From: Simen Edvardsen <toalett@...>
Date: 2006-06-23T04:11:01+09:00
Subject: Re: Turning an Array into a Hash based on an attribute value

$ irb
irb(main):001:0> class Array
irb(main):002:1>   def hash_on(method)
irb(main):003:2>
Hash[*self.map{|m|m.send(method).to_s.to_sym}.zip(self).flatten ]
irb(main):004:2>   end
irb(main):005:1> end
=> nil
irb(main):006:0> [1, "2", :three].hash_on(:class)
=> {:String=>"2", :Symbol=>:three, :Fixnum=>1}
irb(main):007:0>


On 6/22/06, Ashley Moran <work@ashleymoran.me.uk> wrote:
> A guy I work with has some some work on an ActiveRecord class that
> basically reads static lookup data, and contains (among other things)
> an "identifier" attribute.  Given an array of all these objects he
> wanted to access them by the contents of the identifier attribute, eg:
>
> data_items = DataItem.find(:all)
> # data_items[3].identifier => "my_identifier"
> data_items[:my_identifier].do_something # => data_items[3].do_something
>
> The best I can come up with is this:
>
>    class Array
>      def hash_on(method)
>        method = method.to_sym
>        hash = { }
>        self.each do |i|
>          hash[i.send(method).to_s.to_sym] = i
>        end
>        hash
>      end
>    end
>
>    > [1, "2", :three].hash_on(:class)
>    => {:String=>"2", :Symbol=>:three, :Fixnum=>1}
>
> Is there a neater (one-line?) way I missed?
>
> Ashley
>
>


-- 
- Simen