144 lines
4.1 KiB
Markdown
144 lines
4.1 KiB
Markdown
## Description
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RulesEngine is a highly extensible library to build rule based system using C# expressions
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## Features
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- Json based rules defination
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- Multiple input support
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- Dynamic object input support
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- C# Expression support
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- Extending expression via custom class/type injection
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- Scoped parameters
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- Post rule execution actions
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## Installation
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Nuget package: [](https://www.nuget.org/packages/RulesEngine/)
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## Basic Usage
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### Create a workflow file with rules
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```json
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[
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{
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"WorkflowName": "Discount",
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"Rules": [
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{
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"RuleName": "GiveDiscount10",
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"Expression": "input1.country == \"india\" AND input1.loyalityFactor <= 2 AND input1.totalPurchasesToDate >= 5000 AND input2.totalOrders > 2 AND input3.noOfVisitsPerMonth > 2"
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},
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{
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"RuleName": "GiveDiscount20",
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"Expression": "input1.country == \"india\" AND input1.loyalityFactor == 3 AND input1.totalPurchasesToDate >= 10000 AND input2.totalOrders > 2 AND input3.noOfVisitsPerMonth > 2"
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}
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]
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}
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]
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```
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### Initialise RulesEngine with the workflow:
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```c#
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var workflowRules = //Get list of workflow rules declared in the json
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var re = new RulesEngine.RulesEngine(workflowRules, null);
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```
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### Execute the workflow rules with input:
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```c#
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// Declare input1,input2,input3
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var resultList = await re.ExecuteAllRulesAsync("Discount", input1,input2,input3);
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//Check success for rule
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foreach(var result in resultList){
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Console.WriteLine($"Rule - {result.Rule.RuleName}, IsSuccess - {result.IsSuccess}");
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}
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```
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This will execute all the rules under `Discount` workflow and return ruleResultTree for all rules
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**Note: input passed to rulesEngine can be of a concrete type, an anonymous type or dynamic(Expandobject). In case of dynamic object, RulesEngine will internally convert to an anonymous type**
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### Using custom names for inputs
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By Default, RulesEngine will name the inputs as input1, input2, input3... respectively.
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It is possible to use a custom name in rules by passing input as `RuleParameter`
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```json
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[
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{
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"WorkflowName": "DiscountWithCustomInputNames",
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"Rules": [
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{
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"RuleName": "GiveDiscount10",
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"Expression": "basicInfo.country == \"india\" AND basicInfo.loyalityFactor <= 2 AND basicInfo.totalPurchasesToDate >= 5000 AND orderInfo.totalOrders > 2 AND telemetryInfo.noOfVisitsPerMonth > 2"
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},
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{
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"RuleName": "GiveDiscount20",
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"Expression": "basicInfo.country == \"india\" AND basicInfo.loyalityFactor == 3 AND basicInfo.totalPurchasesToDate >= 10000 AND orderInfo.totalOrders > 2 AND telemetryInfo.noOfVisitsPerMonth > 2"
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}
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]
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}
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]
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```
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Now we can call rulesEngine with the custom names:
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```c#
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var workflowRules = //Get list of workflow rules declared in the json
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var re = new RulesEngine.RulesEngine(workflowRules, null);
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// Declare input1,input2,input3
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var rp1 = new RuleParameter("basicInfo",input1);
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var rp2 = new RuleParameter("orderInfo", input2);
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var rp3 = new RuleParameter("telemetryInfo",input3);
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var resultList = await re.ExecuteAllRulesAsync("DiscountWithCustomInputNames",rp1,rp2,rp3);
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```
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## ScopedParams
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Sometimes Rules can get very long and complex, scopedParams allow users to replace an expression in rule with an alias making it easier to maintain rule.
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RulesEngine supports two type of ScopedParams:
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- GlobalParams
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- LocalParams
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### GlobalParams
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GlobalParams are defined at workflow level and can be used in any rule.
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#### Example
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```json
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//Rule.json
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{
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"WorkflowName": "workflowWithGlobalParam",
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"GlobalParams":[
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{
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"Name":"myglobal1",
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"Expression":"myInput.hello.ToLower()"
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}
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],
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"Rules":[
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{
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"RuleName": "checkGlobalEqualsHello",
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"Expression":"myglobal1 == \"hello\""
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},
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{
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"RuleName": "checkGlobalEqualsInputHello",
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"Expression":"myInput.hello.ToLower() == myglobal1"
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}
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]
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}
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```
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These rules when executed with the below input will return success
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```c#
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var input = new RuleParameter("myInput",new {
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hello = "HELLO"
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});
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var resultList = await re.ExecuteAllRulesAsync("workflowWithGlobalParam",rp);
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```
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