/*
* This is an advanced example that demonstrates facts with dependencies
* on other facts. In addition, it demonstrates facts that load data asynchronously
* from outside sources (api's, databases, etc)
*
* Usage:
* node ./examples/04-fact-dependency.js
*
* For detailed output:
* DEBUG=json-rules-engine node ./examples/04-fact-dependency.js
*/
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();
/**
* Setup a new engine
*/
/**
* Rule for identifying microsoft employees that have been terminated.
* - Demonstrates re-using a same fact with different parameters
* - Demonstrates calling a base fact, which serves to load data once and reuse later
*/
let microsoftRule = {
conditions: {
all: [{
fact: 'account-information',
operator: 'equal',
value: 'microsoft',
path: '.company'
}, {
fact: 'account-information',
operator: 'equal',
value: 'terminated',
path: '.status'
}]
},
event: { type: 'microsoft-terminated-employees' }
}
engine.addRule(microsoftRule)
/**
* Rule for identifying accounts older than 5 years
* - Demonstrates calling a base fact, also shared by the account-information-field fact
* - Demonstrates performing computations on data retrieved by base fact
*/
let tenureRule = {
conditions: {
all: [{
fact: 'employee-tenure',
operator: 'greaterThanInclusive',
value: 5,
params: {
'unit': 'years'
}
}]
},
event: { type: 'five-year-tenure' }
}
engine.addRule(tenureRule)
/**
* Register listeners with the engine for rule success and failure
*/
let facts
engine
.on('success', event => {
console.log(facts.accountId + ' DID '.green + 'meet conditions for the ' + event.type.underline + ' rule.')
})
.on('failure', event => {
console.log(facts.accountId + ' did ' + 'NOT'.red + ' meet conditions for the ' + event.type.underline + ' rule.')
})
/**
* 'account-information' fact executes an api call and retrieves account data
* - Demonstrates facts called only by other facts and never mentioned directly in a rule
*/
engine.addFact('account-information', (params, almanac) => {
return almanac.factValue('accountId')
.then(accountId => {
return getAccountInformation(accountId)
})
})
/**
* 'employee-tenure' fact retrieves account-information, and computes the duration of employment
* since the account was created using 'accountInformation.createdAt'
*/
engine.addFact('employee-tenure', (params, almanac) => {
return almanac.factValue('account-information')
.then(accountInformation => {
let created = new Date(accountInformation.createdAt)
let now = new Date()
switch (params.unit) {
case 'years':
return now.getFullYear() - created.getFullYear()
case 'milliseconds':
default:
return now.getTime() - created.getTime()
}
})
.catch(console.log)
})
// define fact(s) known at runtime
facts = { accountId: 'washington' }
engine
.run(facts) // first run, using washington's facts
.then(() => {
facts = { accountId: 'jefferson' }
return engine.run(facts) // second run, using jefferson's facts; facts & evaluation are independent of the first run
})
.catch(console.log)
/*
* OUTPUT:
*
* loading account information for "washington"
* washington DID meet conditions for the microsoft-terminated-employees rule.
* washington did NOT meet conditions for the five-year-tenure rule.
* loading account information for "jefferson"
* jefferson did NOT meet conditions for the microsoft-terminated-employees rule.
* jefferson DID meet conditions for the five-year-tenure rule.
*/
/*
* NOTES:
*
* - Notice that although a total of 6 conditions were evaluated using
* account-information (3 rule conditions x 2 accounts), the account-information api call
* is only called twice -- once for each account. This is due to the base fact caching the results
* for washington and jefferson after the initial data load.
*/
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