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module ActiveRecord
# = Active Record Through Association
module Associations
module ThroughAssociation
protected
def target_scope
super & @reflection.through_reflection.klass.scoped
end
def association_scope
scope = super.joins(construct_joins)
scope = add_conditions(scope)
unless @reflection.options[:include]
scope = scope.includes(@reflection.source_reflection.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
def aliased_through_table
name = @reflection.through_reflection.table_name
@reflection.table_name == name ?
@reflection.through_reflection.klass.arel_table.alias(name + "_join") :
@reflection.through_reflection.klass.arel_table
end
def construct_owner_conditions
super(aliased_through_table, @reflection.through_reflection)
end
def construct_joins
right = aliased_through_table
left = @reflection.klass.arel_table
conditions = []
if @reflection.source_reflection.macro == :belongs_to
reflection_primary_key = @reflection.source_reflection.options[:primary_key] ||
@reflection.klass.primary_key
source_primary_key = @reflection.source_reflection.foreign_key
if @reflection.options[:source_type]
column = @reflection.source_reflection.foreign_type
conditions <<
right[column].eq(@reflection.options[:source_type])
end
else
reflection_primary_key = @reflection.source_reflection.foreign_key
source_primary_key = @reflection.source_reflection.options[:primary_key] ||
@reflection.through_reflection.klass.primary_key
if @reflection.source_reflection.options[:as]
column = "#{@reflection.source_reflection.options[:as]}_type"
conditions <<
left[column].eq(@reflection.through_reflection.klass.name)
end
end
conditions <<
left[reflection_primary_key].eq(right[source_primary_key])
right.create_join(
right,
right.create_on(right.create_and(conditions)))
end
# Construct attributes for :through pointing to owner and associate.
def construct_join_attributes(associate)
# TODO: revisit this to allow it for deletion, supposing dependent option is supported
raise ActiveRecord::HasManyThroughCantAssociateThroughHasOneOrManyReflection.new(@owner, @reflection) if [:has_one, :has_many].include?(@reflection.source_reflection.macro)
join_attributes = {
@reflection.source_reflection.foreign_key =>
associate.send(@reflection.source_reflection.association_primary_key)
}
if @reflection.options[:source_type]
join_attributes.merge!(@reflection.source_reflection.foreign_type => associate.class.base_class.name)
end
if @reflection.through_reflection.options[:conditions].is_a?(Hash)
join_attributes.merge!(@reflection.through_reflection.options[:conditions])
end
join_attributes
end
# The reason that we are operating directly on the scope here (rather than passing
# back some arel conditions to be added to the scope) is because scope.where([x, y])
# has a different meaning to scope.where(x).where(y) - the first version might
# perform some substitution if x is a string.
def add_conditions(scope)
unless @reflection.through_reflection.klass.descends_from_active_record?
scope = scope.where(@reflection.through_reflection.klass.send(:type_condition))
end
scope = scope.where(@reflection.source_reflection.options[:conditions])
scope.where(through_conditions)
end
# If there is a hash of conditions then we make sure the keys are scoped to the
# through table name if left ambiguous.
def through_conditions
conditions = @reflection.through_reflection.options[:conditions]
if conditions.is_a?(Hash)
Hash[conditions.map { |key, value|
unless value.is_a?(Hash) || key.to_s.include?('.')
key = aliased_through_table.name + '.' + key.to_s
end
[key, value]
}]
else
conditions
end
end
def stale_state
if @reflection.through_reflection.macro == :belongs_to
@owner[@reflection.through_reflection.foreign_key].to_s
end
end
def foreign_key_present?
@reflection.through_reflection.macro == :belongs_to &&
!@owner[@reflection.through_reflection.foreign_key].nil?
end
end
end
end
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