tactical eagerloading, inheritance plugins, and subclasses with different associations that have the same name

[sterlzbd]

In 5.63.0, tactical eagerloading was made to work with class table inheritance (here #1962). However, it doesn't support subclasses with different associations that have the same name (which was explicitly noted here: 9a9f111)

We have an existing schema that is relying that behavior (so we're still using 5.62.0). We're getting around to upgrading Sequel so I'm wondering if you'd consider handling that case for tactical eagerloading or have another suggestion.

Here is small demo to illustrate:

DB.create_table :albums do
  primary_key :id
  column :title, :text
  column :release_date, :date
  column :type, :text, null: false
end

DB.create_table :albums_bundles do
  foreign_key :bundle_id, :albums
  foreign_key :release_id, :albums
  column :sequence, :integer, default: 1, null: false
end

DB.create_table :discs do
  primary_key :id
  foreign_key :release_id, :albums, null: false
  column :sequence, :integer, default: 1, null: false
end

Sequel::Model.plugin :tactical_eager_loading

class Album < Sequel::Model
  plugin :single_table_inheritance, :type
end

class Release < Album
  one_to_many :discs
end

class Bundle < Album
  plugin :many_through_many
  many_to_many :releases, class: "Release", join_table: :albums_bundles
  many_through_many :discs, [[:albums_bundles, :bundle_id, :release_id], [:albums, :id, :id]]
end

class AlbumsBundle < Sequel::Model
  many_to_one :bundle
  many_to_one :release
end

class Disc < Sequel::Model
  many_to_one :release, class: "Release"
end

# create a bundle with 1 release + 1 normal release that has 1 disc
normal_release = Release.create title: "Normal Release"
normal_release.add_disc Disc.create release_id: normal_release.id

child_release = Release.create title: "Child Release"
child_release.add_disc Disc.create release_id: child_release.id

bundle = Bundle.create title: "Bundle Release"
bundle.add_release child_release

puts "without eagerloading"
bundle.reload
puts bundle.title
puts "# Discs: #{bundle.discs.length}"
puts "***"
normal_release.reload
puts normal_release.title
puts "# Discs: #{normal_release.discs.length}"
puts "***"

puts "trying to use eagerloading"
main_albums = Album.where(id: [normal_release.id, bundle.id]).all
main_albums.each do |album|
  puts album.title
  puts "# Discs: #{album.discs.length}"
  puts "***"
end

Using 5.62.0, the eagerloading doesn't work but the results are accurate:

without eagerloading
Bundle Release
# Discs: 1
***
Normal Release
# Discs: 1
***
trying to use eagerloading
Normal Release
# Discs: 1
***
Bundle Release
# Discs: 1
***

After 5.63.0 tactical eagerloading kicks in but we get innacurate disc counts:

without eagerloading
Bundle Release
# Discs: 1
***
Normal Release
# Discs: 1
***
trying to use eagerloading
Normal Release
# Discs: 1
***
Bundle Release
# Discs: 0
***

Let me know what you think. Thanks!

[jeremyevans]

I guess the only thing we could do would be to detect this case and disallow eager loading. You cannot eager load unless all items being tactically eager loaded are using the same association definition.

[sterlzbd]

Yeah that makes sense.

Thanks for the quick response!

[sterlzbd]

I think for our case we could move forward by renaming one of the associations and add a method as an abstraction over it. For example, using the demo

class Bundle < Album
  plugin :many_through_many
  many_to_many :releases, class: "Release", join_table: :albums_bundles
  many_through_many :bundle_discs, [[:albums_bundles, :bundle_id, :release_id], [:albums, :id, :id]], class: "Disc", right_primary_key: :release_id

  def discs
    bundle_discs
  end
end

[jeremyevans]

Should be fixed by 68279d0

[sterlzbd]

Great, thank you!