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module ActiveRecord
# = Active Record Through Association
module Associations
module ThroughAssociation #:nodoc:
protected
def target_scope
super.merge(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.association_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.active_record_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. 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 reflection.source_reflection.macro != :belongs_to
raise HasManyThroughCantAssociateThroughHasOneOrManyReflection.new(owner, reflection)
end
join_attributes = {
reflection.source_reflection.foreign_key =>
records.map { |record|
record.send(reflection.source_reflection.association_primary_key)
}
}
if reflection.options[:source_type]
join_attributes[reflection.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
# 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(interpolate(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 = interpolate(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
|
