You should not expect to be able to generate your app via scaffolding alone. It is meant only to provide an example for getting started.
The most flexible kind of many-to-many relationship in rails is called [has many through](
[To see links please register here]
). This requires a join table which would typically be called 'categorisations' in this case. It would need a `product_id` column declared as `belongs to :product` and a `category_id` column declared as `belongs_to :category`. The three models (including the join model) would be declared thus:
# Table name: products
# Columns:
# name:string
class Product < ActiveRecord::Base
has_many :categorisations, dependent: :destroy
has_many :categories, through: :categorisations
end
# Table name: categories
# Columns:
# name:string
class Category < ActiveRecord::Base
has_many :categorisations, dependent: :destroy
has_many :products, through: :categorisations
end
# Table name: categorisations
# Columns:
# product_id:integer
# category_id:integer
class Categorisation < ActiveRecord::Base
belongs_to :product
belongs_to :category
end
Note that I've named the columns `name` rather than `prd_name` since this is both human-readable and avoids redundant repetition of the table name. This is highly recommended when using rails.
The models can be generated like this:
rails generate model product name
rails generate model category name
rails generate model categorisation product:references category:references
As for generating the scaffolding, you could replace `model` with `scaffold` in the first two commands. Again though, I don't recommend it except as a way to see an example to learn from.
]
