Dynamicaly creating a model with a real DB as attribute of another model

Question

I have a table named "tables" and inside there is a column named table_name. And, on my DB inside other schema I have this table. Like:

db: tables
id  table_name  other_attributes
 1  minerals    ...
 2  animals     ...

db: minerals
id  name  type
 1  rock  nil
 2  sand  nil

The tables doesn't have the same structure. I would like to call my model like:

> tab = Table.find(1)
> tab.elements.all
=> [ {id: 1, name: 'rock', type: nil}, {id: 2, name: 'sand', type: nil} ]

And use any kind of active record tasks inside this .elements... I didn't find any way and the closest article that I found was this: Rails 3/ActiveRecord: How to switch/change table name during request dynamically?

Answer 1

I believe the best approach in your case it to perform a direct update to the database. If you don't like to write SQL directly, you can rely on some high-level libraries such as Sequel that in this case are a little bit less coupled to the conventions imposed by ActiveRecord.

Answer 2

If you are using PostgreSql you might be interested in hstore - http://railscasts.com/episodes/345-hstore. Using hstore (it stores json) would simplify very much your db and application :)

Answer 3

Some time after this question I think (just think because I dont know if it is really right) here is the answer:

class TableMaster < ActiverRecord::Base
  attr_accessor :db
  after_find do
    me = self
    me.db = Class.new ( ActiveRecord::Base ) do
        self.table_name = "schema." + me.tablename
    end
    true
  end
end

Just put it inside the model and there will be a full functional Active Record model inside another. I'm really happy that I got this answer but am still in doubt if it's really right. Please send me some sugestions of it.