Rails Migration Generated Join Table Schema But No File

Question

I created a join table for a HABTM association in my Rails app. It created the table in the schema, but it never generated a model file in the app. Will it still work? Why did it not generate a file?

Here is my migration:

class CreateBooksAuthorsJoinTable < ActiveRecord::Migration
  def change
    create_table :books_authors, id: false do |t|
      t.integer :book_id
      t.integer :author_id

      t.timestamps
    end
  end
end

Models

class Book < ActiveRecord::Base
    has_and_belongs_to_many :feeds
end

class Author < ActiveRecord::Base
  has_and_belongs_to_many :posts
end

Answer 1

You would have to explicitly generate a model; it doesn't happen as a by-product of creating a join table.

A has_and_belongs_to_many association doesn't actually need a model class representing the association. It is supposed to be just a join table so what you've set up is exactly right.

The other option for such associations is a has_many through: association which uses an intermediate, or join, class. This is discussed in more details in the rails guide for associations. You would have to generate that joining model yourself though.