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# frozen_string_literal: true
module ActiveRecord
module Associations
class Preloader
class Association #:nodoc:
attr_reader :preloaded_records
def initialize(klass, owners, reflection, preload_scope)
@klass = klass
@owners = owners
@reflection = reflection
@preload_scope = preload_scope
@model = owners.first && owners.first.class
@preloaded_records = []
end
def run(preloader)
records = load_records do |record|
owner = owners_by_key[convert_key(record[association_key_name])]
association = owner.association(reflection.name)
association.set_inverse_instance(record)
end
owners.each do |owner|
associate_records_to_owner(owner, records[convert_key(owner[owner_key_name])] || [])
end
end
private
attr_reader :owners, :reflection, :preload_scope, :model, :klass
# The name of the key on the associated records
def association_key_name
reflection.join_primary_key(klass)
end
# The name of the key on the model which declares the association
def owner_key_name
reflection.join_foreign_key
end
def associate_records_to_owner(owner, records)
association = owner.association(reflection.name)
if reflection.collection?
association.loaded!
association.target.concat(records)
else
association.target = records.first
end
end
def owner_keys
@owner_keys ||= owners_by_key.keys
end
def owners_by_key
unless defined?(@owners_by_key)
@owners_by_key = owners.each_with_object({}) do |owner, h|
key = convert_key(owner[owner_key_name])
h[key] = owner if key
end
end
@owners_by_key
end
def key_conversion_required?
unless defined?(@key_conversion_required)
@key_conversion_required = (association_key_type != owner_key_type)
end
@key_conversion_required
end
def convert_key(key)
if key_conversion_required?
key.to_s
else
key
end
end
def association_key_type
@klass.type_for_attribute(association_key_name).type
end
def owner_key_type
@model.type_for_attribute(owner_key_name).type
end
def load_records(&block)
return {} if owner_keys.empty?
# Some databases impose a limit on the number of ids in a list (in Oracle it's 1000)
# Make several smaller queries if necessary or make one query if the adapter supports it
slices = owner_keys.each_slice(klass.connection.in_clause_length || owner_keys.size)
@preloaded_records = slices.flat_map do |slice|
records_for(slice, &block)
end
@preloaded_records.group_by do |record|
convert_key(record[association_key_name])
end
end
def records_for(ids, &block)
scope.where(association_key_name => ids).load(&block)
end
def scope
@scope ||= build_scope
end
def reflection_scope
@reflection_scope ||= reflection.scope ? reflection.scope_for(klass.unscoped) : klass.unscoped
end
def build_scope
scope = klass.scope_for_association
if reflection.type
scope.where!(reflection.type => model.base_class.name)
end
scope.merge!(reflection_scope) if reflection.scope
scope.merge!(preload_scope) if preload_scope
scope
end
end
end
end
end
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