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| 1 | + 'use strict' | ||
| 2 | + | ||
| 3 | + /* | ||
| 4 | + * This is a basic example demonstrating how to leverage the metadata supplied by rule results | ||
| 5 | + * | ||
| 6 | + * Usage: | ||
| 7 | + * node ./examples/09-rule-results.js | ||
| 8 | + * | ||
| 9 | + * For detailed output: | ||
| 10 | + * DEBUG=json-rules-engine node ./examples/09-rule-results.js | ||
| 11 | + */ | ||
| 12 | + require('colors') | ||
| 13 | + let Engine = require('../dist').Engine | ||
| 14 | + | ||
| 15 | + /** | ||
| 16 | + * Setup a new engine | ||
| 17 | + */ | ||
| 18 | + let engine = new Engine() | ||
| 19 | + | ||
| 20 | + // rule for determining honor role student atheletes (student has GPA >= 3.5 AND is an athlete) | ||
| 21 | + engine.addRule({ | ||
| 22 | + conditions: { | ||
| 23 | + all: [{ | ||
| 24 | + fact: 'athlete', | ||
| 25 | + operator: 'equal', | ||
| 26 | + value: true | ||
| 27 | + }, { | ||
| 28 | + fact: 'GPA', | ||
| 29 | + operator: 'greaterThanInclusive', | ||
| 30 | + value: 3.5 | ||
| 31 | + }] | ||
| 32 | + }, | ||
| 33 | + event: { // define the event to fire when the conditions evaluate truthy | ||
| 34 | + type: 'honor-roll', | ||
| 35 | + params: { | ||
| 36 | + message: 'Student made the athletics honor-roll' | ||
| 37 | + } | ||
| 38 | + } | ||
| 39 | + }) | ||
| 40 | + | ||
| 41 | + function render (message, ruleResult) { | ||
| 42 | + // if rule succeeded, render success message | ||
| 43 | + if (ruleResult.result) { | ||
| 44 | + return console.log(`${message}`.green) | ||
| 45 | + } | ||
| 46 | + // if rule failed, iterate over each failed condition to determine why the student didn't qualify for athletics honor roll | ||
| 47 | + let detail = ruleResult.conditions.all.filter(condition => !condition.result) | ||
| 48 | + .map(condition => { | ||
| 49 | + switch (condition.operator) { | ||
| 50 | + case 'equal': | ||
| 51 | + return `was not an ${condition.fact}` | ||
| 52 | + case 'greaterThanInclusive': | ||
| 53 | + return `${condition.fact} of ${condition.factResult} was too low` | ||
| 54 | + } | ||
| 55 | + }).join(' and ') | ||
| 56 | + console.log(`${message} ${detail}`.red) | ||
| 57 | + } | ||
| 58 | + | ||
| 59 | + /** | ||
| 60 | + * On success, retrieve the student's username for display purposes, and render | ||
| 61 | + */ | ||
| 62 | + engine.on('success', (event, almanac, ruleResult) => { | ||
| 63 | + almanac.factValue('username').then(username => { | ||
| 64 | + render(`${username.bold} succeeded! ${event.params.message}`, ruleResult) | ||
| 65 | + }) | ||
| 66 | + }) | ||
| 67 | + | ||
| 68 | + /** | ||
| 69 | + * On failure, retrieve the student's username for display purposes, and render | ||
| 70 | + */ | ||
| 71 | + engine.on('failure', (event, almanac, ruleResult) => { | ||
| 72 | + almanac.factValue('username').then(username => { | ||
| 73 | + render(`${username.bold} failed - `, ruleResult) | ||
| 74 | + }) | ||
| 75 | + }) | ||
| 76 | + | ||
| 77 | + // Run the engine for 5 different students | ||
| 78 | + Promise.all([ | ||
| 79 | + engine.run({ athlete: false, GPA: 3.9, username: 'joe' }), | ||
| 80 | + engine.run({ athlete: true, GPA: 3.5, username: 'larry' }), | ||
| 81 | + engine.run({ athlete: false, GPA: 3.1, username: 'jane' }), | ||
| 82 | + engine.run({ athlete: true, GPA: 4.0, username: 'janet' }), | ||
| 83 | + engine.run({ athlete: true, GPA: 1.1, username: 'sarah' }) | ||
| 84 | + ]) | ||
| 85 | + | ||
| 86 | + /* | ||
| 87 | + * OUTPUT: | ||
| 88 | + * | ||
| 89 | + * joe failed - was not an athlete | ||
| 90 | + * larry succeeded! Student made the athletics honor-roll | ||
| 91 | + * jane failed - was not an athlete and GPA of 3.1 was too low | ||
| 92 | + * janet succeeded! Student made the athletics honor-roll | ||
| 93 | + * sarah failed - GPA of 1.1 was too low | ||
| 94 | + */ | ||
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