Question

I am trying to write my delete method in my comment controller. My comment model has polymorphic associations with other models but in this case, we’ll just focus on trips. In other words, @trip = @commentable.

The comment gets deleted just fine, but I keep getting the error ActionController::ActionControllerError in CommentsController#destroy: Cannot redirect to nil! when I redirect_to @commentable which would be the trip that the comment belonged to.

I also redirected to @commentable in my create action (comment controller) and that works just fine when the user creates a new comment.

Any tips?

view (trips/show.html.erb)

<% if !@commentable.comments.empty? %>
  <% @commentable.comments.each do |comment| %>
    <!-- Content -->
    <%= link_to comment, :method => :delete do %> delete <% end %>
  <% end %> 
<% end %>

comment form that works for create action

<%= form_for [@commentable, Comment.new] do |f| %>
  <%= f.text_area :content %>
  <div id="comment_submit_button"><%= f.submit "Comment" %></div>
<% end %>

trips_controller.rb

def show
  @trip = @commentable = Trip.find(params[:id])
  @comments = Comment.all
end

comments_controller.rb

 def create
   @commentable = find_commentable
   @comment = @commentable.comments.build(params[:comment])
   @comment.user_id = current_user.id

   if @comment.save
     redirect_to @commentable
   end
 end

 def destroy
  # @commentable = find_commentable    this line was wrong
   @comment = Comment.find(params[:id]) 
   @commentable = @comment.commentable #this line fixed it
   if @comment.destroy
     redirect_to @commentable
   end
 end


def find_commentable
  params.each do |name, value|
    if name =~ /(.+)_id$/
      return $1.classify.constantize.find(value)
    end
  end
 nil
end

Answer 1

Figured out the solution. Will post solution in code above.

def destroy
  @comment = Comment.find(params[:id])
  @commentable = @comment.commentable
  if @comment.destroy
    redirect_to @commentable
  end
end