/*
* This example demonstrates computing fact values at runtime, and leveraging the 'path' feature
* to select object properties returned by facts
*
* Usage:
* node ./examples/03-dynamic-facts.js
*
* For detailed output:
* DEBUG=json-rules-engine node ./examples/03-dynamic-facts.js
*/
require('colors')
let accountData = {
washington: {
company: 'microsoft',
status: 'terminated',
ptoDaysTaken: ['2016-12-25', '2016-04-01'],
createdAt: '2012-02-14'
},
jefferson: {
company: 'apple',
status: 'terminated',
ptoDaysTaken: ['2015-01-25'],
createdAt: '2005-04-03'
},
lincoln: {
company: 'microsoft',
status: 'active',
ptoDaysTaken: ['2016-02-21', '2016-12-25', '2016-03-28'],
createdAt: '2015-06-26'
}
}
/**
* mock api client for retrieving account information
*/
function getAccountInformation(accountId) {
var message = 'loading account information for "' + accountId + '"'
console.log(message.dim)
return new Promise((resolve, reject) => {
setImmediate(() => {
resolve(accountData[accountId])
})
})
}
let RuleEngine = require('json-rules-engine');
let engine = new RuleEngine.Engine();
require('colors')
// example client for making asynchronous requests to an api, database, etc
/**
* Setup a new engine
*/
/**
* Rule for identifying microsoft employees taking pto on christmas
*
* the account-information fact returns:
* { company: 'XYZ', status: 'ABC', ptoDaysTaken: ['YYYY-MM-DD', 'YYYY-MM-DD'] }
*/
let microsoftRule = {
conditions: {
all: [{
fact: 'account-information',
operator: 'equal',
value: 'microsoft',
path: '.company' // access the 'company' property of "account-information"
}, {
fact: 'account-information',
operator: 'in',
value: ['active', 'paid-leave'], // 'status'' can be active or paid-leave
path: '.status' // access the 'status' property of "account-information"
}, {
fact: 'account-information',
operator: 'contains',
value: '2016-12-25',
path: '.ptoDaysTaken' // access the 'ptoDaysTaken' property of "account-information"
}]
},
event: {
type: 'microsoft-christmas-pto',
params: {
message: 'current microsoft employee taking christmas day off'
}
}
}
engine.addRule(microsoftRule)
/**
* 'account-information' fact executes an api call and retrieves account data, feeding the results
* into the engine. The major advantage of this technique is that although there are THREE conditions
* requiring this data, only ONE api call is made. This results in much more efficient runtime performance.
*/
engine.addFact('account-information', function (params, almanac) {
return almanac.factValue('accountId')
.then(accountId => {
return getAccountInformation(accountId)
})
})
// define fact(s) known at runtime
let facts = { accountId: 'lincoln' }
engine
.run(facts)
.then(events => {
if (!events.length) return
console.log(facts.accountId + ' is a ' + events.map(event => event.params.message))
})
.catch(err => console.log(err.stack))
/*
* OUTPUT:
*
* loading account information for "lincoln"
* lincoln is a current microsoft employee taking christmas day off
*
* NOTES:
*
* - Notice that although all 3 conditions required data from the "account-information" fact,
* the account-information api call is executed only ONCE. This is because fact results are
* cached by default, increasing performance and lowering network requests.
*
* - See the 'fact' docs on how to disable fact caching
*/
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