Pagination plugin returns incorect number of pages

[flash-gordon]

Describe the bug

If you paginate over a filtered relation (say, users.active) then rel.total will return incorrect results since it calls dataset.unfiltered which discard all the filtering.

To Reproduce

user.active.pager.total returns the total number of users

Expected behavior

user.active.pager.total returns the number of active users

Your environment

• Affects my production application: NO (or maybe? 😅)

[solnic]

@flash-gordon it calls unlimited, not unfiltered

[flash-gordon]

@solnic 🤦‍♂ ok
I'm still getting invalid results from .pager.dataset.unlimited.count, Sequel issues queries for the default dataset which is not expected. I'll take a deeper look

[solnic]

@flash-gordon oh wow that is puzzling

[flash-gordon]

Got it,

rom-sql/lib/rom/sql/plugin/pagination.rb

Lines 115 to 121 in bde6843

	klass.class_eval do
	defines :per_page
	option :pager, default: -> {
	Pager.new(dataset, per_page: self.class.per_page)
	}
	end

It happens because pager is eagerly evaluated and passed around with options when you chain relation calls. It means it always sticks to the default dataset. This is 💯 a bug, we should use memoization instead

[katafrakt]

So, I just was bitten by this. And I discovered a funny thing, maybe it'd help someone:

relation.where { ... }.per_page(per_page).page(page) # this works correctly
relation.per_page(per_page).page(page).where { ... } # this does not

Anyway, I thought I could try to fix it and make a PR, but it seems that tests are currently not passing on master, so I'm not sure how to proceed.

[solnic]

@katafrakt please target release-3.5 branch and then I could cherry-pick your fix into master