[ruby-on-rails] How do you discover model attributes in Rails?

If you're just interested in the properties and data types from the database, you can use Model.inspect.

irb(main):001:0> User.inspect
=> "User(id: integer, email: string, encrypted_password: string,
 reset_password_token: string, reset_password_sent_at: datetime,
 remember_created_at: datetime, sign_in_count: integer,
 current_sign_in_at: datetime, last_sign_in_at: datetime,
 current_sign_in_ip: string, last_sign_in_ip: string, created_at: datetime,
 updated_at: datetime)"

Alternatively, having run rake db:create and rake db:migrate for your development environment, the file db/schema.rb will contain the authoritative source for your database structure:

ActiveRecord::Schema.define(version: 20130712162401) do
  create_table "users", force: true do |t|
    t.string   "email",                  default: "", null: false
    t.string   "encrypted_password",     default: "", null: false
    t.string   "reset_password_token"
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.integer  "sign_in_count",          default: 0
    t.datetime "current_sign_in_at"
    t.datetime "last_sign_in_at"
    t.string   "current_sign_in_ip"
    t.string   "last_sign_in_ip"
    t.datetime "created_at"
    t.datetime "updated_at"
  end
end