Segment

1. Log in to your Segment account
2. Navigate to **Connections** > **Functions** in the left sidebar
3. Click **New Function** and select **Destination**
4. Name your function (e.g., Novu Destination) and click **Create Function**

The Destination Function will handle two key Segment event types:
- **identify**: Creates or updates a subscriber in Novu
- **track**: Triggers a notification workflow in Novu

Paste the following complete code into the Segment Function editor:

```jsx
/**
 * Handles identify events: Creates or updates a subscriber in Novu
 * @param {SegmentIdentifyEvent} event - The Segment identify event
 * @param {FunctionSettings} settings - Function settings including API key
 */
async function onIdentify(event, settings) {
  const endpoint = 'https://api.novu.co/v2/subscribers';
  const apiKey = settings.apiKey;

  if (!apiKey) throw new Error('Novu API key is missing in settings');
  if (!event.userId) throw new Error('userId is required in identify event');

  const subscriberData = {
    subscriberId: event.userId,
    firstName: event.traits?.firstName || null,
    lastName: event.traits?.lastName || null,
    email: event.traits?.email || null,
    phone: event.traits?.phone || null,
    avatar: event.traits?.avatar || null,
  };

  try {
    const response = await fetch(endpoint, {
      method: 'POST',
      headers: {
        'Authorization': `ApiKey ${apiKey}`,
        'Content-Type': 'application/json'
      },
      body: JSON.stringify(subscriberData)
    });

    const responseBody = await response.json();
    if (!response.ok) {
      if (response.status >= 500 || response.status === 429) {
        throw new RetryError(`Server error: ${response.status}`);
      }
      throw new Error(`API error: ${response.status} - ${responseBody.message || 'Unknown error'}`);
    }
  } catch (error) {
    throw error instanceof RetryError ? error : new RetryError(error.message);
  }
}

// Mapping of Segment track events to Novu workflows
const EVENT_TO_WORKFLOW_MAPPINGS = {
  'User Registered': 'welcome'
  // Add more mappings: 'Event Name': 'novu-workflow-name'
};

/**
 * Handles track events: Triggers a notification workflow in Novu
 * @param {SegmentTrackEvent} event - The Segment track event
 * @param {FunctionSettings} settings - Function settings including API key
 */
async function onTrack(event, settings) {
  const endpoint = 'https://api.novu.co/v1/events/trigger';
  const apiKey = settings.apiKey;

  if (!apiKey) throw new Error('Novu API key is missing in settings');
  if (!event.userId) throw new Error('userId is required in track event');

  const workflow = EVENT_TO_WORKFLOW_MAPPINGS[event.event];
  if (!workflow) throw new Error(`No workflow mapped for event: ${event.event}`);

  const triggerEvent = {
    name: workflow,
    to: { subscriberId: event.userId },
    payload: event.properties || {}
  };

  try {
    const response = await fetch(endpoint, {
      method: 'POST',
      headers: {
        'Authorization': `ApiKey ${apiKey}`,
        'Content-Type': 'application/json'
      },
      body: JSON.stringify(triggerEvent)
    });

    const responseBody = await response.json();
    if (!response.ok) {
      if (response.status >= 500 || response.status === 429) {
        throw new RetryError(`Server error: ${response.status}`);
      }
      throw new Error(`API error: ${response.status} - ${responseBody.message || 'Unknown error'}`);
    }
  } catch (error) {
    throw error instanceof RetryError ? error : new RetryError(error.message);
  }
}
```

<AccordionGroup>
  <Accordion title="Code Explanation">
    - **`onIdentify`**:
        - Maps Segment traits (e.g., firstName, lastName, email) to Novu subscriber fields
        - Uses Novu's `/v2/subscribers` endpoint
        - Creates or updates subscribers (Novu's API is idempotent for existing `subscriberIds`)
    - **`onTrack`**:
        - Maps Segment `track` events to Novu workflows using `EVENT_TO_WORKFLOW_MAPPINGS`
        - Sends the event properties as the payload to trigger a workflow via `/v1/events/trigger`
    - **Error Handling**: Retries on server errors (5xx) or rate limits (429), fails fast on other errors
  </Accordion>
</AccordionGroup>

<Tip>
  Update `EVENT_TO_WORKFLOW_MAPPINGS` with your Segment event names and corresponding Novu workflow names.
</Tip>

1. Click **Save** in the Function editor
2. Enable the function by toggling it to **Active**

1. Go to **Connections** > Select your **Source** (e.g., website, app)
2. In the **Destinations** tab, click **Add Destination**
3. Choose your **Novu Destination Function** from the list
4. Click **Connect**. When prompted, enter your **Novu API key** in the apiKey field
5. Save the configuration

Verify everything works:

<AccordionGroup>
  <Accordion title="1. Send an identify event">
    Example:
    ```json
    {
      "type": "identify",
      "traits": {
        "name": "Peter Gibbons",
        "email": "[email protected]",
        "plan": "premium",
        "logins": 5
      },
      "userId": "97980cfea0067"
    }
    ```
    Check Novu's **Subscribers** list to confirm the subscriber appears.
  </Accordion>

  <Accordion title="2. Send a track event">
    Example:
    ```json
    {
      "type": "track",
      "event": "User Registered",
      "properties": {
        "plan": "Pro Annual",
        "accountType" : "Facebook"
      }
    }
    ```
    Verify the `welcome` workflow triggers in Novu's activity feed.
  </Accordion>
</AccordionGroup>

Use Segment's **Debugger** to monitor function calls and catch any errors.