binding.pry

From: /home/ubuntu/workspace/app/views/topics/show.html.erb @ line 30 ActionView::CompiledTemplates#_app_views_topics_show_html_erb___4440374457857120152_70213913638600:

    25: </ul>
    26: 
    27: <br>
    28: 
    29: <ul class="attributes">
 => 30:   <% binding.pry %>
    31:   <% if @topic.comments.any? %>
    32:     <%= @topic.comments.each do |comment| %>
    33:       <%= comment.author.email %>
    34:       <%= comment.text %>
    35:     <% end %>

[1] pry(#<#<Class:0x007fb7e5ece678>>)> @topic
=> #<Topic:0x007fb7e64d01c0
 id: 4,
 title: "Sonic has a new charbroiled burger",
 description: "Has anyone tried it yet? I hear it's supposed to taste really good.",
 forum_id: 1,
 created_at: Thu, 19 May 2016 00:46:33 UTC +00:00,
 updated_at: Thu, 19 May 2016 00:46:33 UTC +00:00,
 author_id: 1>
[2] pry(#<#<Class:0x007fb7e5ece678>>)> @topic.comments.count
   (0.5ms)  SELECT COUNT(*) FROM "comments" WHERE "comments"."topic_id" = ?  [["topic_id", 4]]
=> 1
[3] pry(#<#<Class:0x007fb7e5ece678>>)> @topic.comments
  Comment Load (0.2ms)  SELECT "comments".* FROM "comments" WHERE "comments"."topic_id" = ?  [["topic_id", 4]]
=> [#<Comment:0x007fb7e5dfff30
  id: 4,
  topic_id: 4,
  text: "Alright this is a comment created through the form.",
  created_at: Tue, 31 May 2016 00:11:04 UTC +00:00,
  updated_at: Tue, 31 May 2016 00:11:04 UTC +00:00,
  author_id: 2>,
 #<Comment:0x007fb7e6c720b8 id: nil, topic_id: 4, text: nil, created_at: nil, updated_at: nil, author_id: nil>]
[4] pry(#<#<Class:0x007fb7e5ece678>>)> 

Comment Model

class Comment < ActiveRecord::Base
  belongs_to :topic
  belongs_to :author, class_name: "User"
  validates :text, presence: true, length: { minimum: 15 }
end

Corresponding Migration

class AddAuthorToComments < ActiveRecord::Migration
  def change
    add_reference :comments, :author, index: true
    add_foreign_key :comments, :users, column: :author_id
  end
end

Topic Controller

class TopicsController < ApplicationController
  before_action :set_forum
  before_action :set_topic, only: [:update, :destroy, :edit, :show]
  before_action :verify_author, only: [:destroy, :update, :edit]
  before_action :authenticate_user!, only: [:create, :new]

  def index
    @topics = Topic.all
  end
  
  def new
    @topic = @forum.topics.build
  end
  
  def show
    @comment = @topic.comments.build
  end
  
  def edit
  end
  
  def create
    @topic = @forum.topics.build(topic_params)
    
    @topic.author = current_user
    
    if @topic.save
      flash[:notice] = "Topic has been successfully created."
      redirect_to [@forum, @topic]
    else
      flash.now[:alert] = "Topic has not been created."
      render 'edit'
    end
  end
  
  def destroy
    @topic.destroy
    
    flash[:notice] = "Topic has been deleted."
    redirect_to @forum
  end
  
  def update
    if @topic.update(topic_params)
      flash[:notice] = "Topic has been updated."
      redirect_to [@forum, @topic]
    else
      flash.now[:alert] = "Topic has not been updated."
      render 'edit'
    end
  end
  
  private
  
  def topic_params
    params.require(:topic).permit(:title, :description)
  end
  
  def set_forum
    @forum = Forum.find(params[:forum_id])
  end
  
  def set_topic
    @topic = @forum.topics.find(params[:id])
  end
  
  def verify_author
    unless current_user.email == @topic.author.email || current_user.admin?
      flash[:alert] = 'Only the author can edit or delete their own post.'
      redirect_to forums_path
    end
  end
end

Topic View - show.html.erb

<ul class="attributes">
  <% if @topic.comments.any? %>
    <% @topic.comments.each do |comment| %>
      <li><h4><%= comment.author.email %> -</li></h4>
      <li><%= comment.text %></li>
    <% end %>
  <% else %>
    <p>There are no comments on this topic (yet!)</p>
  <% end %>
</ul>

<header>New Comment</header>

<%= render 'comments/form' %>