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@aipeel/json-rules-engine

v1.0.1

Published

## What does it do? Pass a Rule and Data to engine and get a synchronous response on whether the Data satisfies the Rules.

Downloads

17

Readme

JSON Rule Engine

What does it do?

Pass a Rule and Data to engine and get a synchronous response on whether the Data satisfies the Rules.

@aipeel/json-rules-engine

Installation

    npm install @aipeel/json-rules-engine

Usage

Step 1: Define Rules JSON

  1. Rules JSON must be an object

  2. Must start with AND or OR which takes array of rule

    1. Single Rule Criteria
    {
        AND: [ Criteria1 ]
    }
    1. Multiple Rule Criteria --> Criteria 1 and 2 must be satisfied
    {
        AND: [ Criteria1, Criteria2 .. ]
    }
    1. Multiple Levels of Rules --> Criteria 1 & 2 must be satisfied and either Criteria3 or Criteria4 must be satisfied
    {
        AND: [
                {
                    AND: [ Criteria1, Criteria2 ...]
                },
                {
                    OR: [Criteria3, Criteria4 ..]
                }
            ]
    }
  3. Each Criteria must be an object

    1. The key in criteria is an operator and value defines the metadata required for the operator to workExamples of Criteria

      { 
          "between": { 
                          "min": "10", 
                          "max": "20", 
                          "attribute": "discount" 
                      }
      }
      { 
          "in": { 
                  "value": ["C","Javascript","Python"], 
                  "attribute": "lang"
              }
      }
    2. List of all criteria given below

      | Operator | Operator Property | Description | Example | | |------------------|---------------------|--------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------|---| | between | min, max, attribute | Check if the property mentioned in attribute has value between min and max | { "between" : { "min" : "10" , "max" : "20" , "attribute" : "discount" }} | | | lessThan | value, attribute | Check if the property mentioned in attribute has number less than value | { "lessThan" : { "value" : "80" , "attribute" : "price" } } | | | lessThanEqual | value, attribute | Check if the property mentioned in attribute has number less than or equal value | { "lessThanEqual" : { "value" : "80" , "attribute" : "price" } } | | | greaterThan | value, attribute | Check if the property mentioned in attribute has number greater than value | { "greaterThan" : { "value" : "80" , "attribute" : "price" } } | | | greaterThanEqual | value, attribute | Check if the property mentioned in attribute has number greater than or equal value | { "greaterThanEqual" : { "value" : "80" , "attribute" : "price" } } | | | equal | value, attribute | Check if the property mentioned in attribute has value equal to value provided | { "equal" : { "value" : "80" , "attribute" : "price" } } | | | contains | value, attribute | Check if the property mentioned in attribute contains the value given. | { "contains" : { "value" : "great" , "attribute" : "desc" }} | | | in | value, attribute | Check if the property mentioned in attribute is available in value array provided. | { "in" : { "value" : [ "C" , "Javascript" , "Python" ], "attribute" : "lang" }} | |

    3. A Rules JSON could be defined as

    { 
        "AND": [
            { "lessThan": {"value": "80", "attribute": "price"} },
            { "greaterThanEqual": {"value": "20", "attribute": "price"} },
            { "between": { "min": "10", "max": "20", "attribute": "discount" }}
        ]
    }
    {
        "OR":[
            { "contains": { "value": "great", "attribute": "desc" }},
            { "contains": { "value": "works", "attribute": "features"}},
            { "in": { "value": ["C","Javascript","Python"], "attribute": "lang"}},
        ]
    }
  4. Rules can be recursively nested as shown below

    {
        "AND": [
                { 
                    "AND": [
                        { "lessThan": {"value": "80", "attribute": "price"} },
                        { "greaterThanEqual": {"value": "20", "attribute": "price"} },
                        { "between": { "min": "10", "max": "20", "attribute": "discount" }}
                    ]
                },
                {
                    "OR":[
                        { "contains": { "value": "great", "attribute": "desc" }},
                        { "contains": { "value": "works", "attribute": "features"}},
                        { "in": { "value": ["C","Javascript","Python"], "attribute": "lang"}},
                    ]
                }
            ]
    }

Step2: Pass Data JSON and Rule JSON to Engine

    const Engine = require("@aipeel/json-rules-engine")

    Engine.apply(data,rule) // returns boolean - true or false

Complete end-to-end example below for reference

const Engine = require("@aipeel/json-rules-engine")

const rule = {
                    "AND": [
                            { 
                                "AND": [
                                    { "lessThan": {"value": "80", "attribute": "price"} },
                                    { "greaterThanEqual": {"value": "20", "attribute": "price"} },
                                    { "between": { "min": "10", "max": "20", "attribute": "discount" }}
                                ]
                            },
                            {
                                "OR":[
                                    { "contains": { "value": "great", "attribute": "desc" }},
                                    { "contains": { "value": "works", "attribute": "features"}},
                                    { "in": { "value": ["C","Javascript","Python"], "attribute": "lang"}},
                                ]
                            }
                        ]
                    }

let data = {
    id: 'ID1001',
    price: 50,
    discount: 10,
    desc: "This is a great product for developers",
    features: ["No Dependencies", "Open to Extension", "Synchronous", "works"],
    tags: ["json", "rule", "engine"],
    lang: "Javascript"
}

// example 1
console.log(`Does the data conform to rule? --> ${Engine.apply(data,rule)?"Yes":"No"}`);

//example 2
data.price = 100;
console.log(`Does the data conform to rule? --> ${Engine.apply(data,rule)?"Yes":"No"}`);

//example 3
data.price = 50;
data.discount = 21;
console.log(`Does the data conform to rule? --> ${Engine.apply(data,rule)?"Yes":"No"}`);

Output

Does the data conform to rule? --> Yes
Does the data conform to rule? --> No
Does the data conform to rule? --> No