CODEWITHSUNDEEP
ruby-on-rails
port5432
port5432

Reputation: 6371

cloning a model in Rails

I have a model in Rails that I would like to use as a basis for another.

For example model: parent will be the template for model child. I can see two possible options:

(1) Inherit from the first model and then add additional columns

Class Parent < ActiveRecord::Base
Class Child < Parent

(2) Copy the model.rb file and add new features

Class Child < ActiveRecord::Base

In both cases the "Rails" part of the model is created, but what about the database table? I could create the table using create table child as select * from parent where 1=2 and then create migrations to add the additional columns, but it doesn't seem like the "Rails way".

Is there an easy way to create a migration based on an existing table. or am I barking up the wrong tree entirely?

Upvotes: 0

Views: 63

Answers (1)

Mischa
Mischa

Reputation: 43298

Your (1) is called single table inheritance (STI). Basically you use one table that has both the fields of the parent and the child. You'll also need a column called type to identify the type of the object.

Without more details I can't say if it's a good idea to use STI in your case, but (2) copying model.rb certainly doesn't seem right.

Upvotes: 2

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