This project inspired originally from json-rules-engine project. Even there are many similarities, This is not a complete PORT of 'json-rules-engine' Still has lots of works to do. Feel free to make contribitions.
Install using the JsonRulesEngine NuGet package:
dotnet add package JsonRulesEngine --version 0.0.1
var incomingJson= `{
"age": 19,
"line-item-names": [
"banana",
"apple"
],
"amount":300
}`
var engine = new Engine();
engine.AddRule(ruleJson);// checkout Rules section
var events = e.Execute(incomingJson);
foreach (var @event in events)
{
if (@event is DiscountEvent)
{
var discountEvent = (DiscountEvent)@event;
Console.WriteLine("DiscountEvent with amount : {0}", discountEvent.amount);
}
}Rule is a json object it contains two main properties. conditions and event
//If age is above 18 and total transaction amount is less than 1000 and ('line-item-names' list contains 'banana' or 'amount' is in range (50,300])
{
"conditions": {
"all": [
{
"fact": "age",
"operator": "greaterThan",
"value": 18
},
{
"fact":"total-transaction-amount",//DynamicFact
"params":{
"startDate":"2020-12-12T10:00:00",
"endDate":"2021-12-12T10:00:00",
},
"operator":"lessThan",
"value":1000
},
{
"any": [
{
"fact": "line-item-names",
"operator": "contain",
"value": "banana"
},
{
"fact": "amount",
"operator": "in-range",//CustomOperator
"value": [50,300]
}
]
}
]
},
"event": {
"type": "discount",
"amount": 100
}
}Engine has couple of default operators:
equalmakes string comparisongreaterThanfloat comparisongreaterThanInclusivefloat comparisonlessThanfloat comparisonlessThanThanInclusivefloat comparisoninstring array comparisoncontainstring array comparison
You could also define your custom operators like following. Declare a type inherited from Operator<L,R>, engine will resolve it automatically.
public class InRange : Operator<float, List<float>>
{
public override string Name => "in-range";
public override bool Evaluate(float left, List<float> right) // range(1,3]
{
float upperBound = right.Last();
float lowerBound = right.First();
if (left > lowerBound && left <= upperBound)
{
return true;
}
return false;
}
}If your incomingJson unable to contain certain information. You can inherit a class from DynamicFact to achive this. declare it anywhere you want. engine will resolve it for you.
Example total-transcation-amount:
public class TotalTransactionAmount : DynamicFact
{
public override string Name => "total-transaction-amount";
public override object Calculate(ExecutionContext context, dynamic @params)
{
var productToken = context.FactValue("products");//able to get fact value from context
//it will not compute if fact value if it has already computed beforehand
var products = productToken.ToObject<List<string>>();
DateTime startDate = @params["startDate"];
DateTime endDate = @params["endDate"];
// go anywhere you want
return 100;
}
}Engine should know the type of an RuleEvent in order to cast it to an instane.
Just inherit a class from RuleEvent, engine will resolve types from assembly.
public class DiscountEvent : RuleEvent
{
public override string Name => "discount";
public float amount;
}- Fact priorities
- Rule priorities
- Unit Tests
- Documentation
- Nuget Package
- CD/CI
- Async Execution and Event Handles