@walkeros/transformer-router

Router transformer for walkerOS — dynamic chain branching based on ingest metadata.

Installation

npm install @walkeros/transformer-router

Usage

import { transformerRouter } from '@walkeros/transformer-router';

const flow = await startFlow({
  transformers: {
    router: {
      code: transformerRouter,
      config: {
        settings: {
          routes: [
            {
              match: { key: 'path', operator: 'prefix', value: '/gtag' },
              next: 'gtag-parser',
            },
            {
              match: { key: 'path', operator: 'prefix', value: '/webhooks' },
              next: 'webhook-parser',
            },
            { match: '*', next: ['validator'] },
          ],
        },
      },
    },
  },
  sources: {
    express: { code: sourceExpress, next: 'router' },
  },
});

How It Works

The router inspects context.ingest (set by the source) and evaluates route rules in order. The first matching route branches the transformer chain to a different sub-chain. Non-matching events pass through unchanged.

Routes are compiled to closures at init time for fast runtime evaluation.

Route Configuration

interface Route {
  match: MatchExpression | '*'; // Condition or wildcard
  next: string | string[]; // Target transformer chain
}

Match Operators

| Operator | Description | | ---------- | ---------------------- | | eq | Exact string match | | prefix | Starts with | | suffix | Ends with | | contains | Substring match | | regex | Regular expression | | gt | Greater than (numeric) | | lt | Less than (numeric) | | exists | Key is present |

All conditions support not: true for negation.

Logical Combinators

Combine conditions with and/or, nestable to any depth:

{
  match: {
    and: [
      { key: 'path', operator: 'prefix', value: '/api' },
      { key: 'method', operator: 'eq', value: 'POST' },
    ],
  },
  next: 'api-parser',
}