Decorators

`@OnEvent(type, retry?)`

Registers a method as a standalone event handler. The method is discovered at module init and attached to the Synkro instance via synkro.on().

import { Injectable } from "@nestjs/common";
import { OnEvent } from "@synkro/nestjs";

@Injectable()
export class NotificationHandler {
  @OnEvent("user.signup", { maxRetries: 3, retryDelay: 1000 })
  async handleSignup(payload: { email: string }) {
    await sendWelcomeEmail(payload.email);
  }

  @OnEvent("order.completed")
  async handleOrderCompleted(payload: { orderId: string }) {
    await sendOrderConfirmation(payload.orderId);
  }
}

Parameters

Parameter	Type	Description
`type`	`string`	The event type to listen for.
`retry`	`RetryConfig`	Optional retry configuration (`maxRetries`, `retryDelay`).

`@OnWorkflowStep(workflow, step)`

Binds a method as the handler for a specific step in a workflow. This replaces inline handler functions in the workflow definition.

import { Injectable } from "@nestjs/common";
import { OnWorkflowStep } from "@synkro/nestjs";

@Injectable()
export class OrderWorkflowHandler {
  @OnWorkflowStep("order-fulfillment", "validate-inventory")
  async validateInventory(payload: { items: string[] }) {
    // check stock levels
    return { available: true };
  }

  @OnWorkflowStep("order-fulfillment", "charge-payment")
  async chargePayment(payload: { orderId: string; amount: number }) {
    // process payment
    return { transactionId: "txn_123" };
  }

  @OnWorkflowStep("order-fulfillment", "ship-order")
  async shipOrder(payload: { orderId: string }) {
    // create shipping label
    return { trackingNumber: "TRACK_456" };
  }
}

Parameters

Parameter	Type	Description
`workflow`	`string`	The `name` of the workflow this step belongs to.
`step`	`string`	The `type` of the step within that workflow.

Workflow definition with decorators

When using @OnWorkflowStep, define your workflow steps without inline handler functions. The module will patch in the decorated methods at startup.

import type { NestSynkroWorkflow } from "@synkro/nestjs";

export const orderFulfillmentWorkflow: NestSynkroWorkflow = {
  name: "order-fulfillment",
  triggerEvent: "order.created",
  steps: [
    {
      type: "validate-inventory",
      onSuccess: "charge-payment",
      onFailure: "notify-out-of-stock",
    },
    {
      type: "charge-payment",
      onSuccess: "ship-order",
      onFailure: "refund-payment",
    },
    {
      type: "ship-order",
      retry: { maxRetries: 3, retryDelay: 2000 },
    },
  ],
};

The NestSynkroWorkflow type is identical to the core SynkroWorkflow type except that handler is optional on each step — allowing handlers to be provided via decorators instead.