Module: EdgeRider::TraverseAssociation

Extended by:
TraverseAssociation
Included in:
TraverseAssociation
Defined in:
lib/edge_rider/traverse_association.rb

Defined Under Namespace

Classes: UnknownAssociation, UnsupportedAssociation

Instance Method Summary collapse

Instance Method Details

#traverse_association(*associations) ⇒ Object 



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# File 'lib/edge_rider/traverse_association.rb', line 7

def traverse_association(*associations)

  scope = scoped({})

  associations.each do |association|

    reflection = scope.reflect_on_association(association) or raise UnknownAssociation, "Could not find association: #{self.name}##{association}"
    foreign_key = reflection.respond_to?(:foreign_key) ? reflection.foreign_key : reflection.primary_key_name

    # In Rails 4, conditions on a scope are expressed as a lambda parameter
    # that is called `scope`.
    raise NotImplementedError if reflection.options[:conditions] or (reflection.respond_to?(:scope) && reflection.scope)
       
    if reflection.macro == :belongs_to # belongs_to
      ids = scope.collect_column(foreign_key, distinct: true)
      scope = EdgeRider::Util.exclusive_query(reflection.klass, id: ids)
    elsif reflection.macro == :has_many || reflection.macro == :has_one
      if reflection.through_reflection # has_many :through
        scope = scope.traverse_association(reflection.through_reflection.name, reflection.source_reflection.name)
      else # has_many or has_one
        conditions = {}
        # A polymorphic association has a type attribute, e.g. record_type, that needs to be added to condition.
        conditions[reflection.type] = self.name if reflection.type.present?
        conditions[foreign_key] = scope.collect_ids

        scope = EdgeRider::Util.exclusive_query(reflection.klass, conditions)
      end
    else
      raise UnsupportedAssociation, "Unsupport association type: #{reflection.macro}"
    end
  end

  scope

end