Hi Ben,

It involves a couple of things. Firstly on Shopify you need to come out with a standardized tagging system for all your products (the car parts). The purpose is to tag your products with the correct car-specific tagging. For example, a set of 19″ Wheels can be tagged with bolt patterns of all the cars that can be fitted with this wheels. Other common traits are such as chassis number, body type, engine code and transmission.

Once this is done, you need to use an app like Metafields Solid to define a custom field for you Collections to map between the traits and Collections. The Wheels collection for example, the trait that matters is probably the bolt pattern.

Then comes the technical and coding part as described in this blog post. The client entered the “vehicle and traits mapping” data into Google Spreadsheet like you see in this simplified screenshot http://i1.wp.com/www.stampede-design.com/blog/wp-content/uploads/2014/05/Screenshot_on_5.2.2014_at_4.13.06_PM.png and I converted them into a TaffyDB data file that looks a little bit like a JSON file. Using JavaScript and TaffyDB, I coded the logic for the cascading dropdowns. And finally with the help of Shopify’s Liquid template tags I coded the logic where after a particular vehicle is selected from the dropdowns, the website refreshes and only shows parts relevant to the selected vehicle.

Here’s the live implementation http://www.fastwrx.com/collections/wheels