app/serializers/membership_serializer.rb
class MembershipSerializer < ActiveModel::Serializer
embed :ids, include: true
attributes :id,
:is_admin,
:created_at,
:balance,
:archived_at,
:raw_balance,
:closed_admin_help_card_at,
:closed_member_help_card_at
has_one :member, serializer: UserSerializer, root: 'users'
has_one :group, serializer: GroupSerializer, root: 'groups'
end