Need to create a new scope... can I combine it with an existing scope?

I have a scope I defined as published (which basically is used for products that are not in draft mode = ‘false’ and between the startdate and enddate’ of today’s date)

I want to add to that the difference (or qty remaining, a calculated SQL field) that is the difference between the Sum ( of product_in in carts) - Product.qty (then ordered that descending).

Is this possible?

Could you please add some example code?

You’re probably looking for #merge

Post.where(published: true).joins(:comments).merge( Comment.where(spam: false) )
# Performs a single join query with both where conditions.

recent_posts = Post.order('created_at DESC').first(5)
Post.where(published: true).merge(recent_posts)
# Returns the intersection of all published posts with the 5 most recently created posts.
# (This is just an example. You'd probably want to do this with a single query!)