A user is attempting to use Shopify Flow to automatically add +1 to variant inventory when an order is triggered, but the workflow isn’t functioning despite showing successful completion.
Core Issue:
The user configured a flow using “Product variant quantity changed” trigger with the expression {{productVariant.inventoryQuantity | plus: 1}}
They’re trying to update inventory via metafield namespace/key, which is incorrect
No actual inventory changes occur despite the flow completing successfully
Expert Response:
The metafield approach won’t work—it’s custom data, not actual inventory
No native “Update inventory” action exists in Shopify Flow
The current setup would create an infinite loop (each inventory update triggers another update)
Solution: Use the “Order created” trigger instead, then implement the “Send HTTP Request” action to call Shopify’s inventory API directly
This API approach is noted as fairly advanced for users unfamiliar with API calls
Status: The discussion provides a technical workaround but requires API knowledge to implement properly.
Summarized with AI on November 14.
AI used: claude-sonnet-4-5-20250929.
Hey y’all, I stuck on Shopify flow since hours to do something really easy :
I want to add +1 quantity to my variant inventory when an order is triggered (Product variant quantity changed)
SO basically on the screenshot it’s just
{{productVariant.inventoryQuantity | plus: 1}} when (Product variant quantity changed) but I think I’m messing with my Metafield namespace and Key, and I can’t figure it out…
All my actions triggered are completed successfully but NOTHING happens on my inventory, totally stay the same.
Even tho I actualised many times the variant inventory of many products
That metafield is a custom data field and not the inventory for your variant. You cannot use that to set the inventory. There isn’t current an “Update inventory” action. In fact, the way you set this up would result in an infinite loop where for every inventory update, it would update the inventory +1.
Since you want this to run on Order created, use the Order created trigger. If you want to adjust the inventory, you can accomplish that by using Send HTTP Request to call the API for changing inventory. This is pretty advanced though, if you are not familiar with making API calls.
