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Event subscribers allow you to react to events in your Medusa application, such as order creation, product updates, or custom events from your workflows. They enable asynchronous, decoupled event-driven architectures.

​
What is an Event Subscriber?

An event subscriber:
  • Listens to one or more events from the event bus
  • Executes asynchronously when events are triggered
  • Has access to the dependency injection container
  • Can trigger workflows, send notifications, or perform side effects
  • Exports a configuration specifying which events to listen to

​
Creating a Basic Subscriber

1

Create the Subscriber File

Create a file in src/subscribers/ with a default export function and configuration:
src/subscribers/brand-created.ts
import { SubscriberArgs, SubscriberConfig } from "@medusajs/framework"

export default async function brandCreatedHandler({
  event,
  container,
}: SubscriberArgs<{ id: string }>) {
  const logger = container.resolve("logger")

  logger.info(`Brand created with ID: ${event.data.id}`)
}

export const config: SubscriberConfig = {
  event: "brand.created",
}
2

Access Services and Modules

Resolve dependencies from the container:
import { Modules } from "@medusajs/framework/utils"
import { INotificationModuleService } from "@medusajs/framework/types"

export default async function brandCreatedHandler({
  event,
  container,
}: SubscriberArgs<{ id: string }>) {
  const notificationService = container.resolve<INotificationModuleService>(
    Modules.NOTIFICATION
  )

  await notificationService.createNotifications({
    to: "[email protected]",
    channel: "email",
    template: "brand-created",
    data: {
      brand_id: event.data.id,
    },
  })
}

export const config: SubscriberConfig = {
  event: "brand.created",
}
3

Execute Workflows

Trigger workflows in response to events:
import { Modules } from "@medusajs/framework/utils"
import { IWorkflowEngineService } from "@medusajs/framework/types"

export default async function orderCreatedHandler({
  event,
  container,
}: SubscriberArgs<{ id: string }>) {
  const workflowEngine = container.resolve<IWorkflowEngineService>(
    Modules.WORKFLOW_ENGINE
  )

  await workflowEngine.run("send-order-confirmation", {
    input: {
      order_id: event.data.id,
    },
  })
}

export const config: SubscriberConfig = {
  event: "order.created",
}

​
Subscriber Configuration

​
Single Event

export const config: SubscriberConfig = {
  event: "brand.created",
}

​
Multiple Events

export const config: SubscriberConfig = {
  event: ["brand.created", "brand.updated", "brand.deleted"],
}

​
With Context

Add metadata to identify the subscriber: 
export const config: SubscriberConfig = {
  event: "order.created",
  context: {
    subscriberId: "order-notification-handler",
  },
}

​
Real-World Examples

​
Payment Webhook Handler

This example shows processing payment webhooks and triggering workflows:
src/subscribers/payment-webhook.ts
import { processPaymentWorkflowId } from "@medusajs/core-flows"
import {
  IPaymentModuleService,
  ProviderWebhookPayload,
} from "@medusajs/framework/types"
import {
  Modules,
  PaymentActions,
  PaymentWebhookEvents,
} from "@medusajs/framework/utils"
import { SubscriberArgs, SubscriberConfig } from "@medusajs/framework"

export default async function paymentWebhookHandler({
  event,
  container,
}: SubscriberArgs<ProviderWebhookPayload>) {
  const paymentService = container.resolve<IPaymentModuleService>(
    Modules.PAYMENT
  )

  const processedEvent = await paymentService.getWebhookActionAndData(
    event.data
  )

  if (!processedEvent.data) {
    return
  }

  // Skip unsupported actions
  if (
    processedEvent?.action === PaymentActions.NOT_SUPPORTED ||
    processedEvent?.action === PaymentActions.CANCELED ||
    processedEvent?.action === PaymentActions.FAILED
  ) {
    return
  }

  const workflowEngine = container.resolve(Modules.WORKFLOW_ENGINE)
  await workflowEngine.run(processPaymentWorkflowId, {
    input: processedEvent,
  })
}

export const config: SubscriberConfig = {
  event: PaymentWebhookEvents.WebhookReceived,
  context: {
    subscriberId: "payment-webhook-handler",
  },
}

