[RAILS] How to get only articles and transactions that you commented or messaged [includes]

Introduction

Often on sites with flea market elements such as Mercari and Jimoty Apart from the list of transactions that I have listed on My Page The list of transactions in progress is often displayed, isn't it?

Bookmarking every transaction can be a hassle, so Isn't it a useful function?

Today I would like to implement it to make it happen.

Relationship between models

As in the example, the article (transaction) is an article and the comment (exchange) is a comment. Each model should be associated as above.

user.rb

  has_many :articles
  has_many :comments

article.rb

  belongs_to :user
  has_many :comments

comment.rb

  belongs_to :user
  belongs_to :article

Acquisition of articles (transactions)

application_controller.rb

  helper_method :current_user

  private
  
  def current_user
    if session[:user_id]
      @current_user ||= User.find_by(id: session[:user_id])
    end
  end

Assuming that there is a helper method current_user that returns the logged-in user as described above, Get the articles you commented on the following @article_commented_on.

home_controller.rb

  def mypage
    @article_commented_on = current_user.messages.includes(:article).map(&:article).uniq
  end

Get all the comments posted by the user with current_user.messages and Use includes (: article) to join a table with an article.

Then, use map (&: article) to return only the article to the extracted new array. Execute uniq (a method of an array that is not a method for querying) to eliminate duplicates.

By doing this, I was able to get only the articles that I had commented on in @article_commented_on.

By doing a table join with includes (: article) You can minimize the access to the DB that occurs every time you get the article corresponding to each message.

That's all, thank you for your hard work!