Does Pagy::Keyset support AR relations ordered with SQL string expressions?

[thomascchen]

Consider the following example:

relation = User.order("LOWER(users.name) ASC").order(:id)
keyset = Pagy::Keyset.new(relation)

This raises the following error:

(irb):54:in `<main>': undefined method `value' for an instance of String (NoMethodError)

          keyset[node.value.name.to_sym] = node.direction

[ddnexus]

Not out of the box ATM

A simple (for us) way of doing it, would require a new feature that we should be able to add easily, and your custom query, run inside an :after_latest lambda.

Another way would be supporting it natively, but it would probably complicate the code quite a bit.

[ddnexus]

Hey, I just noticed the actual content of your order string, and I'm not sure you can even have an index including it, which would be a disaster for performance.

In your particular case the solution would be adding a lower_name (column populated with the actual lower name) and using it for the index and with .order(:lower_name), which - of course - is already covered by pagy.

[thomascchen]

Thanks @ddnexus. I made up the example, but you are correct and that makes a lot of sense. In my real world case, I have many possible columns that could be combined in many different combinations for my order, and I don't have composite indexes set up for all of them. I also don't have a huge dataset, so keyset is probably not the right tool for my case, but it looked awesome, so I wanted to try it. 😀 The countless extra is likely a better fit for my case. Thank you for your response and for your work on this gem!