Question

I’m trying to create a simple merch association between two Products. I’ve followed a few tutorials and think I have it right, but it keep throwing an error whenever I try to add an associated item directly. I’m new to ROR, could someone help me understand what I’ve done wrong here?

class Product < ActiveRecord::Base
  attr_accessible :assoc_product,:product_id, :merch_associations, :aux_description,    :buyable, :long_description, :thumb_url, :full_url, :name, :on_special, :part_number,  :release_date, :short_description, :withdraw_date, :occasion
  has_and_belongs_to_many :categories
  has_many :merch_associations
  has_many :assoc_products, :through => :merch_associations



searchable do
text :aux_description, :long_description, :name, :on_special, :part_number, :short_description
text :categories do 
  categories.map { |category| category.name }
end

        text :occasion

        string :categories, :multiple => true do
        categories.map {|category| category.name }
    end
    string :occasion
    time :release_date

  end
end

class MerchAssociation < ActiveRecord::Base
  attr_accessible :assoc_product, :product_id  
  belongs_to :product
  belongs_to :assoc_product, :class_name => "Product"
end

Then in rails console:

Product.find(1).assoc_products.create(Product.last, :association_type => 'up_sell')
Product Load (0.3ms)  SELECT `products`.* FROM `products` WHERE `products`.`id` = 1 LIMIT 1
Product Load (0.3ms)  SELECT `products`.* FROM `products` ORDER BY `products`.`id` DESC LIMIT 1
(0.0ms)  BEGIN
(0.1ms)  ROLLBACK
NoMethodError: undefined method `stringify_keys' for #<Product:0x007fc20d1ffd70>....

Answer 1

You can’t add object to relation by create, create method is for creating new objects with provided attributes. Read here: undefined method `stringify_keys!' ruby on rails

Use Product.find(1).assoc_product << Product.last instead.

What is association_type param in your example? I guess you want to add related object with attributes for MerchAssocation? If so write:

Product.find(1).merch_associations.create(:assoc_product=>Product.last,:association_type => 'up_sell')