How to use has_many through association with additional attributes

Question

Looking at the documentation on associations, I've managed to set up my classes to use has_many, :through . However, I can't seem to find any example on how to actually use the association.

My User model has_many :attendees and has_many :events, through: :attendees . My Event model has_many :attendees and has_many :users, through: :attendees .

Attendee model:

class Attendee < ActiveRecord::Base
  attr_accessible :status
  validates_inclusion_of :status, in: [:performing, :invited, :going, :maybe]

  belongs_to :user
  belongs_to :event

  def status
    read_attribute(:status).to_sym
  end

  def status=(value)
    write_attribute(:status, value.to_s)
  end
end

I tried using the following code:

at1 = Attendee.new(user: u1, event: e1)
at1.status = :invited
at1.save

Unsurprisingly, I get a mass assignment error with user and event . It seems besides the point to declare attr_accesible for user and event though. how would I use the association here, and set the custom status attribute?

Answer 1

It's absolutely not beside the point to declare attr_accessible . That's what you're missing.

Keep in mind attr_accessor is something else. For more on this, check: Difference between attr_accessor and attr_accessible

Also keep in mind that attr_accessible has been deprecated in Rails 4 in favor of Strong Parameters , effectively moving all whitelisting of attributes from the models to the controllers.