Enumeration

The :enum field type is for when you need to display a list of potential values. It will be rendered with a select box in forms.

Other advantage, a filter with a select box will be added too.

As usual with RailsAdmin, there are two ways to do this.

Using the smart default approach

If you have a :color column in your Team model, RailsAdmin will check if Team#color_enum exists. If it does, then you're done.

The result call will be sent to FormOptionsHelper#options_for_select to fill the select box. See this for possible output (hash, array)

def Team < ActiveRecord::Base
  def color_enum
    # Do not select any value, or add any blank field. RailsAdmin will do it for you.
    ['green', 'white']
  end
end

Using the configuration approach

# you need to tell RailsAdmin that you want to use an `:enum` field
field :color, :enum do 
  # if your model has a method that sends back the options:
  enum_method do
    :my_color_enum_instance_method
  end

  # or doing it directly inline
  enum do
    # simple array
    ['green', 'white']
  end

  # if you need select the default value
  default_value 'green'

  enum do
    # ActiveRecord querys
    except = bindings[:view]._current_user.team_id
    Team.where('id != ?', except).map { |c| [ c.name, c.id ] }
  end
end

*** If you are using enumerator in has_one association field, be aware to place _id after field's name in RailsAdmin initializer, otherwise you can have problems.

field :responsible_id, :enum do
  enum do
    # ...
  end
end

# instead

field :responsible, :enum do
  enum do
    # ...
  end
end

Integration with enum plugins

• The Enumerize gem will automatically generate the appropriate _enum methods.

• The bitmask_attributes gem can be configured this way:

    configure :my_mask, :enum do
      enum_method do
        name
      end

      enum do
        Hash[abstract_model.model.bitmasks[name].map { |k,v| [k.humanize.titleize, v] }]
      end

      pretty_value do
        bindings[:object].send(name).map{|v| v.to_s.humanize.titleize }.join(', ')
      end

      def form_value
        bindings[:object].send(name)
      end

      # set this to true for multi-select
      multiple do
        false
      end
    end

Multi-select ENUM example using User.roles as example...

During Create/Update, display a Multi-Select Widget for :roles field. Stores/Retrieves the selected options as array into a single db string field as serialized array.

model/user.rb

class User < ActiveRecord::Base
    serialize :roles, Array
    def roles_enum
        [ [ 'role one', '1' ], [ 'role 2', '2' ], [ 'role 3', '3' ] ]
    end
    def has_role?( role )
        # example called from cancan's app/models/ability.rb
        # if user.has_role?( :ADMIN

        # for roles array stored in db... take each value, see if it matches the second column in the roles_enum array, if so, return the 1st col of the enum as a uprcase,space_to_underscore,symbol .
        assigned_roles = self.roles.map { |r| self.roles_enum.rassoc(r)[0].gsub(/ /, '_').upcase.to_sym }
        assigned_roles.include?( role )
    end
end

More here