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module ActiveRecord
module Associations
class Preloader
module ThroughAssociation #:nodoc:
def through_reflection
reflection.through_reflection
end
def source_reflection
reflection.source_reflection
end
def associated_records_by_owner(preloader)
return @associated_records_by_owner if @associated_records_by_owner
preloader.preload(owners,
through_reflection.name,
through_scope)
should_reset = (through_scope != through_reflection.klass.unscoped) ||
(reflection.options[:source_type] && through_reflection.collection?)
through_records = owners.map do |owner, h|
association = owner.association through_reflection.name
[owner, Array(association.reader), association]
end
# Dont cache the association - we would only be caching a subset
if should_reset
through_records.each { |(_,_,assoc)| assoc.reset }
end
middle_records = through_records.map { |(_,rec,_)| rec }.flatten
preloaders = preloader.preload(middle_records,
source_reflection.name,
reflection_scope)
middle_to_pl = preloaders.each_with_object({}) do |pl,h|
pl.owners.each { |middle|
h[middle] = pl
}
end
@associated_records_by_owner = through_records.each_with_object({}) { |(lhs,center),records_by_owner|
pl_to_middle = center.group_by { |record| middle_to_pl[record] }
records_by_owner[lhs] = pl_to_middle.flat_map do |pl, middles|
rhs_records = middles.flat_map { |r|
r.send(source_reflection.name)
}.compact
loaded_records = pl.preloaded_records
i = 0
record_index = loaded_records.each_with_object({}) { |r,indexes|
indexes[r] = i
i += 1
}
rhs_records.sort_by { |rhs| record_index[rhs] }
end
}
end
private
def through_scope
scope = through_reflection.klass.unscoped
if options[:source_type]
scope.where! reflection.foreign_type => options[:source_type]
else
unless reflection_scope.where_values.empty?
scope.includes_values = Array(reflection_scope.values[:includes] || options[:source])
scope.where_values = reflection_scope.values[:where]
end
scope.references! reflection_scope.values[:references]
scope.order! reflection_scope.values[:order] if scope.eager_loading?
end
scope
end
end
end
end
end
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