From: Paolo Negri <hungrylist@...>
Date: 2006-09-05T21:04:02+09:00
Subject: Re: Enum

Hi

adding some informations to your hash may help, something like..

{ :hidden => {:id => 1, :label => 'Hidden'}, :available => {:id => 2,
:label => 'Available'},  :in_progress => {:id => 3,  :label => 'In
progress'}, :complete => {:id => 4, :label => 'Complete' }}

gives you an index to trust

and next you can do something like

(note, the code isn't checked so probably won't work as it is)

statuses.each do |key, value|
  define_method(key.to_s + '?') {
    self.status == value[:id]
  }
end

to have all the hidden? available? etc. methods.

Anyway I think that if you have a look to the rails humanize method
you could avoid the label field so you can manage the statuses with a
simple hash or even an array.

Paolo

On 05/09/06, Ohad Lutzky <lutzky@gmail.com> wrote:
> I want an enum of sorts in my Rails application.
>
> I have a Project object, which has four possible status settings, as
> indicated here:
>
>   class Project < ActiveRecord:Base
>     ...
>     class << self
>       def statuses
>         [ 'Hidden', 'Available', 'In progress', 'Complete' ]
>       end
>     end
>     ...
>   end
>
> These are not expected to change, so hardcoding is preferable. Of
> course, there is a 'status' column in the project table, so rails
> creates a 'status' accessor.
>
> However, later in the code I will want to check the status myself. For
> example, 'Complete' projects won't be shown in the same place as
> 'Available' ones, and 'In progress' and 'Hidden' projects won't be shown
> at all (not sure about In progress ATM though, so I want to keep it
> flexible). Now, it would be pretty ugly checking
>
>   if a_project.status == 2 # Project is in progress
>
> So one possibility is to add methods like
>
>   class Project
>     def in_progress?
>       self.status == 2
>     end
>   end
>
> Another interesting option is this:
>
>   class Project
>     def status_is?(_status)
>       [ :hidden, :available, :in_progress, :complete ][self.status] ==
> _status
>     end
>   end
>
> If only I could count on hashes staying in order, a very pretty solution
> would
> be:
>
>   class Project
>     class << self
>       def statuses
>         { :hidden => 'Hidden', :available => 'Available',
>           :in_progress => 'In progress', :complete => 'Complete' }
>         # Use Project.statuses.values for the dropdown
>       end
>     end
>     def status_is?(_status)
>       Project.statuses.keys[self.status] == _status
>     end
>   end
>
> Unfortunately, "The order in which you traverse a hash by either key or
> value may seem arbitrary, and will generally not be in the insertion
> order." (ri).
>
> Any other ideas for elegance?
>
>
> --
> Posted via http://www.ruby-forum.com/.
>
>