​
Send Notifications

Send notifications based on configurable events:
src/subscribers/order-notifications.ts
import { INotificationModuleService } from "@medusajs/framework/types"
import {
  ContainerRegistrationKeys,
  Modules,
  pickValueFromObject,
} from "@medusajs/framework/utils"
import { SubscriberArgs, SubscriberConfig } from "@medusajs/framework"

type NotificationConfig = {
  event: string
  template: string
  channel: string
  to: string
  resource_id: string
  data: Record<string, string>
}

const handlerConfig: NotificationConfig[] = [
  {
    event: "order.created",
    template: "order-created-template",
    channel: "email",
    to: "order.email",
    resource_id: "order.id",
    data: {
      order_id: "order.id",
    },
  },
]

const configAsMap = handlerConfig.reduce(
  (acc: Record<string, NotificationConfig[]>, h) => {
    if (!acc[h.event]) {
      acc[h.event] = []
    }
    acc[h.event].push(h)
    return acc
  },
  {}
)

export default async function orderNotifications({
  event,
  container,
}: SubscriberArgs<any>) {
  const logger = container.resolve(ContainerRegistrationKeys.LOGGER)
  const notificationService = container.resolve<INotificationModuleService>(
    Modules.NOTIFICATION
  )

  const handlers = configAsMap[event.name] ?? []
  const payload = event.data

  for (const handler of handlers) {
    try {
      await notificationService.createNotifications({
        template: handler.template,
        channel: handler.channel,
        to: pickValueFromObject(handler.to, payload),
        trigger_type: handler.event,
        resource_id: pickValueFromObject(handler.resource_id, payload),
        data: Object.entries(handler.data).reduce((acc, [key, value]) => {
          acc[key] = pickValueFromObject(value, payload)
          return acc
        }, {}),
      })
    } catch (err) {
      logger.error(`Failed to send notification for ${event.name}`, err.message)
    }
  }
}

export const config: SubscriberConfig = {
  event: handlerConfig.map((h) => h.event),
  context: {
    subscriberId: "order-notifications-handler",
  },
}

​
Sync Data to External System

src/subscribers/brand-sync.ts
import { BRAND_MODULE } from "../modules/brand"
import { IBrandModuleService } from "../modules/brand/types"
import { SubscriberArgs, SubscriberConfig } from "@medusajs/framework"
import { ContainerRegistrationKeys } from "@medusajs/framework/utils"

export default async function syncBrandToExternal({
  event,
  container,
}: SubscriberArgs<{ id: string }>) {
  const logger = container.resolve(ContainerRegistrationKeys.LOGGER)
  const brandService = container.resolve<IBrandModuleService>(BRAND_MODULE)

  try {
    const brand = await brandService.retrieveBrand(event.data.id)

    // Sync to external system
    await fetch("https://external-api.com/brands", {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify(brand),
    })

    logger.info(`Synced brand ${brand.id} to external system`)
  } catch (error) {
    logger.error(`Failed to sync brand ${event.data.id}`, error)
  }
}

export const config: SubscriberConfig = {
  event: ["brand.created", "brand.updated"],
  context: {
    subscriberId: "brand-external-sync",
  },
}

​
Event Data Types

Type your event data for type safety: 
interface BrandCreatedEventData {
  id: string
  name: string
}

export default async function brandCreatedHandler({
  event,
  container,
}: SubscriberArgs<BrandCreatedEventData>) {
  // event.data is now typed
  const brandId = event.data.id
  const brandName = event.data.name
}

​
Built-in Events

Medusa emits events for core entities:
  • order.created, order.updated, order.canceled
  • product.created, product.updated, product.deleted
  • customer.created, customer.updated
  • payment.created, payment.captured
  • fulfillment.created, fulfillment.shipped
And many more. See the Events concept for more information about the event system.

​
Custom Events from Workflows

Emit custom events using workflow hooks:
src/workflows/brand/create-brand.ts
import { createHook, createWorkflow } from "@medusajs/framework/workflows-sdk"

export const createBrandWorkflow = createWorkflow(
  "create-brand",
  (input) => {
    const brand = createBrandStep(input)

    const brandCreated = createHook("brandCreated", {
      id: brand.id,
      name: brand.name,
    })

    return new WorkflowResponse(brand, {
      hooks: [brandCreated],
    })
  }
)
Subscribe to the hook:
src/subscribers/brand-created.ts
export const config: SubscriberConfig = {
  event: "brandCreated",
}

​
Error Handling

Handle errors gracefully to prevent subscriber failures from affecting the main flow: 
export default async function brandHandler({
  event,
  container,
}: SubscriberArgs<{ id: string }>) {
  const logger = container.resolve("logger")

  try {
    // Your logic here
  } catch (error) {
    logger.error(
      `Failed to process brand event for ${event.data.id}`,
      error.message
    )
    // Don't throw - let the subscriber complete
  }
}

​
Best Practices

  • Keep subscribers focused on a single responsibility
  • Use workflows for complex business logic instead of putting it in subscribers
  • Handle errors gracefully - don’t let subscriber failures break the main flow
  • Use typed event data for type safety
  • Add context with subscriberId for easier debugging
  • Use the logger for debugging and error tracking
  • Consider idempotency when handling events (events may be delivered multiple times)
  • Don’t perform long-running operations synchronously - use workflows or background jobs

​
Next Steps

Create Workflows

Build workflows triggered by subscribers

Scheduled Jobs

Create time-based background tasks

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