/usr/lib/ruby/vendor_ruby/sequel/plugins/tactical_eager_loading.rb is in ruby-sequel 4.1.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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module Plugins
# The tactical_eager_loading plugin allows you to eagerly load
# an association for all objects retrieved from the same dataset
# without calling eager on the dataset. If you attempt to load
# associated objects for a record and the association for that
# object is currently not cached, it assumes you want to get
# the associated objects for all objects retrieved with the dataset that
# retrieved the current object.
#
# Tactical eager loading only takes affect if you retrieved the
# current object with Dataset#all, it doesn't work if you
# retrieved the current object with Dataset#each.
#
# Basically, this allows the following code to issue only two queries:
#
# Album.filter{id<100}.all do |a|
# a.artists
# end
#
# Usage:
#
# # Make all model subclass instances use tactical eager loading (called before loading subclasses)
# Sequel::Model.plugin :tactical_eager_loading
#
# # Make the Album class use tactical eager loading
# Album.plugin :tactical_eager_loading
module TacticalEagerLoading
module InstanceMethods
# The dataset that retrieved this object, set if the object was
# reteived via Dataset#all.
attr_accessor :retrieved_by
# All model objects retrieved with this object, set if the object was
# reteived via Dataset#all.
attr_accessor :retrieved_with
private
# If there the association is not in the associations cache and the object
# was reteived via Dataset#all, eagerly load the association for all model
# objects retrieved with the current object.
def load_associated_objects(opts, reload=false)
name = opts[:name]
if !associations.include?(name) && retrieved_by && !frozen?
begin
retrieved_by.send(:eager_load, retrieved_with.reject{|o| o.frozen?}, name=>{})
rescue Sequel::UndefinedAssociation
# This can happen if class table inheritance is used and the association
# is only defined in a subclass. This particular instance can use the
# association, but it can't be eagerly loaded as the parent class doesn't
# have access to the association, and that's the class doing the eager loading.
nil
end
end
super
end
end
module DatasetMethods
private
# Set the retrieved_with and retrieved_by attributes for the object
# with the current dataset and array of all objects.
def post_load(objects)
super
objects.each do |o|
next unless o.is_a?(Sequel::Model)
o.retrieved_by = self
o.retrieved_with = objects
end
end
end
end
end
end
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