I had some fun with this one. Implementing pagination almost always gives me a touch of anxiety, especially your typical LIMIT/OFFSET pagination. I had recently discovered the more performant cursor pagination from this post and wanted to give it a go. I created a service in my latest Roda app to be able to take some arguments, chain a query and run the high-performance pagination from there.
I started with implementing a couple different gems, then was able to gather what I needed to create my own version with more control. Parulian's post and repo was a huge inspiration for my service (big thanks!). I needed the returned formatting to be a little more specific and the query chaining capabilities to be a bit more explicit, so I was able to create a base structure around his library and convert the service based on my needs.
Here's a little explanation of the code. We basically have a parent service class (not shown) that converts args passed into an instance into accessors. We use a class method to define defaults, and another to pass in keyword arguments (limited to the accessors listed) to define the boundaries of the query.
PaginationService.paginate defaults to a descending-order page showing the last 25 reviews that were created. The previous and next cursor are returned in the "navigation" pair in the final JSON. What I like about the implementation is that we can pass in an array to the where: option that represents a parameterized query to be chained to the final pagination (i.e. limiting reviews that have a rating higher than 5).
I'm totally nerding out over my own code, but maybe it can help someone that wants to set up their own cursor pagination. Happy trails, devs!