Order query by subquery. Eloquent vs MySql - mysql

Question

I would like to get lists which are followed by a particular user and order lists by created_at(by date when lists were followed). Not sure why it doesn't work (order by) using Eloquent:
$myQuery = PlaceList::query()
->where('private', 0)
->whereHas('followers', function ($query) use ($userID) {
$query->where('created_by_user_id', $userID);
})
->orderByDesc(
Follow::query()->select('created_at')
->where('created_by_user_id', $userID)
->where('followable_id', 'place_lists.id')
)
->get()
This is what I've got when I use dd($myQuery->toSql()):
select
*
from
`place_lists`
where
`private` = ?
and exists (
select
*
from
`follows`
where
`place_lists`.`id` = `follows`.`followable_id`
and `created_by_user_id` = ?
and `follows`.`deleted_at` is null
)
and `place_lists`.`deleted_at` is null
order by (
select
`created_at`
from
`follows`
where
`created_by_user_id` = ?
and `followable_id` = ?
and `follows`.`deleted_at` is null
) desc
But when I populate MySql with data it does work:
select
*
from
`place_lists`
where
`private` = 0
and exists (
select
*
from
`follows`
where
`place_lists`.`id` = `follows`.`followable_id`
and `created_by_user_id` = 13
and `follows`.`deleted_at` is null
)
and `place_lists`.`deleted_at` is null
order by (
select
`created_at`
from
`follows`
where
`created_by_user_id` = 13
and `followable_id` = `place_lists`.`id`
and `follows`.`deleted_at` is null
) desc
I'm well confused, what I'm doing wrong?

Answer 1

This query, you assert that followalbe_id is equal to 'place_lists.id'.
->orderByDesc(
Follow::query()->select('created_at')
->where('created_by_user_id', $userID)
->where('followable_id', 'place_lists.id')
)
To compare two columns use whereColumn() instead.
->orderByDesc(
Follow::query()->select('created_at')
->where('created_by_user_id', $userID)
->whereColumn('followable_id', 'place_lists.id')
)

Answer 2

I'm not sure if I'm on the right track here but in line 9 of your eloquent builder the query generated will use a string to compare followable_id against and therefore look like this:
and `followable_id` = 'place_lists.id'
Using DB::raw() in your where-clause in line 9 should fix that:
$myQuery = PlaceList::query()
->where('private', 0)
->whereHas('followers', function ($query) use ($userID) {
$query->where('created_by_user_id', $userID);
})
->orderByDesc(
Follow::query()->select('created_at')
->where('created_by_user_id', $userID)
->where('followable_id', DB::raw('`place_lists`.`id`')) // here
)
->get()