Rails: validation on blog comments not working - ruby-on-rails

Question

I am trying to learn Rails by building a simple blog. I have made it possible to add comments with AJAX en I am now trying to validate the presence of a name and body in the comments. However, the validation is not working. When there are no errors the comment gets added like it should, but when I leave either 'name' or 'body' blank and try to add the comment, I get redirected to this weird flat HTML-version of the post I was trying to comment on (with a path like this: /posts/21/comments). I do not understand why this is happening instead of just the post page reappearing with an error message in it, and I would be very grateful to anyone that could help me out.
So here is the CommentsController:
class CommentsController < ApplicationController
def create
#post = Post.find(params[:post_id])
#comment = #post.comments.create(comment_params)
if #comment.errors.any?
respond_to do |format|
format.html { render #post }
format.js
end
else
respond_to do |format|
format.html { redirect_to #post }
format.js
end
end
end
def destroy
#post = Post.find(params[:post_id])
#comment = Comment.find(params[:id])
#comment.destroy
respond_to do |format|
format.html { redirect_to #post }
format.js
end
end
private
def comment_params
params.require(:comment).permit(:name, :body)
end
end
Model:
class Comment < ActiveRecord::Base
belongs_to :post
validates_presence_of :body, :name
end
And comment part of show.html.erb:
<section id="comment-section">
<div id="comments">
<h2>Reacties</h2>
<%= render partial: #post.comments.reverse %>
</div>
<%= form_for [#post, Comment.new], remote: true, authenticity_token: true do |f| %>
<% if #comment && #comment.errors.any? %>
<% #comment.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
<% end %>
<p>
<%= f.label :name, "Naam" %><br/>
<%= f.text_field :name %></br></br>
<%= f.label :body, "Reactie" %><br/>
<%= f.text_area :body %>
</p>
<p><%= f.submit "Verstuur" %></p>
<% end %>
</section>
And the _comment.html.erb partial:
<%= div_for comment do %>
<p>
<strong>
Posted <%= time_ago_in_words(comment.created_at) %> ago
</strong>
<br/>
<i><%= comment.name %>:</i>
<%= comment.body %>
</p>
<p>
<% if logged_in? %>
<%= button_to 'Delete', [comment.post, comment],
:method => :delete,
:class=> 'link-button',
remote: true,
data: { confirm: 'Are you sure?' }
%>
<% end %>
</p>
<% end %>
Finally, my routes.rb file:
Rails.application.routes.draw do
get 'static_pages/aboutme'
get 'static_pages/photos'
get 'sessions/new'
resources :posts do
resources :comments, only: [:create, :destroy]
end
get 'admin' => 'sessions#new'
post 'admin' => 'sessions#create'
delete 'logout' => 'sessions#destroy'
get '/overmij' => 'static_pages#aboutme'
get '/fotos' => 'static_pages#photos'
root 'posts#index'
end

Answer 1

The error is on this line format.html { render #post } That line renders the comments.index as they are nested with in posts so you get post/:id/comments. If you want to render a view (from another controller) you have to do it like this:
render template "posts/show"
or just
render "posts/show"
But the thing about rendering a view/template is that it will not set any variables needed, so you'll get a error like #variable is nil so you need to set the variables needed for post/show. Another thing you can do is redirect_to #post but the thing about redirect is that it will refresh the page and erase what the user had typed in the text box.
These are rails docs on rendering/redirecting

Answer 2

Usually I use flash to display my error messages, something like this should work
Controller
respond_to do |format|
format.html { flash[:notice] = #comment.errors, render #post }
format.js
end
View
<%if notice.present? %>
<div class="alert alert-danger" role="alert">
<% notice.each do |msg| %>
<li><%= msg %></li>
<% end %>
</div>
<% end %>