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module ActiveRecord
module Associations
class AssociationScope #:nodoc:
def self.scope(association, connection)
INSTANCE.scope(association, connection)
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, connection)
klass = association.klass
reflection = association.reflection
scope = klass.unscoped
owner = association.owner
alias_tracker = AliasTracker.create connection, association.klass.table_name, klass.type_caster
chain_head, chain_tail = get_chain(reflection, association, alias_tracker)
scope.extending! Array(reflection.options[:extend])
add_constraints(scope, owner, klass, reflection, chain_head, chain_tail)
end
def join_type
Arel::Nodes::InnerJoin
end
def self.get_bind_values(owner, chain)
binds = []
last_reflection = chain.last
binds << last_reflection.join_id_for(owner)
if last_reflection.type
binds << owner.class.base_class.name
end
chain.each_cons(2).each do |reflection, next_reflection|
if reflection.type
binds << next_reflection.klass.base_class.name
end
end
binds
end
protected
attr_reader :value_transformation
private
def join(table, constraint)
table.create_join(table, table.create_on(constraint), join_type)
end
def last_chain_scope(scope, table, reflection, owner, association_klass)
join_keys = reflection.join_keys(association_klass)
key = join_keys.key
foreign_key = join_keys.foreign_key
value = transform_value(owner[foreign_key])
scope = scope.where(table.name => { key => value })
if reflection.type
polymorphic_type = transform_value(owner.class.base_class.name)
scope = scope.where(table.name => { reflection.type => polymorphic_type })
end
scope
end
def transform_value(value)
value_transformation.call(value)
end
def next_chain_scope(scope, table, reflection, association_klass, foreign_table, next_reflection)
join_keys = reflection.join_keys(association_klass)
key = join_keys.key
foreign_key = join_keys.foreign_key
constraint = table[key].eq(foreign_table[foreign_key])
if reflection.type
value = transform_value(next_reflection.klass.base_class.name)
scope = scope.where(table.name => { reflection.type => value })
end
scope = scope.joins(join(foreign_table, constraint))
end
class ReflectionProxy < SimpleDelegator # :nodoc:
attr_accessor :next
attr_reader :alias_name
def initialize(reflection, alias_name)
super(reflection)
@alias_name = alias_name
end
def all_includes; nil; end
end
def get_chain(reflection, association, tracker)
name = reflection.name
runtime_reflection = Reflection::RuntimeReflection.new(reflection, association)
previous_reflection = runtime_reflection
reflection.chain.drop(1).each do |refl|
alias_name = tracker.aliased_table_for(refl.table_name, refl.alias_candidate(name))
proxy = ReflectionProxy.new(refl, alias_name)
previous_reflection.next = proxy
previous_reflection = proxy
end
[runtime_reflection, previous_reflection]
end
def add_constraints(scope, owner, association_klass, refl, chain_head, chain_tail)
owner_reflection = chain_tail
table = owner_reflection.alias_name
scope = last_chain_scope(scope, table, owner_reflection, owner, association_klass)
reflection = chain_head
while reflection
table = reflection.alias_name
unless reflection == chain_tail
next_reflection = reflection.next
foreign_table = next_reflection.alias_name
scope = next_chain_scope(scope, table, reflection, association_klass, foreign_table, next_reflection)
end
# Exclude the scope of the association itself, because that
# was already merged in the #scope method.
reflection.constraints.each do |scope_chain_item|
item = eval_scope(reflection.klass, scope_chain_item, owner)
if scope_chain_item == refl.scope
scope.merge! item.except(:where, :includes)
end
reflection.all_includes do
scope.includes! item.includes_values
end
scope.unscope!(*item.unscope_values)
scope.where_clause += item.where_clause
scope.order_values |= item.order_values
end
reflection = reflection.next
end
scope
end
def eval_scope(klass, scope, owner)
klass.unscoped.instance_exec(owner, &scope)
end
end
end
end
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