Question

I have this custom model, with some methods in it:

class GenericModel < ActiveRecord::Base 
  self.abstract_class = true

  def get_settings
   .....
  end
end

I want to inherit this GenericModel class in my various other Models like below, so that I can have access to those custom methods:

class ProvinceSetting < GenericModel 
end

class CitySetting < GenericModel 
end

But, how do I write my custom method so that it acts on a specific table in the database depending upon which Model class is calling it ? Any pointers would be welcome

Is this the correct implementation of get_settings in GenericModel, where self would refer to appropriate model name ?

def self.get_settings(user_id)
    user_session = SettingsSession.find_by_user_id(user_id)

    if !user_session.blank?
      if setting_orig = self.find_by_settings_session_id(user_session.id)
          setting = setting_orig.dup
      end

    else
      setting = self.first.dup
    end 

 return setting
end

Answer 1

If you want to call the table name used by the subclass, then you’re done – it will do that already:

class GenericModel < ActiveRecord::Base
  def get_settings
    all # this will get all settings for the subclass that calls it
  end
end

If you need to use some other table name, make a method in each subclass that defines the tablename, and call that method in the abstract base model:

class ProvinceSetting < GenericModel
  def special_table_name
    'foo'
  end
end

class CitySetting < GenericModel
  def special_table_name
    'bar'
  end
end

class GenericModel < ActiveRecord::Base
  def get_settings
    ... # use 'special_table_name' method in a query
  end
end