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# frozen_string_literal: true
module ActiveRecord
module Associations
class AssociationScope # :nodoc:
def self.scope(association)
INSTANCE.scope(association)
end
def self.create(&block)
block ||= lambda { |val| val }
new(block)
end
def initialize(value_transformation)
@value_transformation = value_transformation
end
INSTANCE = create
def scope(association)
klass = association.klass
reflection = association.reflection
scope = klass.unscoped
owner = association.owner
chain = get_chain(reflection, association, scope.alias_tracker)
scope.extending! reflection.extensions
scope = add_constraints(scope, owner, chain)
scope.limit!(1) unless reflection.collection?
scope
end
def self.get_bind_values(owner, chain)
binds = []
last_reflection = chain.last
binds.push(*last_reflection.join_id_for(owner))
if last_reflection.type
binds << owner.class.polymorphic_name
end
chain.each_cons(2).each do |reflection, next_reflection|
if reflection.type
binds << next_reflection.klass.polymorphic_name
end
end
binds
end
private
attr_reader :value_transformation
def join(table, constraint)
Arel::Nodes::LeadingJoin.new(table, Arel::Nodes::On.new(constraint))
end
def last_chain_scope(scope, reflection, owner)
primary_key = Array(reflection.join_primary_key)
foreign_key = Array(reflection.join_foreign_key)
table = reflection.aliased_table
primary_key_foreign_key_pairs = primary_key.zip(foreign_key)
primary_key_foreign_key_pairs.each do |join_key, foreign_key|
value = transform_value(owner._read_attribute(foreign_key))
scope = apply_scope(scope, table, join_key, value)
end
if reflection.type
polymorphic_type = transform_value(owner.class.polymorphic_name)
scope = apply_scope(scope, table, reflection.type, polymorphic_type)
end
scope
end
def transform_value(value)
value_transformation.call(value)
end
def next_chain_scope(scope, reflection, next_reflection)
primary_key = Array(reflection.join_primary_key)
foreign_key = Array(reflection.join_foreign_key)
table = reflection.aliased_table
foreign_table = next_reflection.aliased_table
primary_key_foreign_key_pairs = primary_key.zip(foreign_key)
constraints = primary_key_foreign_key_pairs.map do |join_primary_key, foreign_key|
table[join_primary_key].eq(foreign_table[foreign_key])
end.inject(&:and)
if reflection.type
value = transform_value(next_reflection.klass.polymorphic_name)
scope = apply_scope(scope, table, reflection.type, value)
end
scope.joins!(join(foreign_table, constraints))
end
class ReflectionProxy < SimpleDelegator # :nodoc:
attr_reader :aliased_table
def initialize(reflection, aliased_table)
super(reflection)
@aliased_table = aliased_table
end
def all_includes; nil; end
end
def get_chain(reflection, association, tracker)
name = reflection.name
chain = [Reflection::RuntimeReflection.new(reflection, association)]
reflection.chain.drop(1).each do |refl|
aliased_table = tracker.aliased_table_for(refl.klass.arel_table) do
refl.alias_candidate(name)
end
chain << ReflectionProxy.new(refl, aliased_table)
end
chain
end
def add_constraints(scope, owner, chain)
scope = last_chain_scope(scope, chain.last, owner)
chain.each_cons(2) do |reflection, next_reflection|
scope = next_chain_scope(scope, reflection, next_reflection)
end
chain_head = chain.first
chain.reverse_each do |reflection|
reflection.constraints.each do |scope_chain_item|
item = eval_scope(reflection, scope_chain_item, owner)
if scope_chain_item == chain_head.scope
scope.merge! item.except(:where, :includes, :unscope, :order)
elsif !item.references_values.empty?
scope.merge! item.only(:joins, :left_outer_joins)
associations = item.eager_load_values | item.includes_values
unless associations.empty?
scope.joins! item.construct_join_dependency(associations, Arel::Nodes::OuterJoin)
end
end
reflection.all_includes do
scope.includes_values |= item.includes_values
end
scope.unscope!(*item.unscope_values)
scope.where_clause += item.where_clause
scope.order_values = item.order_values | scope.order_values
end
end
scope
end
def apply_scope(scope, table, key, value)
if scope.table == table
scope.where!(key => value)
else
scope.where!(table.name => { key => value })
end
end
def eval_scope(reflection, scope, owner)
relation = reflection.build_scope(reflection.aliased_table)
relation.instance_exec(owner, &scope) || relation
end
end
end
end
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