Rails errors not showing? - ruby-on-rails

Question

So im learning rails, and following the rails getting started guide (I've actually done the "blog app" on the Udemy rails course, but im making sure I can write it from scratch first before moving on).
Anyways, i've gotten Delete/Create running, but I was adding validation...and while the validation works my errors aren't showing up.
Right now my pages are super simple:
new.html.erb
<% if #user.errors.any? %>
<div id="error_explanation">
<h2>
<%= pluralize(#user.errors.count, "error") %> prohibited this user from being saved
</h2>
<ul>
<% #user.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<%= form_with scope: :user, url: users_path, local: true do |form| %>
<p>
<%= form.label :username %><br>
<%= form.text_field :username %>
</p>
<p>
<%= form.label :name %><br>
<%= form.text_field :name %>
</p>
<p>
<%= form.label :age %><br>
<%= form.number_field :age %>
</p>
<p><%= form.submit %></p>
<% end %>
users_controller
class UsersController < ApplicationController
def index
#users = User.all
end
def new
#user = User.new
end
def edit
#user = User.find(params[:id])
end
def create
#user = User.new(params.require(:user).permit(:username,:name,:age))
if #user.save
redirect_to users_path
else
render 'new'
end
end
def update
end
def destroy
#user = User.find(params[:id])
#user.destroy
redirect_to users_path
end
end
So the weird thing if I go into my network tab in dev tools I can see this show up in the response tab:
<div id="error_explanation">
<h2>
1 error prohibited this user from being saved
</h2>
<ul>
<li>Username has already been taken</li>
</ul>
</div>
But it doesn't show up in "elements" in Chrome dev tools. I've restarted rails....so Im really not sure why the elements are not showing up. I DO have bootstrap 4.00 beta installed, but not sure why that would matter. This is rails 5.1.4 btw.

Answer 1

This is because you are not getting the same #user in the <% if #user.errors.any? %>
Try this :
<%= form_with scope: :user, url: users_path, local: true do |form| %>
<% if #user.errors.any? %>
<div id="error_explanation">
<h2>
<%= pluralize(#user.errors.count, "error") %> prohibited this user from being saved
</h2>
<ul>
<% #user.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<p>
<%= form.label :username %><br>
<%= form.text_field :username %>
</p>
<p>
<%= form.label :name %><br>
<%= form.text_field :name %>
</p>
<p>
<%= form.label :age %><br>
<%= form.number_field :age %>
</p>
<p><%= form.submit %></p>
<% end %>