How to share data between two models in Ruby on Rails

Question

Hi I am implementing a web app on RoR. My first model has got three fields as input (weight, height and gender) while my second model has got 2 fields (weight and height). I have implemented the first model and am thinking to create a separate model for the one with two fields. The task is that when I put data into second model (which i am thinking to implement), my code should extract all the data from the first model ie the one with three fields, and then I should perform calculations on it.

My question is:

Will the same db be shared between these two models? and how should i extract the data from the first model when I enter and submit the data into second model form?

Answer 1

From the details of your question it's not entirely certain, but perhaps Single Table Inheritance could help you here.

Basically you can have these models:

class BaseModel < ActiveRecord::Base; end
class ThreeFieldModel < BaseModel; end
class TwoFieldModel < BaseModel; end

Your migration would contain all fields including a magical type column:

create_table :base_model do |t|
  t.string :type,   null: false
  t.string :weight
  t.string :height
  t.string :gender
  t.timestamps
end

If you decide to use STI, I recommend to read one or two tutorials regarding this topic. Properly using STI with Rails can be difficult at times.