method

construct_join_attributes

v4.2.9 - Show latest stable - Class: ActiveRecord::Associations::ThroughAssociation

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 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.

# File activerecord/lib/active_record/associations/through_association.rb, line 39
        def construct_join_attributes(*records)
          ensure_mutable

          if source_reflection.association_primary_key(reflection.klass) == reflection.klass.primary_key
            join_attributes = { source_reflection.name => records }
          else
            join_attributes = {
              source_reflection.foreign_key =>
                records.map { |record|
                  record.send(source_reflection.association_primary_key(reflection.klass))
                }
            }
          end

          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

construct_join_attributes

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