Rails - NoMethodError in Events#show undefined method `>' for nil:NilClass - ruby-on-rails

Question

I'm building an Events app in Rails and getting this error which seems a little odd.
It relates to the comments section at the foot of the show page. I'm simply attempting to move my comments form to the top of the section and have all recent comments below the form. This is my view code for the show page which results in the error code above -
<div id="comments">
<h3>Add a comment:</h3>
<%= render "comments/form" %>
<h2><%= #event.comments.count %></h2>
<%= render #event.comments %>
</div>
The reason I say its odd is that when I present the code like this (so the comments all show above the comment form) -
<div id="comments">
<h2><%= #event.comments.count %></h2>
<%= render #event.comments %>
<h3>Add a comment:</h3>
<%= render "comments/form" %>
</div>
I don't get the error code. Why would this be?
This is the code in my comments.html -
<div class="comment clearfix">
<div class="comment_content">
<p class="comment_name"><strong><%= comment.name %></strong></p>
<p class="comment_body"><%= comment.body %></p>
<p class="comment_time"><%= time_ago_in_words(comment.created_at) %> Ago</p>
</div>
<% if user_signed_in? %>
<p><%= link_to 'Delete', [comment.event, comment],
method: :delete,
class: "button",
data: { confirm: 'Are you sure?' } %></p>
<% end %>
The error refers to my events show action - I don't have any methods in my show action.

Answer 1

First make sure you have a nested route to create comments and an un-nested route to destroy them:
resources :events do
resources :comments, shallow: true, only: [:create, :destroy]
end
This is called shallow nesting and is desirable since it lets you route directly to resource for the member actions (show, edit, update, destroy) where a resource can be directly accessed through its unique id.
Then setup the form partial:
# comments/_form.html.erb
<%= form_for([commentable, Comment.new ]) do |f| %>
# ...
<% end %>
You then want to fix your events/show controller and view:
def show
#event = Event.eager_load(:comments).find(params[:id])
end
Note that we are not building a comment instance in the controller. We will do it later in the form when needed.
<div id="comments">
<% if #event.comments.any? %>
<h2><%= #event.comments.size %></h2>
<%= render #event.comments %>
<% else %>
<h2>There are no comments yet</h2>
<% end %>
<%= render 'comments/form', commentable: #event %>
</div>
Another big problem is that any signed in user can delete any comment. You can fix that by setting up an association:
class Comment < ApplicationRecord
belongs_to :user
end
class User < ApplicationRecord
has_many :comments
end
You then want to check that the user owns the comment:
<div class="comment clearfix">
<div class="comment_content">
<p class="comment_name"><strong><%= comment.name %></strong></p>
<p class="comment_body"><%= comment.body %></p>
<p class="comment_time"><%= time_ago_in_words(comment.created_at) %> Ago</p>
</div>
<% if user_signed_in? && comment.user == current_user %>
<% button_to 'Delete', comment,
method: :delete,
class: "button",
data: { confirm: 'Are you sure?' }
%>
<% end %>
</div>
Since we de-nested the destroy route you don't need to pass the event id as a param. Normally you want to use a library like Pundit or CanCanCan rather than spreading the authorization logic all over your application like this.
Added
For the delete button to work you need to associate the user with the comment:
def create
#event = Event.find(params[:event_id])
#comment = #event.comments.new(event_params) do |c|
c.user = current_user
end
# ...
end