Is there an elegant way to map column names.

rubyonrails-talk
1

I have been searching high and low but I can't find an elegant way to map database column names to model names.

The idea is simple if I have a column named 'CUSTOM_5' I want this to show up as "favorite_pet'.

So far all the suggestions I have seen are to create your custom methods which is fine but a lot of work if you have to map most if not all your fields.

Also creating getters and setters means you now have to add those methods to the to_xml and to_json methods as well as excluding the original field names.

Surely there is an easier way to handle this very common problem.

2

Could ruby's 'alias' command work for this? Something like:

  alias favorite_pet custom_5   alias favorite_pet= custom_5=

Not sure where you'd put those lines though...

3

That's not gonna work because those methods don't really exist. You could probably extend AR::Base's method_missing method, but really, you should change the database columns' names.

4

This should work.

Usage:

class GreenPastures < ActiveRecord::Base

alias_column “new_name” => “old_nAmE”

end

Include this code in a file in /lib

module Legacy def self.append_features(base)

super
base.extend(ClassMethods)

end module ClassMethods def alias_column(options) options.each do |new_name, old_name| self.send(:define_method, new_name) { self.send(old_name) }

    self.send(:define_method, "#{new_name}=") { |value| self.send("#{old_name}=", value) }
  end
end

end end

ActiveRecord::Base.class_eval do include Legacy end

5

class GreenPastures < ActiveRecord::Base

   alias_column "new_name" => "old_nAmE"

end

I saw this during my search. I am wondering how this is different that simply using the ruby alias command.

Of course this won't effect the "to_xml" and "to_json" methods. They seem to ignore the local attr.

I guess you'd have to build a hash, call this method for every member of the hash and finally pass those to the to_xml method.