ruby script/plugin install svn://rubyforge.org/var/svn/enum-column

In your schema
==============
When you create your schema, specify the constraint as a limit:

  create_table :enumerations, :force => true do |t|
    t.column :severity, :enum, :limit => [:low, :medium, :high, :critical],
       :default => :medium
    t.column :color, :enum, :limit => [:red, :blue, :green, :yellow]
    ...
  end

In the model
===========
You can then automatically validate this column using:

    validates_columns :severity, :color

The rest will be handled for you. All enumerated values will be given as symbols.

    @e = Enumeration.new
    @e.severity = :low

In the views.
=============
In the controller:

   @e = Enumeration.new

The enumerates list of values will be specified as follows:

    <%= input 'e', 'severity' %>

Will create a select/option list:

     < select id="e_severity" name="e[severity]">
     	     < option value="low">low< /option>
	     < option value="medium" selected="selected">medium< /option>
	     < option value="high">high< /option>
	     < option value="critical">critical< /option>
     < /select>

You can also create a set of radio buttons using the following helper:

    <%= enum_radio('e', 'severity') %=>

Will produce the following group of radio buttons:

    < label>low: < input id="test_severity_low" name="test[severity]" type="radio" value="low" />< /label>
    < label>medium: < input checked="checked" id="test_severity_medium" name="test[severity]" type="radio" value="medium" />< /label>
    < label>high: < input id="test_severity_high" name="test[severity]" type="radio" value="high" />< /label>
    < label>critical: < input id="test_severity_critical" name="test[severity]" type="radio" value="critical" />< /label>

You can always use the column reflection to get the list of possible values from the database column.

    Enumeration.columns_hash['color'].values

Will yield: [:red, :blue, :green, :yellow]

There is currently no advanced documentation for this plugin.