Rails - Sep 2006 - Can't dynamically create an Acitve::Record object

Can anyone explain why the following shows that when you dynamically 
create an Active::Record object, the accessors/mutators for the columns 
are not created? Very puzzled! Thanks :o)

            klass = Class.new(ActiveRecord::Base) do
              set_table_name table_name
            end
            Kernel.const_set(model_class_name, klass)

            puts "Created the model class and set as a constant."

            column_names = model_class.columns.map{ |x| x.name }
            methods = model_class_name.constantize.new.methods
            raise "Columns not in instance as methods\n\n"+
              
"Columns:\n\n#{column_names.sort.join("\n")}\n\n"+
               "Instance
Methods:\n\n#{methods.sort.join("\n")}"
               if methods & column_names != column_names

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On 9/19/06, Matthew Painter
<rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
>
>
> Can anyone explain why the following shows that when you dynamically
> create an Active::Record object, the accessors/mutators for the columns
> are not created? Very puzzled! Thanks :o)
>

I''m not sure what''s wrong with the code you listed, but
here''s a module I
use to create dynamic active record objects.


module Stone
  module Dynamic
    class << self
      def klass(table_name)
        tname = class_name_from_table(table_name)
        #see if it has already been defined
        const_missing(tname)
      rescue NameError
        define_klass(table_name)
      end

      def objeck(table_name)
        klass(table_name).new
      end

      private
        def class_name_from_table(table_name)
          Inflector.camelize(table_name)
        end

        def define_klass(table_name)
          tname = class_name_from_table(table_name)
          class_def = <<-end_eval
            class #{tname} < ActiveRecord::Base
              set_table_name(''#{table_name}'')
            end
          end_eval
          eval(class_def, TOPLEVEL_BINDING)
          const_get(tname)
        end
    end
  end
end


Hope this is of some use,
andy

-- 
Andrew Stone


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On 9/19/06, Matthew Painter
<rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
>
> Can anyone explain why the following shows that when you dynamically
> create an Active::Record object, the accessors/mutators for the columns
> are not created? Very puzzled! Thanks :o)

Try it with a ''normal'' AR object - doesn''t work
either. Attribute
getters/setters are handled by method_missing, which defines instance
methods at runtime for speed.

Otherwise, Object.const_set :Person, Class.new(ActiveRecord::Base) is
plenty.

jeremy


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Thanks guys!


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