Failing validations in join model when using has_many :through

Question

My full code can be seen at https://github.com/andyw8/simpleform_examples

I have a join model ProductCategory with the following validations:

Answer 1

Pretty sure you just need to define your relationships better. I still might have missed some, but hopefully you get the idea.

class Product < ActiveRecord::Base
  include ActiveModel::ForbiddenAttributesProtection

  validates :name, presence: true
  validates :description, presence: true
  validates :color_scheme, presence: true

  belongs_to :color_scheme

  has_many :product_categories, inverse_of: :product
  has_many :categories, through: :product_categories
end


class ProductCategory < ActiveRecord::Base
  belongs_to :product
  belongs_to :category

  validates_associated :product
  validates_associated :category

  # TODO work out why this causes ProductsController#create to fail
  # validates :product, presence: true
  # validates :category, presence: true
end


class Category < ActiveRecord::Base
  has_many :product_categories, inverse_of: :category
  has_many :products, through: :product_categories
end