Plain Rules Engine

Introduction

Plain Rules Engine is a TypeScript library for creating and evaluating simple business rules in Node.js applications. It provides a flexible way to define and apply rules to your data.

Features

Easy rule creation and evaluation. Defining a rule in JSON is as simple as:

{
    "trackHasStrongLanguage": {
        "conditions": [
            ["$.user.age", "lessThan", 16],
            ["$.tags", "contains", "strong language"]
        ],
        "effect": {
            "action": "omit"
        }
    },
  ... other rules
}

You can also define rules in TypeScript:

export const musicSearchRules: Rule = {
  trackHasStrongLanguage: {
    conditions: [
      ['$.user.age', Operator.LESS_THAN, 16],
      ['$.tags', Operator.CONTAINS, 'strong language'],
    ],
    effect: {
      action: Action.OMIT,
    },
  },
  // Add more rules here
};

In this case, the effect defined for "trackHasStrongLanguage" will only be applied to objects that meet all conditions in conditions array

Customizable rule actions and conditions.
Written in TypeScript for type safety.

Installation

You can install Plain Rules Engine via npm:

npm install plain-rules-engine

Usage

Here's an example of how to use Plain Rules Engine:

import {
  RuleEngine,
  type Rule,
  type ApplyRulesResponse,
} from 'plain-rules-engine';

// Define your rules (could be in a JSON file, TS file, an object store, in-memory database etc.). See example rule definition above

// Fetch your rules (you'll have to create the function that does that)
const musicSearchRules: Rule = fetchRulesFromDataSource();

// Instantiate the rule engine
const engine = new RuleEngine(musicSearchRules);

// Define your data
const tracks = [
  {
    title: 'Heal the World',
    artist: 'Michael Jackson',
    year: 1991,
    album: 'Dangerous',
    tags: ['pop', 'society'],
  },
  {
    title: 'The Girl From Last Night',
    artist: 'Jackson Pepper',
    year: 2017,
    album: 'Slot Machine',
    tags: ['rap', 'strong language'],
  },
];

const user = {
  user: {
    age: 14,
    lastLogin: '2023-08-26T16:00:45Z',
  },
};

// Apply the rules
const evaluation = engine.applyRules(tracks, user);

// Handle the results
console.log('RESULT: ', evaluation);

For more detailed documentation and examples, please refer to Building a Rule Engine With TypeScript — the article that inspired Plain Rules Engine.

Contribution

We welcome contributions from the community. If you'd like to contribute to this project or have any questions, issues, or suggestions, please feel free to open an issue.

License

This project is licensed under the Apache-2.0 License.