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# frozen_string_literal: true
module ActiveRecord
module Associations
class Preloader
class Association #:nodoc:
attr_reader :owners, :reflection, :preload_scope, :model, :klass
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)
preload(preloader)
end
def preload(preloader)
raise NotImplementedError
end
# The name of the key on the associated records
def association_key_name
raise NotImplementedError
end
# The name of the key on the model which declares the association
def owner_key_name
raise NotImplementedError
end
private
def options
reflection.options
end
def associated_records_by_owner(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_with_object({}) do |owner, result|
result[owner] = records[convert_key(owner[owner_key_name])] || []
end
end
def owner_keys
unless defined?(@owner_keys)
@owner_keys = owners.map do |owner|
owner[owner_key_name]
end
@owner_keys.uniq!
@owner_keys.compact!
end
@owner_keys
end
def owners_by_key
unless defined?(@owners_by_key)
@owners_by_key = owners.each_with_object({}) do |owner, h|
h[convert_key(owner[owner_key_name])] = owner
end
end
@owners_by_key
end
def key_conversion_required?
@key_conversion_required ||= association_key_type != owner_key_type
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.to_s).type
end
def owner_key_type
@model.type_for_attribute(owner_key_name.to_s).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.size == 1 ? ids.first : ids).load(&block)
end
def scope
@scope ||= build_scope
end
def reflection_scope
@reflection_scope ||= reflection.scope_for(klass)
end
def klass_scope
current_scope = klass.current_scope
if current_scope && current_scope.empty_scope?
klass.unscoped
else
klass.default_scoped
end
end
def build_scope
scope = klass_scope
if reflection.type
scope.where!(reflection.type => model.base_class.sti_name)
end
scope.merge!(reflection_scope)
scope.merge!(preload_scope) if preload_scope
scope
end
end
end
end
end
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