ruby on rails - How to model an owner and members with a has_many :through association? -

in rails application have event , user models. business rules dictate event has 1 owner , many members, , owner must member. inverse user having many 'owned events' , 'events' (events he/she member of not owner). had planned model association so:

class event < activerecord::base   has_many :event_members, dependent: :destroy    has_one :owner, through: :event_members, source: :user, conditions: { owner: true }   has_many :members, through: :event_members, source: :user end  class eventmember < activerecord::base   belongs_to :event   belongs_to :user end  class user < activerecord::base   has_many :owned_events, through: :event_members, conditions: { owner: true }   has_many :events, through: :event_members end 

i thought ensure 1 owner , owner included in members association free. however, doesn't work since can't specify has_one through collection - :event_members association.

is there better way model this? add transient 'owner' attr on event queries eventmember owner flag - work setting owner (i.e. can grab eventmember record created , make sure owner flag set)?

what adding owner attribute on join model eventmember (also field of type boolean in event_members table, default value of false). access owner , owned_events methods on each respective model.

class event < activerecord::base                has_many :event_members   has_many :members, :through => :event_members, :source => :user    def owner                                       event_members.ownerships.map(&:user).first                                                                 end                                         end                                            class eventmember < activerecord::base          belongs_to :event                             belogns_to :user    scope :ownerships, -> { where(:owner => true) }                           end                                            class user < activerecord::base                 has_many :event_members                       has_many :events, :through => :event_members    def owned_events                                event_members.ownerships.map(&:event)         end                                         end 

the event object may have responsibility of making user owner.

class event   def make_owner!(user)     membership = event_members.where(:user_id = user).first     membership.owner = true     membership.save   end end 

maybe place logic in there enforce 1 owner , abstract part of make_owner! eventmember depending on how messy gets in application.