How to assign a has_many/belongs_to relation properly in Rails ActiveRecord?

Question

I have a rails app with articles and author model. If I have an author and a post and want to indicate that the author should be the owner of the article, or that the articl

Answer 1

IMHO, the correct way of doing that is creating a instance method on your Article class, like the following:

class Author < ActiveRecord::Base
  ...
  def add_an_article(article)
    unless self.articles.include?(article)
      self.articles << article
    end
  end

end

This will provide a better semantic to your model and encapsulate the logic of the association manipulation...

That way, your class also will be compliant to Tell-don't-ask principle: http://pragprog.com/articles/tell-dont-ask.

Unfortunately, most of the Rails community ignores good OO principles and prefer the easiest but not right way of doing something!

Answer 2

There is not difference between the 3 following:

my_article.author_id = author_one.id
my_article.save
# same as
my_article.author = author_one
my_article.save
# same as
author_one.articles << my_article

To set the owner of a particular post, the most common and readable way would be:

post.author = author
post.save

OR shorter version:

post.update_attributes(author_id: author.id) # call an implicit save

Answer 3

I'm assuming you mean author_one.articles << my_article rather than just author_one << my_article

One difference between the two is that

author_one.articles << my_article

will save the change to the database immediately. i.e. it will either create the record for my_article if it has not been saved before or it will update the existing record to have author_id = author_one.id

whereas

my_article.author = author_one

or

my_article.author_id = author_one.id

will not be persisted until you do a my_article.save

Answer 4

Best thing is to use:

has_and_belongs_to_many

Because, author may have written many article and article can have many authors.