalCollection.length; j++) {
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if (finalCollection[j].name === attrList2[i].name) {
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finalCollection[j].value = attrList2[i].value;
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found = true;
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}
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}
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if (!found) {
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additionalItems.push(attrList2[i]);
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}
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}
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return finalCollection.concat(additionalItems);
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}
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function update(entity, typeInformation, callback) {
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function processEntityUpdateNgsi1(entity) {
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var expressionAttributes = [],
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ctx = parser.extractContext(entity.attributes);
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if (typeInformation.active) {
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expressionAttributes = parser.processExpressionAttributes(typeInformation, typeInformation.active, ctx);
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}
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entity.attributes = mergeAttributes(entity.attributes, expressionAttributes);
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return entity;
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}
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function processEntityUpdateNgsi2(attributes) {
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var expressionAttributes = [],
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ctx = parser.extractContext(attributes);
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if (typeInformation.active) {
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expressionAttributes = parser.processExpressionAttributes(typeInformation, typeInformation.active, ctx);
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}
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attributes = mergeAttributes(attributes, expressionAttributes);
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return attributes;
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}
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try {
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if (config.checkNgsi2()) {
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var attsArray = utils.extractAttributesArrayFromNgsi2Entity(entity);
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attsArray = processEntityUpdateNgsi2(attsArray);
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entity = utils.createNgsi2Entity(entity.id, entity.type, attsArray, true);
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} else {
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entity.contextElements = entity.contextElements.map(processEntityUpdateNgsi1);
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}
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callback(null, entity, typeInformation);
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} catch (e) {
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callback(e);
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}
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}
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exports.update = update;

‎package.json

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"body-parser": "~1.19.0",
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"command-shell-lib": "1.0.0",
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"express": "~4.16.4",
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"jexl": "2.1.1",
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"jison": "0.4.18",
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"logops": "2.1.0",
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"moment": "~2.24.0",

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