CODEWITHSUNDEEP
ruby-on-railsactiverecordassociations
truthSeekr
truthSeekr

Reputation: 1633

rails associations - How would you represent this relationship?

I am trying to figure out a best way to represent the following relationship.

Newspaper has_many Articles
Newspaper has_many Subscribers

Subscribers are allowed to save the articles for their personal page.

Two Questions:

1) How would the relationship look like in rails? How would the action 'save' look like?

The following using has_many does not seem right to me:

class ArticleController < ApplicationController
  def save
    a = Article.find(101)
    @user.saved_articles << a
  end
end

2) Do I need a join table Saved_Articles that looked like this?

Saved_Articles
----------------
user_id, article_id

Upvotes: 1

Views: 77

Answers (3)

RubyFanatic
RubyFanatic

Reputation: 2281

Answer for Question #2: You don't need a join table for this. Just 3 separate tables (newspapers, articles, and subscribers) would be fine. The foreign keys for newspaper_id would be in articles and subscribers.

Upvotes: 1

RubyFanatic
RubyFanatic

Reputation: 2281

Answer QUestion #1:

in models/newspaper.rb: has_many :articles has_many :subscribers

in controllers/newspapers_controller.rb

def create
  @newspaper = NewsPaper.new(params[:newspaper])
  if @newspaper.save
    redirect_to 
  else
    render :new
  end
end

Upvotes: 1

dnch
dnch

Reputation: 9605

What you're describing is a many-to-many relationship. In terms of Rails associations, this is one way of defining it:

class Newspaper
  has_many :articles
  has_many :subscribers
end

class Subscriber
  belongs_to :newspaper
  has_and_belongs_to_many :articles
end

class Article
  belongs_to :newspaper
  has_and_belongs_to_many :subscribers
end

By using has_and_belongs_to_many, you will need a join table, but it would need to be called articles_subscribers and would have subscriber_id and article_id fields:

articles_subscribers
--------------------
article_id
subscriber_id

Your save action would then look something like the following, assuming @user was an instance of Subscriber:

class ArticlesController < ApplicationController
  def save
    @user.articles << Article.find(params[:id])

    # handle the response - render or redirect
  end
end

See http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html#method-i-has_and_belongs_to_many for more information on has_and_belongs_to_many

Upvotes: 3

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