Join table for has_many through in Rails

Question

I am new to programming & rails and there\'s something I dont fully understand. I am creating an app with

product has_many categories
category has_many produ         


        

Answer 1

You also have to add CategoryProduct to each model:

class Product < ActiveRecord::Base
  has_many :category_products
  has_many :categories, through: :category_product

It is very simple using gem simple form. All you have to do is to add:

t.association :categories

in a form for product and add :category_ids => [] to a list of permitted parameters in your products controller

If you prefer checkboxes instead of multi-select list, you can do

    t.association :categories, as: check_boxes

And the last thing, to display categories in human-readable format, you need to define a to_s method in your category model, i. e.:

class Category < ActiveRecord::Base
  ...
  def to_s
    name
  end 
end