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https://github.com/timophe-91/rulesengine

A Json based Rules Engine with extensive Dynamic expression support
https://github.com/timophe-91/rulesengine

bre business dotnet engine expression-evaluatior nuget rules rules-engine workflow

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A Json based Rules Engine with extensive Dynamic expression support

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[download-image]: https://img.shields.io/nuget/dt/timophe.RulesEngine



[download-url]: https://www.nuget.org/packages/timophe.RulesEngine/



# Rules Engine ##



NOTICE: This is a FORK of [microsoft/RulesEngine]( https://github.com/microsoft/RulesEngine)



This fork will develop detached from the original project.



## Now with Interface



I added Interfaces for Rule and Workflow, to easier customize the behaviour of the rule to personal needs. Tried to not

do breaking changes.



## Roadmap



This is the Roadmap of this RulesEngine fork.



- Add Event to OnFailed

- Enhance and Correct the Wiki

- Add LogicalRule and LeafRule as classes for easier use

- Add AI Support for the RulesEngine (OpenAI and Google probably)



Somewhat later:

Probably breaking changes:

- Migrate from Newtonsoft.Json to System.Text.Json



## Overview



Rules Engine is a library/NuGet package for abstracting business logic/rules/policies out of a system. It provides a

simple way of giving you the ability to put your rules in a store outside the core logic of the system, thus ensuring

that any change in rules don't affect the core system.



## Installation



To install this library, download the latest version

of [NuGet Package](https://www.nuget.org/packages/timophe.RulesEngine/) from [nuget.org](https://www.nuget.org/) and

refer it into your project.



## How to use it



There are several ways to populate workflows for the Rules Engine as listed below.



You need to store the rules based on

the [schema definition](https://github.com/timophe-91/RulesEngine/blob/main/schema/workflow-schema.json) given, and they

can be stored in any store as deemed appropriate like Azure Blob Storage, Cosmos DB, Azure App

Configuration, [Entity Framework](https://github.com/timophe-91/RulesEngine#entity-framework), SQL Servers, file systems

etc. For RuleExpressionType `LambdaExpression`, the rule is written as

a [lambda expressions](https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/statements-expressions-operators/lambda-expressions).



An example rule:



```json

[

  {

    "WorkflowName": "Discount",

    "Rules": [

      {

        "RuleName": "GiveDiscount10",

        "SuccessEvent": "10",

        "ErrorMessage": "One or more adjust rules failed.",

        "ErrorType": "Error",

        "RuleExpressionType": "LambdaExpression",

        "Expression": "input1.country == \"india\" AND input1.loyaltyFactor <= 2 AND input1.totalPurchasesToDate >= 5000"

      },

      {

        "RuleName": "GiveDiscount20",

        "SuccessEvent": "20",

        "ErrorMessage": "One or more adjust rules failed.",

        "ErrorType": "Error",

        "RuleExpressionType": "LambdaExpression",

        "Expression": "input1.country == \"india\" AND input1.loyaltyFactor >= 3 AND input1.totalPurchasesToDate >= 10000"

      }

    ]

  }

]

```



You can inject the rules into the Rules Engine by initiating an instance by using the following code -



```c#

var rulesEngine = new RulesEngine(workflow);

```



Here, *workflow* is a list of deserialized objects based on the schema explained above

Once initialised, the Rules Engine needs to execute the rules for a given input. This can be done by calling the

method `ExecuteAllRulesAsync`:



```c#

List response = await rulesEngine.ExecuteAllRulesAsync(workflowName, input);

```



Here, *workflowName* is the name of the workflow, which is *Discount* in the above-mentioned example. And *input* is the

object which needs to be checked against the rules, which itself may consist of a list of class instances.



The *response* will contain a list of [

*RuleResultTree*](https://github.com/timophe-91/RulesEngine/wiki/Getting-Started#ruleresulttree) which gives information

if a particular rule passed or failed.



_A demo app for the is available at [this location](https://github.com/timophe-91/RulesEngine/tree/main/demo)._



## Basic



A simple example via code only is as follows:



```c#

List rules = new List();



Rule rule = new Rule();

rule.RuleName = "Test Rule";

rule.SuccessEvent = "Count is within tolerance.";

rule.ErrorMessage = "Over expected.";

rule.Expression = "count < 3";

rule.RuleExpressionType = RuleExpressionType.LambdaExpression;

rules.Add(rule);



var workflows = new List();



Workflow exampleWorkflow = new Workflow();

exampleWorkflow.WorkflowName = "Example Workflow";

exampleWorkflow.Rules = rules;



workflows.Add(exampleWorkflow);



var bre = new RulesEngine.RulesEngine(workflows.ToArray());

```



## Entity Framework



Consuming Entity Framework and populating the Rules Engine is shown in

the [EFDemo class](https://github.com/microsoft/RulesEngine/blob/main/demo/DemoApp/EFDemo.cs) with Workflow rules

populating the array and passed to the Rules Engine, The Demo App includes an

example [RulesEngineDemoContext](https://github.com/microsoft/RulesEngine/blob/main/demo/DemoApp.EFDataExample/RulesEngineDemoContext.cs)

using SQLite and could be swapped out for another provider.



```c#

var wfr = db.Workflows.Include(i => i.Rules).ThenInclude(i => i.Rules).ToArray();

var bre = new RulesEngine.RulesEngine(wfr, null);

```



*Note: For each level of nested rules expected, a ThenInclude query appended will be needed as shown above.*



## How it works



![](https://github.com/timophe-91/RulesEngine/blob/main/assets/BlockDiagram.png)



The rules can be stored in any store and be fed to the system in a structure which adheres to

the [schema](https://github.com/timophe-91/RulesEngine/blob/main/schema/workflow-schema.json) of WorkFlow model.



A wrapper needs to be created over the Rules Engine package, which will get the rules and input message(s) from any

store that your system dictates and put it into the Engine. The wrapper then handles the output using appropriate means.



_Note: To know in detail of the workings of Rules Engine, please

visit [How it works section](https://github.com/timophe-91/RulesEngine/wiki/Introduction#how-it-works)

in [Rules Engine Wiki](https://github.com/timophe-91/RulesEngine/wiki)._



## Contributing



This project welcomes contributions and suggestions. Most contributions require you to agree to a

Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us

the rights to use your contribution.



---



_For more details please check out [Rules Engine Wiki](https://github.com/timophe-91/RulesEngine/wiki)._