Edit page not rendered properly - ruby-on-rails

Question

I'm very new to RoR. I'm trying to learn.
This is my user_controller update/edit part.
def edit
binding.break
#user = User.find(params[:id])
end
def update
#user = User.find(params[:id])
#binding.break
if #user.update(params.require(:user).keep_if{|key| #user.attributes[key] != params[:user][key]}.permit(:username, :email, :password))
# Call to debugger
flash[:notice] = "Article was updated successfully."
redirect_to #user
else
#binding.break
flash[:notice] = "Article was not updated successfully."
render 'edit'
end
end
This is my edit.html.erb file
<h1>Edit an existing User</h1>
<% if #user.errors.any? %>
<h2>The following errors prevented the user from being saved</h2>
<ul>
<% #user.errors.full_messages.each do |msg| %>
<%= puts msg%>
<li><%= msg %></li>
<% end %>
</ul>
<% end %>
<%= form_with(model: #user, local: true) do |f| %>
<p>
<%= f.label :username %><br/>
<%= f.text_field :username %>
</p>
<p>
<%= f.label :email %><br/>
<%= f.text_field :email %>
</p>
<p>
<p>
<%= f.label :password %><br/>
<%= f.password_field :password %>
</p>
<p>
<%= f.submit %>
</p>
<% end %>
The success case is working fine.
For the negative case where the update fails, I wanted to print the error messages for which the update failed and render it. But currently it just renders the edit page again. Also the #user in the else part of the controller is having the values which is invalid and those are getting filled in the edit page upon rendering. I want to reset to original values and show the errors for which it got failed.
The errors can be anything like, email format not correct or something.
Server logs says
↳ app/controllers/users_controller.rb:19:in `update'
TRANSACTION (0.2ms) rollback transaction
↳ app/controllers/users_controller.rb:19:in `update'
Rendering layout layouts/application.html.erb
Rendering users/edit.html.erb within layouts/application
Username has already been taken
Rendered users/edit.html.erb within layouts/application (Duration: 23.0ms | Allocations: 2337)
Rendered layout layouts/application.html.erb (Duration: 59.2ms | Allocations: 4962)
Completed 200 OK in 152ms (Views: 87.9ms | ActiveRecord: 5.0ms | Allocations: 11120)
Can someone shed some light on this?

Answer 1

render 'edit' with render edit without controller, you need to call #user = User.find(params[:id]) before render to get original value.
If you want to show errors message, grant it to other const and render it in views
def edit
binding.break
#user = User.find(params[:id])
end
def update
#user = User.find(params[:id])
#binding.break
if #user.update(params.require(:user).keep_if{|key| #user.attributes[key] != params[:user][key]}.permit(:username, :email, :password))
# Call to debugger
flash[:notice] = "Article was updated successfully."
redirect_to #user
else
#binding.break
#errors = #user.errors
#user = User.find(params[:id])
flash[:notice] = "Article was not updated successfully."
render 'edit'
end
end
in view, using #errors.full_messages