Rails 4 view rendering extra object in view? - ruby-on-rails

Question

I have comments as a subresource of articles, as below:
resources :articles do
resources :comments
end
I want each Article's show page to display all of its corresponding comments, as well as have a form where a user (if signed in) can create a new comment that corresponds with the article.
Here's the show action for ArticlesController:
def show
#comment = #article.comments.build
if user_signed_in?
#comment.user_id = current_user.id
end
respond_with(#article)
end
Here's relevant code from the CommentsController:
before_action :set_article
...
def create
#comment = #article.comments.create(comment_params)
#comment.user_id = current_user.id
if #comment.save
flash[:notice] = "Comment successfully created!"
end
redirect_to #article
end
...
private
def set_article
#article = Article.find(params[:article_id])
end
end
And here's the Article show view:
<b>Post comments:</b><br />
<table>
<thead>
<tr>
<th>User email</th>
<th>Comment</th>
</tr>
</thead>
<tbody>
<% #article.comments.each do |comment| %>
<tr>
<td><%= comment.user.email %></td>
<td><%= comment.body %></td>
</tr>
<% end %>
</tbody>
</table>
<br />
<%= form_for ([#article, #comment]) do |f| %>
<div class="field">
<%= f.text_area :body, placeholder: "Compose new comment..." %>
</div>
<%= f.submit "Post" %>
<% end %>
Here's the two situations I need to fix:
When no user is signed in, the view fails to render because comment.user returns nil
When a user is signed in, a phantom comment for each article appears, because the show action in the ArticlesController is building a new (empty) comment with #comment = #article.comments.build
What is the best way to simultaneously solve both of these problems?

Answer 1

If you don't want to do that in the view, you can do this sort of thing in the controller.
def show
#comment = Comment.new(:article => #article)
respond_with(#article)
end
This won't add the comment to the article.comments array and won't try to render a blank comment.
Do you need to set the user_id on the comment in the form on the show action? If not, you can do this in create
def create
#comment = Comment.new(comment_params)
#comment.article = #article
#comment.user = current_user
if #comment.save
flash[:notice] = "Comment successfully created!"
redirect_to #article
else
render :show
end
end
The benefit to this - you can now handle errors in the form (like if they submit a blank comment, or minimum characters). Even if you handle it in the view with javascript/disabled buttons, it's nice to have the server also support validations and errors.

Answer 2

Just kidding, got it.
Put the build call into the form rather than the ArticleController:
<%= form_for ([#article, #article.comments.build]) do |f| %>
<div class="field">
<%= f.text_area :body, placeholder: "Compose new comment..." %>
</div>
<%= f.submit "Post" %>
<% end %>
and delete everything out of the show action:
def show
respond_with(#article)
end