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require 'enumerator'
module ActiveRecord
# = Active Record Through Association
module Associations
module ThroughAssociation #:nodoc:
delegate :source_options, :through_options, :source_reflection, :through_reflection,
:through_reflection_chain, :through_conditions, :to => :reflection
protected
# We merge in these scopes for two reasons:
#
# 1. To get the scope_for_create on through reflection when building associated objects
# 2. To get the type conditions for any STI classes in the chain
#
# TODO: Don't actually do this. Getting the creation attributes for a non-nested through
# is a special case. The rest (STI conditions) should be handled by the reflection
# itself.
def target_scope
scope = super
through_reflection_chain[1..-1].each do |reflection|
scope = scope.merge(reflection.klass.scoped)
end
scope
end
def association_scope
scope = join_to(super)
unless options[:include]
scope = scope.includes(source_options[:include])
end
scope
end
private
# This scope affects the creation of the associated records (not the join records). At the
# moment we only support creating on a :through association when the source reflection is a
# belongs_to. Thus it's not necessary to set a foreign key on the associated record(s), so
# this scope has can legitimately be empty.
def creation_attributes
{ }
end
# TODO: Needed?
def aliased_through_table
name = through_reflection.table_name
reflection.table_name == name ?
through_reflection.klass.arel_table.alias(name + "_join") :
through_reflection.klass.arel_table
end
def construct_owner_conditions
end
def join_to(scope)
joins = []
tables = tables().dup # FIXME: Ugly
through_reflection_chain.each_with_index do |reflection, i|
table, foreign_table = tables.shift, tables.first
if reflection.source_macro == :has_and_belongs_to_many
join_table = tables.shift
joins << inner_join(
join_table,
table[reflection.active_record_primary_key].
eq(join_table[reflection.association_foreign_key])
)
table, foreign_table = join_table, tables.first
end
if reflection.source_macro == :belongs_to
key = reflection.association_primary_key
foreign_key = reflection.foreign_key
else
key = reflection.foreign_key
foreign_key = reflection.active_record_primary_key
end
if reflection == through_reflection_chain.last
constraint = table[key].eq owner[foreign_key]
scope = scope.where(constraint).where(reflection_conditions(i))
else
constraint = table[key].eq foreign_table[foreign_key]
joins << inner_join(foreign_table, constraint, reflection_conditions(i))
end
end
scope.joins(joins)
end
# Construct attributes for :through pointing to owner and associate. This is used by the
# methods which create and delete records on the association.
#
# We only support indirectly modifying through associations which has a belongs_to source.
# This is the "has_many :tags, :through => :taggings" situation, where the join model
# typically has a belongs_to on both side. In other words, associations which could also
# be represented as has_and_belongs_to_many associations.
#
# We do not support creating/deleting records on the association where the source has
# some other type, because this opens up a whole can of worms, and in basically any
# situation it is more natural for the user to just create or modify their join records
# directly as required.
def construct_join_attributes(*records)
if source_reflection.macro != :belongs_to
raise HasManyThroughCantAssociateThroughHasOneOrManyReflection.new(owner, reflection)
end
join_attributes = {
source_reflection.foreign_key =>
records.map { |record|
record.send(source_reflection.association_primary_key)
}
}
if options[:source_type]
join_attributes[source_reflection.foreign_type] =
records.map { |record| record.class.base_class.name }
end
if records.count == 1
Hash[join_attributes.map { |k, v| [k, v.first] }]
else
join_attributes
end
end
def alias_tracker
@alias_tracker ||= AliasTracker.new
end
def tables
@tables ||= begin
tables = []
through_reflection_chain.each do |reflection|
tables << alias_tracker.aliased_table_for(
reflection.table_name,
table_alias_for(reflection, reflection != self.reflection)
)
if reflection.macro == :has_and_belongs_to_many ||
(reflection.source_reflection &&
reflection.source_reflection.macro == :has_and_belongs_to_many)
tables << alias_tracker.aliased_table_for(
(reflection.source_reflection || reflection).options[:join_table],
table_alias_for(reflection, true)
)
end
end
tables
end
end
def table_alias_for(reflection, join = false)
name = alias_tracker.pluralize(reflection.name)
name << "_#{self.reflection.name}"
name << "_join" if join
name
end
def inner_join(table, *conditions)
table.create_join(
table,
table.create_on(table.create_and(conditions.flatten.compact)))
end
def reflection_conditions(index)
reflection = through_reflection_chain[index]
conditions = through_conditions[index]
unless conditions.empty?
Arel::Nodes::And.new(process_conditions(conditions, reflection))
end
end
def process_conditions(conditions, reflection)
conditions.map do |condition|
condition = reflection.klass.send(:sanitize_sql, interpolate(condition), reflection.table_name)
condition = Arel.sql(condition) unless condition.is_a?(Arel::Node)
condition
end
end
# TODO: Think about this in the context of nested associations
def stale_state
if through_reflection.macro == :belongs_to
owner[through_reflection.foreign_key].to_s
end
end
def foreign_key_present?
through_reflection.macro == :belongs_to &&
!owner[through_reflection.foreign_key].nil?
end
def ensure_not_nested
if reflection.nested?
raise HasManyThroughNestedAssociationsAreReadonly.new(owner, reflection)
end
end
end
end
end
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