Flow Integration
Overview
R+ Back in Stock Flow Integration lets you build automated workflows triggered by back-in-stock subscription activity in your Shopify store. These workflows are created inside Shopify Flow and rely on two core building blocks: Triggers and Actions.
Triggers are the events that kick off a workflow — in this case, actions customers or guests take within the R+ Back in Stock app.
Actions are the tasks that get executed once the trigger fires. A common starting point is the Log output action, which records workflow activity for debugging and monitoring purposes.
R+ Back in Stock supplies the triggers whenever customers subscribe or unsubscribe from product restock alerts. Unsubscribe events typically fire automatically after a restock notification is sent — once a customer has been notified, their subscription is removed.
Shopify Flow's visual designer lets you define all the logic and follow-on steps. For a broader introduction to Shopify Flow, visit the Shopify Flow overview page.
Supported Triggers
The R+ Back in Stock integration currently supports four triggers:
Customer subscribed to a product — fires when a logged-in customer subscribes to receive a back-in-stock notification for a specific product variant.
Customer unsubscribed from a product — fires when a logged-in customer removes their back-in-stock subscription for a product variant. This also fires automatically after a restock notification email is sent.
Guest subscribed to a product — fires when a non-logged-in visitor subscribes to receive a restock alert for a product variant.
Guest unsubscribed from a product — fires when a non-logged-in visitor removes their restock subscription for a product variant. This also fires automatically after a restock notification email is sent.
To explore other apps you can connect to within your workflows, check out the full list of supported Shopify Flow connectors.
Trigger Data
Each trigger passes data into the workflow automatically. Here is what each one provides:
Customer subscribed / Customer unsubscribed
These triggers include the subscriber's email address, the product ID, the product variant ID, and the customer ID. All four fields are available as variables you can reference in downstream actions.
Guest subscribed / Guest unsubscribed
These triggers include the subscriber's email address, the product ID, and the product variant ID. Because guests are not logged in, no customer ID is available.
How It Works
Whenever a customer or guest performs one of the supported subscription actions, R+ Back in Stock sends an event to Shopify Flow along with all the relevant data about that action. From there, your configured workflow takes over and automatically carries out whatever steps you've defined.
Once you publish a workflow, it runs in the background without any manual intervention. Every qualifying subscription action after that point will trigger it automatically. You can find Shopify's step-by-step guidance on building workflows in their create a workflow help doc.
Setup Instructions: Trigger → Log Output
Follow these steps to build a basic workflow that logs every subscription event — a great starting point for testing your integration before adding more complex actions.
1. Install Shopify Flow
If you haven't already, install the Shopify Flow app from the Shopify App Store.
2. Create a new workflow
Open Shopify Flow and click the Create workflow button.
3. Select your trigger
In the visual workflow builder, click Select a trigger and choose R+ Back in Stock from the list of available apps.
4. Choose a subscription event
Pick the specific trigger you want to act on — for example, Customer subscribed to a product.
5. Add a Log output action
Click Then to add an action, then search for and select Log output. This action writes the trigger data to Flow's run log, which you can review at any time inside Shopify Flow. In the Log output configuration, you can reference any of the trigger variables — for instance, the subscriber's email or the variant ID — to make log entries more informative.
6. Save and activate the workflow
Once everything is configured, click Turn on workflow. It will go live on your store immediately and begin capturing subscription events.
Reviewing Log Output
After activating the workflow, you can verify it is working correctly by checking the run history inside Shopify Flow. Navigate to your workflow, open the Run log tab, and you will see an entry for each subscription event along with the data that was passed through. This is particularly useful for confirming that the correct email addresses and variant IDs are being captured before you build more advanced actions on top of the trigger.
What to Build Next
Once you have confirmed the integration is working with Log output, you can replace or extend it with more powerful actions. Common examples include sending an internal email notification to your team, adding the subscriber to a customer segment, tagging the customer in Shopify, or triggering a flow in a connected marketing platform.
The trigger data — email, product ID, variant ID, and customer ID — is available as variables in all downstream actions.
Do you need help?
If you have any questions or run into issues, please contact us — we’re happy to help.