I have two product types "standard" and "addon" these are just a custom field flag. An "addon" product can only be purchased if a "standard" product in in the cart.

How would I go about coding this up? Ideally it'd be great to have a conditional that I can run to disable the add to cart button for addon products till a standard product has been added to the cart. Soon as one standard product has been added to the cart any number of addons may be added.

I have seen this question but it's not the same. In this case it has to be a specific type of product not just any product.



  • I would create a custom EE or Cartthrob plugin that returns a true|false value depending on whether the specified product is in the cart, and enable|disable the button via this. Jun 20, 2014 at 1:31
  • Thanks for the suggestion Bradley, unfortunately I wouldn't know where to start.
    – Andy Homan
    Jun 22, 2014 at 13:30

1 Answer 1


I am going to assume (hopefully correctly) you are working with logged in users at the time of purchase, so that there is a way to check if the member in question has previously purchased a standard product.

You could do this several ways I think, but here’s what jumped into my head using the regular channel entries tag and not the query tag or something more complex.

If you did a search on the Purchased Items (not orders) channel using the logged in user’s ID and search:url_title="name-of-standard-product" it should return all of the purchases for that user, who had already purchased a standard product, to run a comparison against.

So if the page URI that contained your standard and addon products ended with "my-product-name" and you placed the above concept into a LowVariable for example (snippets, etc. could work too), I think it would look like this.


  status="not Closed" 

In your template with the add to cart tags:

{if '{exp:low_variables:parse var="variable-name" preparse:user_id="{logged_in_user_id}" preparse:url_segment="{url_title}"}'=='true'}
**show the add to cart for addons**
**You must purchase the standard product first**

You could do this with javascript too of course to disable the Add to Cart buttons, but hopefully this gets you started.

  • Hi Derrick. Thanks for the feedback. Sorry No, the customer will NOT be logged in. I've actually just realised (it was late last night when I posted this) that the standard project only needs to be in the cart NOT purchased. Sorry for any confusion. I'll edit the question now to reflect this.
    – Andy Homan
    Jun 20, 2014 at 0:38

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