Module: ActiveRecord::Associations::ThroughAssociation
Relationships & Source Files | |
Extension / Inclusion / Inheritance Descendants | |
Included In:
| |
Defined in: | activerecord/lib/active_record/associations/through_association.rb |
Overview
Active Record Through Association
Instance Attribute Summary
- #source_reflection readonly
- #foreign_key_present? ⇒ Boolean readonly private
Instance Method Summary
- #build_record(attributes) private
-
#construct_join_attributes(*records)
private
Construct attributes for
:through
pointing to owner and associate. - #ensure_mutable private
- #ensure_not_nested private
-
#stale_state
private
Note: this does not capture all cases, for example it would be impractical to try to properly support stale-checking for nested associations.
-
#target_scope
private
We merge in these scopes for two reasons:
- #through_association private
- #through_reflection private
- #transaction(&block) private
Instance Attribute Details
#foreign_key_present? ⇒ Boolean
(readonly, private)
[ GitHub ]
# File 'activerecord/lib/active_record/associations/through_association.rb', line 90
def foreign_key_present? through_reflection.belongs_to? && Array(through_reflection.foreign_key).all? do |foreign_key_column| !owner[foreign_key_column].nil? end end
#source_reflection (readonly)
[ GitHub ]# File 'activerecord/lib/active_record/associations/through_association.rb', line 7
delegate :source_reflection, to: :reflection
Instance Method Details
#build_record(attributes) (private)
[ GitHub ]# File 'activerecord/lib/active_record/associations/through_association.rb', line 116
def build_record(attributes) if source_reflection.collection? inverse = source_reflection.inverse_of target = through_association.target if inverse && target && !target.is_a?(Array) Array(target.id).zip(Array(inverse.foreign_key)).map do |primary_key_value, foreign_key_column| attributes[foreign_key_column] = primary_key_value end end end super end
#construct_join_attributes(*records) (private)
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 have 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.
# File 'activerecord/lib/active_record/associations/through_association.rb', line 57
def construct_join_attributes(*records) ensure_mutable association_primary_key = source_reflection.association_primary_key(reflection.klass) if Array(association_primary_key) == reflection.klass.composite_query_constraints_list && ! [:source_type] join_attributes = { source_reflection.name => records } else assoc_pk_values = records.map { |record| record._read_attribute(association_primary_key) } join_attributes = { source_reflection.foreign_key => assoc_pk_values } end if [:source_type] join_attributes[source_reflection.foreign_type] = [ [:source_type] ] end if records.count == 1 join_attributes.transform_values!(&:first) else join_attributes end end
#ensure_mutable (private)
[ GitHub ]# File 'activerecord/lib/active_record/associations/through_association.rb', line 96
def ensure_mutable unless source_reflection.belongs_to? if reflection.has_one? raise HasOneThroughCantAssociateThroughHasOneOrManyReflection.new(owner, reflection) else raise HasManyThroughCantAssociateThroughHasOneOrManyReflection.new(owner, reflection) end end end
#ensure_not_nested (private)
[ GitHub ]# File 'activerecord/lib/active_record/associations/through_association.rb', line 106
def ensure_not_nested if reflection.nested? if reflection.has_one? raise HasOneThroughNestedAssociationsAreReadonly.new(owner, reflection) else raise HasManyThroughNestedAssociationsAreReadonly.new(owner, reflection) end end end
#stale_state (private)
Note: this does not capture all cases, for example it would be impractical to try to properly support stale-checking for nested associations.
# File 'activerecord/lib/active_record/associations/through_association.rb', line 82
def stale_state if through_reflection.belongs_to? Array(through_reflection.foreign_key).filter_map do |foreign_key_column| owner[foreign_key_column] end.presence end end
#target_scope (private)
We merge in these scopes for two reasons:
1. To get the default_scope conditions for any of the other reflections in the chain
2. To get the type conditions for any STI models in the chain
# File 'activerecord/lib/active_record/associations/through_association.rb', line 34
def target_scope scope = super reflection.chain.drop(1).each do |reflection| relation = reflection.klass.scope_for_association scope.merge!( relation.except(:select, :create_with, :includes, :preload, :eager_load, :joins, :left_outer_joins) ) end scope end
#through_association (private)
[ GitHub ]# File 'activerecord/lib/active_record/associations/through_association.rb', line 26
def through_association @through_association ||= owner.association(through_reflection.name) end
#through_reflection (private)
[ GitHub ]# File 'activerecord/lib/active_record/associations/through_association.rb', line 14
def through_reflection @through_reflection ||= begin refl = reflection.through_reflection while refl.through_reflection? refl = refl.through_reflection end refl end end
#transaction(&block) (private)
[ GitHub ]# File 'activerecord/lib/active_record/associations/through_association.rb', line 10
def transaction(&block) through_reflection.klass.transaction(&block) end