13-using-operator-decorators.js

'use strict'
/*
 * This example demonstrates using operator decorators.
 *
 * In this example, a fact contains a list of strings and we want to check if any of these are valid.
 *
 * Usage:
 *   node ./examples/12-using-operator-decorators.js
 *
 * For detailed output:
 *   DEBUG=json-rules-engine node ./examples/12-using-operator-decorators.js
 */

require('colors')
const { Engine } = require('json-rules-engine')

async function start () {
  /**
   * Setup a new engine
   */
  const engine = new Engine()

  /**
   * Add a rule for validating a tag (fact)
   * against a set of tags that are valid (also a fact)
   */
  const validTags = {
    conditions: {
      all: [{
        fact: 'tags',
        operator: 'everyFact:in',
        value: { fact: 'validTags' }
      }]
    },
    event: {
      type: 'valid tags'
    }
  }

  engine.addRule(validTags)

  engine.addFact('validTags', ['dev', 'staging', 'load', 'prod'])

  let facts

  engine
    .on('success', event => {
      console.log(facts.tags.join(', ') + ' WERE'.green + ' all ' + event.type)
    })
    .on('failure', event => {
      console.log(facts.tags.join(', ') + ' WERE NOT'.red + ' all ' + event.type)
    })

  // first run with valid tags
  facts = { tags: ['dev', 'prod'] }
  await engine.run(facts)

  // second run with an invalid tag
  facts = { tags: ['dev', 'deleted'] }
  await engine.run(facts)

  // add a new decorator to allow for a case-insensitive match
  engine.addOperatorDecorator('caseInsensitive', (factValue, jsonValue, next) => {
    return next(factValue.toLowerCase(), jsonValue.toLowerCase())
  })

  // new rule for case-insensitive validation
  const caseInsensitiveValidTags = {
    conditions: {
      all: [{
        fact: 'tags',
        // everyFact has someValue that caseInsensitive is equal
        operator: 'everyFact:someValue:caseInsensitive:equal',
        value: { fact: 'validTags' }
      }]
    },
    event: {
      type: 'valid tags (case insensitive)'
    }
  }

  engine.addRule(caseInsensitiveValidTags)

  // third run with a tag that is valid if case insensitive
  facts = { tags: ['dev', 'PROD'] }
  await engine.run(facts)
}
start()

/*
 * OUTPUT:
 *
 * dev, prod WERE all valid tags
 * dev, deleted WERE NOT all valid tags
 * dev, PROD WERE NOT all valid tags
 * dev, PROD WERE all valid tags (case insensitive)
 */