Default value for non-ActiveRecord models

[abacha]

I'm using as_enum on a non-activerecord class by including it is it possible to set a default value on an enum?

[lwe]

Actually rather than using ruby to handle that, I'd either set it A) in the initializer or B) in the reader of the _cd value. Hope one of these solutions works for you?

class Message
  extend SimpleEnum::Attribute
  attr_accessor :status_cd
  as_enum :status, %w{unread archived trashed}

 # A) in the initializer...
 def initializer
   @status_cd = 0 # == :unread
 end

  # ...or B) ensure status_cd has a value when set to nil
  def status_cd
    @status_cd ||= 0 # == :unread
  end
end

[abacha]

yeah, I was using like this but I find it to obscure why can't we have the same syntax as the mongoid enum? as_enum :gender, [:male, :female], field: { :type => Integer, :default => 1 }

[lwe]

Could you write a SimpleEnum::Convenience similar to https://github.com/lwe/simple_enum/blob/master/lib/simple_enum/mongoid.rb which basically does

      def as_enum(name, values, options = {})
        source = options[:source].to_s.presence || "#{name}#{SimpleEnum.suffix}"
        field_options = options.delete(:field) || {}
        unless field_options === false
          attr_accessor source
          define_method(source) do
            return field_options[:default] unless instance_variable_defined?("@#{source}")
            instance_variable_get("@#{source}")
          end
        end

        super
      end

^^ not sure if it works at all, was just an idea, that we can have use include SimpleEnum::Convenience similar to SimpleEnum::Mongoid which creates the attribute, handles the default etc, what do you think? Also I'm not happy with the name Convenience, maybe you have a better idea :smile:

Update: how about SimpleEnum::Model as it adds some "model" support by creating fields and stuff?

[Startouf]

The whole point of enums is to be meaningful. I'd rather be able to set default values like this

as_enum :status, [:ok, :maintenance_needed, :broken], default: :ok

...rather than having to specify a default integer value that means nothing.

[lucke84]

@Startouf +1

[lwe]

All right, it looks like a few people are interested in this feature. Following considerations:

• A) This only makes sense for non ActiveRecord models, as AR models should set the default value via Rails migration / in the DB schema and thus I do not think it makes sense to allow this for AR models
• B) Really like the proposal from @Startouf to allow setting it as enum value, which indeed would make sense
• C) This feature would then require to be implemented for MongoId and with Plain-Old-Ruby-Objects, any proposals?

[Startouf]

• A) Yeah I guess you're right. I'm so glad I switched to Mongoid, I just can't stand migrations...
• B) Cool
• C) Is there going to be much difference between the Mongoid implementation and the Ruby object one ? do we want to change the association_cd value in the database after the field is created, or do we want the accessor to return the default value instead of nil ?

Anyway, you'll need to consider adding a :default key to your options param hash starting from attribute.rb. Also, it wouldn't hurt to raise an exception of let the programmer/user know if the provided default value isn't in the enum hash.

[lwe]

To keep it simple I think both Ruby objects and Mongoid should use the same logic. For functionality like this my accessor model seems to start to break, as there's a single class handling reading, writing etc., so it's hard to have different behavior. Maybe it should be refactored to a reader / writer component and then the reader can be a DefaultValueReader or something like that...