What is EasyDecisions?

EasyDecisions is a lightweight, fluent decision engine for .NET, built as an alternative to complex Decision Model and Notation (DMN) engines like Camunda.

The Pain Points of DMN

Traditional DMN engines force you to define your business rules in external XML files. While powerful, this approach has significant drawbacks:

• No Compile-Time Safety: Typos in variable names aren't caught until your app runs.
• Hard to Refactor: Renaming a property in C# breaks the DMN file unless manually updated.
• Context Switching: Developers have to constantly switch between C# code and visual XML editors.
• Testing Complexity: Testing requires loading external files and evaluating string-based inputs.

The EasyDecisions Solution

EasyDecisions brings the power of decision tables directly into your C# codebase.

Instead of writing XML, you write this:

public class EligibilityDecision : Decision<MyInput, MyOutput>
{
    public EligibilityDecision() : base("Eligibility")
    {
        When(i => i.Age >= 18 && i.Country == "US")
            .Then()
            .Set(o => o.CanDrink = true)
            .Set(o => o.CanVote = true);
    }
}

By keeping your rules in code, you gain IntelliSense, compile-time validation, and seamless refactoring, while still keeping your business rules clean and readable.

When to use EasyDecisions?

You should consider using EasyDecisions when:

• You have complex mapping logic based on multiple input factors.
• You need to build pricing engines, discount calculators, or risk assessments.
• You have "spaghetti code" consisting of massive switch statements or nested if/else blocks.
• You need to reuse the same decision in multiple places. By encapsulating a decision (where one input generates one output) into a dedicated class, you avoid duplicating complex conditions across your codebase or creating unnecessary boilerplate dependency classes.