alexwakeman/rules-runner

Business Rules Engine for Node

Introduction

rules-runner allows you to cleanly abstract your rules away from your application code

• run your dataset against a config JSON object
• results can modify your dataset or can return a new dataset of outcomes
• It's isomorphic and has minimal package dependencies - great for the browser and the server

Installation

npm install rules-runner

Examples

var Rules = require("rules-runner");

var config = {
  "Must be 16 or older if no adult is present": {
    //if all "tests" in the if statement match,
    if: {
      "person.age": {
        lessThan: 16
      },
      "person.adultPresent": false
    },
    //process all of the outcomes
    then: {
      "person.error": "Must be 16 or older if no adult is present",
      "errors.all[]": "person"
    }
  },
  "Must be employed": {
    if: {
      "company.isEmployed": false
    },
    then: {
      "company.error": "Must be employed",
      "errors.all[]": "company" //add [] to the end of a key to push values onto an array
    }
  };
};

var data = {
  person: {
    age: 15,
    adultPresent: false
  },
  company: {
    isEmployed: false
  }
};

var rules = new Rules(config);
rules.run(data);
assert.equal(data.person.error, "Must be 16 or older if no adult is present");
assert.equal(data.company.error, "Must be employed");
assert.deepEqual(data.errors.all, ["person", "company"]);
//by default, rules modify data object
//only want results leaving data unchanged? 
//var results = rules.run(data, {rulesModifyData: false});

#Also possible to test a series of if statements in an Array, as OR like conditionals

var config = {
    "Person will be in house if person is tired or hungry": {
            if: [
                {"person.tired": true},
                {"person.hungry": true}
            ],
            then: {
                "person.location": "house"
            }
        }
    };
    
var data = {
    person: {
        tired: false,
        hungry: true
    }
};

var rules = new Rules(config);
rules.run(data);

assert.equal(data.person.location, 'house');

#And if no conditions are true, then process an otherwise clause

var config = {
    "Person will be in house if person is tired or hungry": {
        if: [
            {"person.tired": true},
            {"person.hungry": true}
        ],
        then: {
            "person.location": "house"
        },
        otherwise: { // if all conditions are false
            "person.location": 'work'
        }
    }
};
var data = {
    person: {
        tired: false,
        hungry: false
    }
};

var rules = new Rules(config);
rules.run(data);

assert.equal(data.person.location, 'work');

Comparators/Tests

• between: "person.age": {between: [1, 20]} (note: this is exclusive of given values)
• equality/scalar values: "person.exists": true "person.firstName": "John"
• contains: `"person.name": {contains: "Jr"}`` (also checks for values in arrays)
• greaterThan: "person.age": {greaterThan: 20}
• in: "person.state": {in: ["CA", "TX", "NY"]}
• lessThan: "person.age": {lessThan: 21}
• matches: "person.name": {matches: "/(john|bob|mary)/i"}
• not: "person.state": {not: "CA"}, "person.state": {not: {in: ["CA", "TX"]}}

Options

• caseSensitive
  • default: true
  • contains and equals ignore case
• rulesModifyData
  • default: true
  • matching rules modify original data set rules.run() returns modified dataset
  • when false, rules create a new object, which gets returned
• strict
  • default: false
  • useful for debugging. when true, if a rule path (i.e. if: "person.age") isn't found in data, an error is thrown
  • when false, a rule path that isn't set in data evaluates to undefined
• stringNumbers:
  • default: true
  • greaterThan, lessThan, and between comparators will parse numbers. in will match with == instead of ===