Ruby on Rails -- Using multiple has_many associations to the same model -

i have simple program event can created user, , event class knows created it:

class event < activerecord::base    # owner of event   belongs_to :user  end  class user < activerecord::base    # user has 0 n created events   has_many :events  end 

so far good, correct association behaviour when call "event.user" example, , creator of event can perform crud operations on his/her event.

however want ability user save events (not in database sense, can view in dashboard or such), , want use these 2 models. tried adding "user_saved_id" event model new column keep track of users save following:

class event < activerecord::base    # owner of event   belongs_to :user  end  class user < activerecord::base    # user has 0 n created events   has_many :events    # user has 0 n saved events, including created event   has_many :saved_events, foreign_key: 'user_saved_id', class_name: "event"  end 

however having no such luck. when try initialize event creator have automatically saved his/her own event when he/she creates example, " undefined method `each' " in create method below (i using devise gem, , "current_user" helper function returns id of current signed in user):

# post /events # post /events.json   def create     @event = event.new(event_params)      # associate event creator, works correctly     @event.user = current_user      # initialize user have saved own events, not working     @event.user.saved_events = current_user  ... 

i appreciate pointers can on getting wrong, if got association relationship wrong, , if overthinking , there simpler way go it. in advance.

the problem adding user event user_saved_id, 1 user ever able save event. if understand correctly, user able save events (that may or may not have created?) shown in dashboard. in case going need has_and_belongs_to_many or has_many through type relationship, , table. perhaps using has_many through.

class savedevent < activerecord::base   belongs_to :user   belongs_to :event  end   class user < activerecord::base   # user has 0 n created events   has_many :events   has_many :saved_events    # user has 0 n saved events through favorites table   has_many :later_events,  through: :saved_events   end  

when create savedevent, can use created_at timestamp show when user saved it, or can store other information/metadata saving it.

having reverse set event allow list of users have saved event via event.saved_users. (sorry naming things 1 of hard problems)

class event < activerecord::base    # owner of event   belongs_to :user   has_many :saved_events   has_many :saved_users, through: :saved_events   end 

then creating new event be

def create   #wrap in transaction    event.transaction    #build event through association      @event = current_user.events.create!(event_params)    #save current users saved events    current_user.saved_events.create!(event: @event)   end   end 

the transaction , ! methods make roll if cannot create event , add saved events, , not wind event isn't in saved/later events table when created.

when user wants save event, in controller that, need current_user.saved_events.create(event: event) them, , save it.

then in dashboard can current_user.later_events , collection of events have saved.