rails g migration references code example

Example 1: Add references rails migration

rails g migration AddUserToUploads user:references

Example 2: Add references rails migration

class AddUserToUploads < ActiveRecord::Migration
  def change
    add_reference :uploads, :user, index: true
  end
end

Example 3: rails g migration add columns

$ rails generate migration AddDetailsToProducts part_number:string price:decimal

Example 4: rails g migration foreign key optionnal

#MODEL
belongs_to :author, optional: true

#MIGRATION
t.references :author, foreign_key: true