Things I learned the hard way with Rails # 1. Generate your model, make all manual edits, and only AFTER you have done this, run rake db:migrate

1_console

rails g model identity name:string email:string password_digest:string

2_GENERATED_20130616051214_create_identities.rb

class CreateIdentities < ActiveRecord::Migration
  def change
    create_table :identities do |t|
      t.string :name
      t.string :email
      t.string :password_digest

      t.timestamps
    end
  end
end

3_EDITED_20130616051214_create_identities.rb

class CreateIdentities < ActiveRecord::Migration
  def change
    create_table :identities do |t|
      t.string :name,             :null => false
      t.string :email,            :null => false
      t.string :password_digest,  :null => false

      t.timestamps
    end
  end
end

4_console

rake db:migrate