A appreciate that this is not ideal but I have a dataLayer ecommerce tracking output which is in the old format for GA and is not compatible with Google Tag Manager. However, all of the values are there.

Is there a way you set up eccomerce tracking dataLayer in GTM and then use variables to pull in the values you need?


I believe you can do this, but it will be complicated enough that, if at all possible, you may prefer to make the switch to the current Enhanced Ecommerce dataLayer syntax.

In Google Tag Manager, the important thing to know is that you can read EEc data from a variable instead of from the dataLayer. You have to enable overriding settings in the tag and then open "More Settings" and "Enhanced Ecommerce" to find the option.

Screenshot of settings to read EEc data from variable in GTM

You'll define the variable standing in for the dataLayer as a GTM Custom JavaScript variable that returns the object you would be pushing into the dataLayer if you were using the modern syntax.

There is one potential complication, though. The modern dataLayer syntax, besides being natively supported, is very nested. When you click a product, the "products" array is accessible as ecommerce.click.products in the dataLayer. If you are using the _gaq function (which seemed most likely to me since it pushes an array of its arguments into the dataLayer), that's not true.

Let's do a rough translation of product click events from _gaq to the current dataLayer, as an example. The _gaq syntax translates to

        "content_type": "product",
        "items": [
                "id": "P12345",
                "name": "Android Warhol T-Shirt",
                "list": "Search Results",
                "brand": "Google",
                "category": "Apparel/T-Shirts",
                "variant": "Black",
                "list_position": 1,
                "quantity": 2,
                "price": 2

If you tried to access "items" without somehow specifying the "select_content" entry I would worry it might grab items out of, say, an earlier product impressions dataLayer push. My (untested) JS to get the correct entry in the _gaq dataLayer is as follows:

function() {

// find the select_content entry

var clickArr = dataLayer.filter( function(entry) { 
               return (entry[1] === 'select_content'); });

// clickArr is an array containing the array we wanted,
// in which the object containing "items" is the index-2 entry

var item = clickArr[0][2].items[0];

// item is the object containing product data

return {
    'event': 'productClick',
    'ecommerce': {
        'click': {
            'actionField': {'list': item.list},
            'products': [{
                'name': item.name,
                'id': item.id,
                'price': item.price,
                'brand': item.brand,
                'category': item.category,
                'variant': item.variant,
                'position': item.position


I left the "event": "productClick" part in there, since it is in the usual dataLayer push, but my expectation is it doesn't matter whether it's there or not.

To build a product impressions object you'd have to iterate through the objects in the original "items" array; if there are also promotion impressions and clicks, it would be prudent to edit the dataLayer filter to also make sure you're getting the "content_type": "product" entry.


I don't know about eccommerce tracking. But the answer to the question in the title is yes. You can change dataLayer variable name in GTM. Add a l parameter do the script src url to specify variable name for the data layer. See this example where it is set to foo:

<!-- Global site tag (gtag.js) - Google Analytics -->
<script async src="https://www.googletagmanager.com/gtag/js?id=UA-123456789-1&l=foo"></script>
  window.foo = window.foo || [];
  function gtag(){foo.push(arguments);}
  gtag('js', new Date());

  gtag('config', 'UA-123456789-1');

Credits to Eike Pierstorff at StackOverflow.

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