Insert data into rails

Question

I am new to rails and don't know how to insert data into db.

I am reading CSV and want to load these values ​​in db. My model looks something like this.

class Book < ActiveRecord::Base
  belongs_to :subject
end

class Subject < ActiveRecord::Base
  has_many :books
end

... and my data is something like this:

Science, Book A
Science, Book B
History, Book C
Math, Book D

I am separating CSV lines with a delimiter.

How to insert data so that if an object exists, a child’s book entry will be added to the existing topic, but if the object does not exist, a new object will be created?

This is the best way to do this, or someone may recommend a better approach.

Answer 1

. csv, subjects.csv, : http://api.rubyonrails.org/classes/Fixtures.html

Answer 2

@idlefingers :

subject = Subject.find_or_create_by_name("Science")

subject.books.create(:name => "Book A")