---
title: "Trigger Shopify Flow on customer metafield updates"
description: "Automatically tag products matching a customer's clothing size when they update their profile. Uses Workflow Trigger Extensions' customer metafield trigger."
canonical: "https://docs.workflow-trigger-extensions.app/customer-metafield-update-guide"
---

# Trigger Shopify Flow on customer metafield updates

We will assume the following scenario to understand how we can use the **Customer Metafield Update** trigger from the **Workflow Trigger Extensions** app to tag products based on a customer's clothing size preference.

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## Scenario: Customer updates their size → All matching products are automatically tagged

A fashion retailer lets customers save their preferred clothing size in their profile. Every time a customer updates their size, Flow automatically finds all products available in that size and tags them, making it easy to build size-based collections, filters, and personalized recommendations.

The metafield `custom.clothing_size` on a customer record is updated to a new size value (e.g. `"XL"`).

A condition checks that the metafield value is not blank, ensuring the workflow only runs when a valid size has been set.

Flow queries all products that have a variant option matching the customer's size value (e.g. `"XL"`).

Each matched product is tagged with `available-in-XL` (or whatever size was set), making them easy to surface in size-specific collections and storefronts.

An email is sent to the customer letting them know new products in their size are available to shop.

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## How to build this flow

You can build this flow by following these 2 steps:
1. Add the Customer Metafield Trigger in the app
2. Create the Shopify Flow

You can also see these steps in the demo video below (video has no voice):

[Video](https://www.youtube.com/watch?v=4kQzRshJdpo)

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### 1) Add trigger to Customer Metafield

First you need to register the trigger on the customer metafield you want to monitor.
- First make sure you have the Customer Access from the Workflow Trigger Extensions → Dashboard → Setup Guide you will see the Grant Customer access, you can also see the permissions from the Workflow Trigger Extensions → Permissions
- Then you have to create the Customer metafield trigger. If you do not see the Setup Guide, navigate directly to the app's metafield triggers page.
- Press the **Add Trigger** button to create a new trigger.
- Select the resource type **Customer** and search for the metafield `custom.clothing_size`. Select it and press the **Add Trigger** button to confirm.

If you are not able to see your metafield in the selected resourse even if you have the metafield present. Press **Refresh Metafields** button in Metafield Triggers page, it will clear the cache and you will be able to see your metafield.

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### 2) Create the Shopify Flow

Now create the Flow that finds matching products and tags them whenever the customer's size is updated.
- Open Shopify Flow and create a blank workflow. Select the** Metafield Update** trigger from the **Workflow Trigger Extensions** app.
- Click **Record Event**, then in a new tab update a customer's `custom.clothing_size` metafield to `"XL"` to capture a sample payload. Click **Select Test Event** to load the recorded payload into the workflow builder.
- You will see the payload containing the customer data and the new metafield value. This holds the new size value the customer just set (e.g. `"XL"`).
- Add a **Condition** to check that the metafield value is not blank AND `metafield.key = "clothing_size"` AND `resourceType = "CUSTOMER"`
- Add an **Action: Get product variant data** and filter by variant option1 matching the metafield value: `Variant option1 == {{ metafield.value }}` This retrieves all products that have a variant in the customer's size.

In my case, I have only one option available for the variant (size) and its option1. If you have variant option at any other location then it will be option2 or maybe option3.
- Add an **Action: Add tag to product** for each product returned: `available-in-{{ metafield.value }}` For a customer who set size `"XL"`, this adds the tag `available-in-XL` to every matching product.
- Optionally, add an **Action: Add tag to customer** to keep the customer record in sync: `size-{{ metafield.value }}`