Async process inside success event
See original GitHub issueI’m having some trouble leveraging rule-chaining to add some runtime facts based on facts already in the Almanac like described here https://github.com/CacheControl/json-rules-engine/blob/master/docs/almanac.md#retrieve-fact-values-when-handling-events
I’ve modified https://github.com/CacheControl/json-rules-engine/blob/master/examples/07-rule-chaining.js to provide an primitive example of what I’m trying to do
/*
* This is an advanced example demonstrating rules that passed based off the
* results of other rules by adding runtime facts. It also demonstrates
* accessing the runtime facts after engine execution.
*
* Usage:
* node ./examples/07-rule-chaining.js
*
* For detailed output:
* DEBUG=json-rules-engine node ./examples/07-rule-chaining.js
*/
require('colors');
const { Engine } = require('../dist').Engine
/**
* Setup a new engine
*/
const engine = new Engine();
/**
* Rule for identifying people who may like screwdrivers
*/
const drinkRule = {
conditions: {
all: [
{
fact: 'drinksOrangeJuice',
operator: 'equal',
value: true,
},
{
fact: 'enjoysVodka',
operator: 'equal',
value: true,
},
],
},
event: { type: 'drinks-screwdrivers' },
priority: 10, // IMPORTANT! Set a higher priority for the drinkRule, so it runs first
};
engine.addRule(drinkRule);
/**
* Register listeners with the engine for rule success and failure
*/
let facts;
engine
.on('success', async (event, almanac) => {
console.log(`${facts.accountId + ' DID '.green}meet conditions for the ${event.type.underline} rule.`);
return new Promise((resolve) => {
setTimeout(() => {
console.log('promise resolved');
resolve();
}, 0);
});
})
.on('failure', (event) => {
console.log(`${facts.accountId} did ${'NOT'.red} meet conditions for the ${event.type.underline} rule.`);
});
// define fact(s) known at runtime
facts = {
accountId: 'washington',
drinksOrangeJuice: true,
enjoysVodka: true,
isSociable: true,
};
engine
.run(facts) // first run, using washington's facts
.then(() => {
console.log('engine run completed');
})
.catch();
/*
* OUTPUT:
*
* washington DID meet conditions for the drinks-screwdrivers rule.
* engine run completed
* promise resolved
*/
I would expect the success event to complete before the engine run finishes like so:
/*
* OUTPUT:
*
* washington DID meet conditions for the drinks-screwdrivers rule.
* promise resolved
* engine run completed
*/
Here’s a more concrete example based on my use case. I’m reading some facts from the Almanac, and I plan to assign a runtime fact based on those values.
const { Engine } = require('../dist').Engine
/**
* Setup a new engine
*/
require('colors');
const engine = new Engine();
/**
* Rule for identifying people who may like screwdrivers
*/
const drinkRule = {
conditions: {
all: [
{
fact: 'drinksOrangeJuice',
operator: 'equal',
value: true,
},
{
fact: 'enjoysVodka',
operator: 'equal',
value: true,
},
],
},
event: { type: 'drinks-screwdrivers' },
priority: 10, // IMPORTANT! Set a higher priority for the drinkRule, so it runs first
};
engine.addRule(drinkRule);
/**
* Register listeners with the engine for rule success and failure
*/
let facts;
engine
.on('success', async (event, almanac) => {
almanac.addRuntimeFact('screwdriverAficionado', true);
console.log(`${facts.accountId + ' DID '.green}meet conditions for the ${event.type.underline} rule.`);
let someInput;
someInput = await almanac.factValue('someInput');
someInput = await almanac.factValue('someInput');
someInput = await almanac.factValue('someInput');
someInput = await almanac.factValue('someInput');
someInput = await almanac.factValue('someInput');
someInput = await almanac.factValue('someInput');
someInput = await almanac.factValue('someInput');
someInput = await almanac.factValue('someInput');
someInput = await almanac.factValue('someInput');
almanac.addRuntimeFact(`newFact`, someInput);
console.log('resolved input', someInput);
})
.on('failure', (event) => {
console.log(`${facts.accountId} did ${'NOT'.red} meet conditions for the ${event.type.underline} rule.`);
});
// define fact(s) known at runtime
facts = {
accountId: 'washington',
drinksOrangeJuice: true,
enjoysVodka: true,
isSociable: true,
someInput: [1, 2, 3],
};
engine
.run(facts)
.then((results) => {
console.log('engine run completed');
// console.log(results);
})
.catch();
/*
* OUTPUT:
*
* washington DID meet conditions for the drinks-screwdrivers rule.
* engine run completed
* resolved input [ 1, 2, 3 ]
*/
And if I remove some of those async processes, then I get my expected behavior
...
engine
.on('success', async (event, almanac) => {
almanac.addRuntimeFact('screwdriverAficionado', true);
console.log(`${facts.accountId + ' DID '.green}meet conditions for the ${event.type.underline} rule.`);
let someInput;
someInput = await almanac.factValue('someInput');
almanac.addRuntimeFact(`newFact`, someInput);
console.log('resolved input', someInput);
})
...
/*
* OUTPUT:
*
* washington DID meet conditions for the drinks-screwdrivers rule.
* resolved input [ 1, 2, 3 ]
* engine run completed
*/
Issue Analytics
- State:
- Created 3 years ago
- Comments:6 (4 by maintainers)
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I’ve taken a crack at this in #237 - relatively easy fix since EventEmitter2 supports this out of the box. Comments welcome. I still have some docs to write and examples to tweak, but I think this is functionally code complete. Since this is a breaking change, I’ve got at least 1 other breaking change I’d like to into into this next release, so I’m shooting for a release in the next two weeks.
@iamzoh @naveen-shetty if you’d like to confirm the fix, you can
npm install json-rules-engine@6.0.0-alpha-3
.This feature is now available in v6.0.0. See changelog