Context

Context is a powerful feature that allows rules to share state and communicate with each other during rule execution. Each session has its own isolated context that persists throughout the rule execution process.

Basic Usage

Context can be defined in two ways:

1. Using key-value pairs:

const engine = new Engine().context("count", 0).context("message", "");

2. Using an object:

const engine = new Engine().context({
  count: 0,
  message: "",
  metadata: {
    timestamp: new Date(),
    version: "1.0",
  },
});

Type Safety

Context is fully type-safe. The types are inferred from your context definitions:

const engine = new Engine()
  .context({
    count: 0,
    message: "",
    items: [] as string[],
  })
  .rule("example", (facts, { context }) => {






    
    context.count++;
    context.message = "Hello";
    context.items.push("item");
  });

Context Functions

If you want to create reusabled functions that can interact with context, see helpers

Context Inheritance

When combining engines, context is merged:

const baseEngine = new Engine().context({ base: "value" });

const extendedEngine = new Engine()
  .context({ extended: "value" })
  .use(baseEngine);

// The context now has both 'base' and 'extended' properties

const session = extendedEngine.createSession();

session.context.base;
session.context.extended;

Best Practices

• Initialize All Properties: Always initialize all context properties you plan to use
• Use Type Assertions: When working with arrays or complex types, use type assertions for better type inference