Ndtyjky

I have a Flag model which is joined to multiple other objects with FlagInstance and a polymorphic flaggable on that table:

table 'flag_instances'

flag_id

flaggable_id

flaggable_type

.....

With has many_through I'm able to fetch any flaggable object like user.flags which is great.

However I'm trying to flag objects with errors and the notify other objects so I've added

table 'flag_instances'

flag_id

flaggable_id

flaggable_type

notifiable_id

notifiable_type

.....

The problem is, a User can have a flag and can be notified of a flag. So user.flags isn't specific enough to show me which is a flag and which is a notification of a flag.

I think I need to change the relationships:

user.rb

has_many :flag_instances, as: :flaggable, dependent: :destroy

has_many :flags, through: :flag_instances

has_many :flag_instances, as: :notifiable, dependent: :destroy

has_many :flags, through: :flag_instances

But I'm not sure what to change them to. Can someone please suggest a solution?

Note: both flags and notifications of flags can belong to multiple objects, so they both need to remain polymorphic.

Thanks

Association for notifiable needs to be changed. In this case user.rb:

has_many :flag_instances, as: :flaggable, dependent: :destroy

has_many :flags, through: :flag_instances



has_many :notifiables, as: :notifiable, dependent: :destroy, class_name: 'FlagInstance'

has_many :notifications, through: :notifiables, class_name: 'Flag'

Note: You might also need to provide foreign_key in case Rails association is not able to pick up the key itself.

Each association must have a unique name - otherwise the later definition will just overwrite the former.

Here the third line overwrites the first line:

has_many :flag_instances, as: :flaggable, dependent: :destroy

has_many :flags, through: :flag_instances

has_many :flag_instances, as: :notifiable, dependent: :destroy

To reference the correct associations we would need to setup the user model as so:

class User < ApplicationRecord

  has_many :flag_instances_as_flaggable, 

     as: :flaggable

     class_name: 'FlagInstance'

  has_many :flags_as_flaggable, 

     through: :flag_instances_as_flaggable, 

     source: :flag

  has_many :flag_instances_as_notifiable, 

     as: :notifiable

     class_name: 'FlagInstance'

  has_many :flags_as_notifiable,

     through: :flag_instances_as_notifiable,

     source: :flag

end

In your case you might want to use concerns to keep it dry:

module Flaggable

  extend ActiveSupport::Concern

  included do

    has_many :flag_instances_as_flaggable, 

      as: :flaggable,

      class_name: 'FlagInstance'

    has_many :flags_as_flaggable,

      through: :flag_instances_as_flaggable, 

      source: :flag

  end

end



module Notifiable

  extend ActiveSupport::Concern

  included do

    has_many :flag_instances_as_notifiable, 

      as: :notifiable,

      class_name: 'FlagInstance'

    has_many :flags_as_notifiable,

      through: :flag_instances_as_notifiable,

      source: :flag

  end

end



class User < ApplicationRecord

  include Flaggable

  include Notifiable

end