Getting started

Install

pnpm add @cqrs-ddd/pipeline

The packages require Node.js 22.12 or later, or another runtime with AsyncLocalStorage (Bun, Deno). They are published as ES modules; a CommonJS application loads them with require().

Create a pipeline

A pipeline holds the behavior instances and the behaviors that apply to every operation. Create it once, in a module of its own:

pipeline.ts

import { createPipeline, LoggingBehavior, logging } from '@cqrs-ddd/pipeline';

export const pipeline = createPipeline({
  behaviors: [new LoggingBehavior(console)],
  globalBehaviors: { before: [logging({ requestResponseLogLevel: 'log' })] },
});

behaviors are the instances, one per behavior class; a behavior placed without an instance is constructed with no arguments. globalBehaviors places behaviors around every wrapped operation.

Wrap a function

pipeline.wrap(options, ...entries) returns a wrapper. Applied to a function, it returns a new async function that runs the behaviors around it:

import { pipeline } from './pipeline.js';

export const getPrice = pipeline.wrap({ name: 'getPrice', kind: 'query' })(
  async (sku: string) => prices.find(sku),
);

await getPrice('apple');

A plain function needs a name, which keys and logs use to tell operations apart, and a kind: a query reads, a command changes state, an event reacts. Behaviors use the kind to decide what applies; idempotency, for example, applies to commands.

Decorate a method

The same wrapper decorates a method, with TypeScript’s standard decorators or with experimentalDecorators:

class Prices {
  @pipeline.wrap({ kind: 'query' })
  async find(sku: string) {
    return this.store.get(sku);
  }
}

A method is named Class.method (here Prices.find) unless the options name it.

Add a behavior

Each concern is a package. Install it, give the pipeline an instance, and add its entry where it applies:

pnpm add @cqrs-ddd/pipeline-zod zod

import { validated } from '@cqrs-ddd/pipeline-zod';
import { z } from 'zod';

export const placeOrder = pipeline.wrap(
  { name: 'placeOrder', kind: 'command' },
  validated(z.object({ sku: z.string(), qty: z.coerce.number().int().positive() })),
)(async (order) => orders.place(order));

Next

• How an operation is wrapped: names, kinds and requests.
• The plain Node.js guide: a complete, tested example.
• Packages: every behavior and its options.
• CQRS without NestJS: an application of commands, queries and events on @cqrs-ddd/cqrs, wired with createCqrs().
• NestJS & @cqrs-ddd: integrating with NestJS using @cqrs-ddd/nestjs.
• The repository’s applications: small applications that each use one package family (the pipeline alone, the domain alone, the repositories alone), and api/, which uses them all.