Most applications have at least two categories of users—administrators and ordinary users. Many applications have finer-grained permissions, but this is a good place to start. Code for this is available in ch14/students008. The first step toward creating an extra category of users is to create a migration with a suitable name:
script/generate migration AddAdminFlagToUsers
In the newly created migration, under db/migrate, change the migration file with the name ending in add_admin_flag_to_users so that it looks like Example 14-4.
Example 14-4. A migration for adding a boolean administration flag to the users table
class AddAdminFlagToUsers < ActiveRecord::Migration def self.up add_column :users, :admin, :boolean, :default => false, :null => false end def self.down remove_column :users, :admin end end
This adds one column to the
users table, a boolean named
admin. It defaults to
false—most users will not be
administrators—and can’t have a null value. Run
rake db:migrate to run the migration and add
Next, there’s a small challenge. The system really should have at least one administrator, but building a complete user administration facility means building another whole set of forms and controller methods. In addition, it probably makes sense to be able to designate an initial user as administrator before locking all nonadministrators out of the user management system.
For this demonstration, there’s an easy answer—the Rails console. In addition to its use in ...