Question

I finished Hartl’s tutorial and have been trying to add twitter-like @replies for the past few days to no avail. I added an in_reply_to column to the Microposts table as an integer that I thought could be used to reference a given user’s id. As of now I’m using a regex to search for a match with a given user’s name via the Microposts controller.

Hartl suggests using an including_replies scope in the Micropost model. I’ll admit I’m not quite sure what to include in this scope based on what automatic associations rails creates or what I have to tell it.

Any assistance would be greatly appreciated.

User Model

  has_many :microposts, dependent: :destroy
  has_many :replies, through: :microposts, source: :in_reply_to

  VALID_NAME_REGEX =  /\A[\w+\-.]\z/i
  validates :name, presence: true,
            format: { with: VALID_NAME_REGEX },
            length: { maximum: 20 },
            uniqueness: { case_sensitive: false }

...

  def feed
    Micropost.from_users_followed_by(self)
    Micropost.including_replies
  end

Micropost Model

class Micropost < ActiveRecord::Base
  attr_accessible :content
  belongs_to :user
  belongs_to :in_reply_to, class_name: "User"

  validates :user_id, presence: true
  validates :content, presence: true, length: { maximum: 140 }

  default_scope order: 'microposts.created_at DESC'
  scope :including_replies, where("user_id = in_reply_to")

  def self.from_users_followed_by(user)
    followed_user_ids = "SELECT followed_id FROM relationships
                         WHERE follower_id = :user_id"
    where("user_id IN (#{followed_user_ids}) OR user_id = :user_id",
          user_id: user.id)
  end
end

Microposts Controller

class MicropostsController < ApplicationController
  before_filter :signed_in_user, only: [:create, :destroy]
  before_filter :correct_user,   only: :destroy
  before_filter :reply_to_user, only: :create

  def create
    @micropost = current_user.microposts.build(params[:micropost])
      if @micropost.save
      flash[:success] = "Micropost created!"
      redirect_to root_path
    else
      @feed_items = []
      render 'static_pages/home'
    end
  end

  def destroy
    @micropost.destroy
    redirect_to root_path
  end

  private

    def correct_user
      @micropost = current_user.microposts.find_by_id(params[:id])
      redirect_to root_path if @micropost.nil?
    end

    def reply_to_user
      if reply_to = @micropost.content.match(/\A(@[\w+\-.])\z/i)
      @other_user = User.where(name: reply_to.to_s[1..-1])
        if @other_user && current_user.followed_users.includes(@other_user)
        @micropost.in_reply_to = @other_user.id
        end
      end
    end

end

Answer 1

I’ve started to look into this and the first thing I’ve noticed is that your regexp looking for replies doesn’t work:

> /\A(@[\w+\-.])\z/i.match("@someName blabla")
=> nil 

So the first tip: test every bit you’re implementing.
Also, I think you got the association wrong, I used

   has_many :replies, foreign_key: "to_id", class_name: "Micropost"

(I’ve renamed the key from in_reply_to to simply “to” because there was a strange deprecation warning when using the underscores).

but you mainly asked how to define the new scope in Micropost. I did it like this:

scope :from_users_followed_by_including_replies, lambda { |user| followed_by_including_replies(user) }

…

def self.followed_by_including_replies(user)
  followed_ids = %(SELECT followed_id FROM relationships
                   WHERE follower_id = :user_id)
  where("user_id IN (#{followed_ids}) OR user_id = :user_id OR to_id = :user_id",
        { :user_id => user })
 end

I hope that helps. you can have a look at my whole implementation at

https://github.com/htw-rails/TutorialSampleApp32/tree/reply