从另一个类中调用一个类-Ruby on Rails

Question

I searched around the SOF and couldn't find a simple answer for my simple question.

I have two classes, Author and Book .

class Author < ActiveRecord::Base

    def greet
        puts "Hello, I'm #{name}."
    end

    def describe
        puts "That Author's name is #{name}.
        puts "This author wrote this book #{book}." #<--- I want to write this or combine it with the line above
    end

end

In class book, I don't have anything just

class Book < ActiveRecord::Base end

How can I puts the following: That Author's name is ... and This author wrote this ... when I enter Author.first.describe in the Rails console?

Answer 1

based on the information you gave me in the comment your relations would look something like this:

class Author < ActiveRecord::Base
    belongs_to :book
end

class Book < ActiveRecord::Base
    has_one :author
end

The describe method in your Author class could look something like

def describe
  "That Author's name is #{name}. This author wrote this book #{book.title}."
end

This is based on you stating you have the book_id in your authors table, and I am also assuming you have a title or name field in your books table.

However, it feels more natural to have the Author owning the book, and the book belonging to the Author, so might I suggest changing your data structure a bit to remove the book_id from authors table, and instead place an author_id in book table, and then your models relations would look like this:

class Author < ActiveRecord::Base
    has_one :book
end

class Book < ActiveRecord::Base
    belongs_to :author
end

Answer 2

class Author < ActiveRecord::Base
has_many :books

class Book < ActiveRecord::Base
belongs_to :author

and in the migration author:references

 class CreateServices < ActiveRecord::Migration[5.0]
  def change
    create_table :services do |t|
      t.string :title
      t.text :description
      t.text :require
      t.integer :price
      t.references :user, foreign_key: true

      t.timestamps
    end
  end
end

this is a project i'm working on, i'm using user but in your case is author.