src=”https://www.facebook.com/tr?id=2931116163786365&ev=PageView&noscript=1″

/>

• View Content Event:

Create Data Layer Variables (Name – Data Layer Variable Name) :

dlv – fb – product id : ecommerce.items.0.item_id

dlv – fb – product price : ecommerce.items.0.price

dlv – fb – product name : ecommerce.items.0.item_name

Trigger:

Event equals: view_item

• Add to cart Event

Create Data Layer Variables (Name – Data Layer Variable Name) :

dlv – fb – product id : ecommerce.items.0.item_id

dlv – fb – product price : ecommerce.items.0.price

dlv – fb – product name : ecommerce.items.0.item_name

Trigger:

Event equals: add_to_cart

1. Purchase Event:

Step – 01: Create Data layer variable for pushing Purchase value

Name – Data Layer Variable Name: dlv – FB – Purchase value
ecommerce.purchase.actionField.revenue
or 

ecommerce.value

Step – 02: Create Data Layer Variable for Products (Multiple items)

Name – Data Layer Variable Name: dlv – FB – Purchase Product  ecommerce.items 

Step – 03: Create Custom JavaScript Variable to push multiple products info from Array 

Name: jsv – FB – Purchase Product – AR

Code: 

function() {

 var items = {{dlv – FB – Purchase Product}};

 return items.map(function(items) { return items.item_id; }).join();

}

Step – 04: Create Trigger for purchase event

Event equals: purchase

Step -05: Create tag and finally test from preview mode

Code: 

Source: Combine GTM Product IDs for Facebook Conversion Tags on Magento | Elevar (getelevar.com)