Getting Started

Installation

Install the package via NuGet:

dotnet add package EasyDecisions

Basic Example

Let's define a simple decision that determines if a user is eligible for a discount based on their cart total and membership status.

1. Define your Input and Output

public record CartInput(decimal Total, bool IsPremiumMember);
public record DiscountOutput(decimal DiscountPercentage);

2. Build the Decision

The recommended way to define rules is by inheriting from Decision<TInput, TOutput>. This keeps your business logic clean and isolated.

using EasyDecisions;

public class DiscountDecision : Decision<CartInput, DiscountOutput>
{
    public DiscountDecision() : base("CartDiscount")
    {
        // Premium members spending over $100 get 20% off
        When(i => i.IsPremiumMember && i.Total > 100)
            .Then()
            .Set(o => o.DiscountPercentage = 20m);

        // Regular members spending over $100 get 10% off
        When(i => !i.IsPremiumMember && i.Total > 100)
            .Then()
            .Set(o => o.DiscountPercentage = 10m);
    }
}

3. Evaluate

To evaluate your decision, use the EasyDecision.Evaluate helper. The input type is automatically inferred, and the result is type-safe:

var input = new CartInput(150, true);
var result = EasyDecision.Evaluate<DiscountDecision>(input);

Console.WriteLine($"Discount: {result.DiscountPercentage}%"); // Output: Discount: 20%

With just a few lines of code, you have a fully functional, type-safe decision engine!