Render inline errors in Rails forms after submit

_form.html.erb

<%= form_with(model: post) do |form| %>
<% error_handler = ::InlineErrorHandler.new(post, self) %>
  <div>
    <%= form.label :title, style: "display: block" %>
    <%= form.text_field :title %>
    <%= error_handler.error_message_for(:title) %>
  </div>

  <div>
    <%= form.label :body, style: "display: block" %>
    <%= form.text_area :body %>
    <%= error_handler.error_message_for(:body) %>
  </div>

  <div>
    <%= form.submit %>
  </div>
<% end %>

inline_error_renderer.rb

class InlineErrorHandler
  def initialize(model, view_context)
    @model = model
    @view_context = view_context
  end

  def error_message_for(attribute)
    if errors[attribute].present?
      @view_context.content_tag(:span, errors[attribute].join(", "), class: "error")
    end
  end

  private

  attr_reader :model, :view_context

  def errors
    @errors ||= model.errors
  end
end

This is how it will be displayed after the form submit

With hotwire added, it stays on the same page customers/new and renders the errored state of the form.

Screen.Recording.2021-06-06.at.11.20.52.AM.mov

This code doesn't work. I got an error:
"cannot load such file -- I:/RB/proj/AskIt/app/controllers/InlineErrorRenderer.rb"

This code doesn't work. I got an error: "cannot load such file -- I:/RB/proj/AskIt/app/controllers/InlineErrorRenderer.rb"

@vasilevskykv class InlineErrorRenderer is meant to be a service class and not a controller. Add that file in a new folder inside app called as service and then create a file with the name inline_error_renderer.rb and then paste that code. It should work then.