Rails Devise sign up form undefined method `devise_error_messages!'

Question

i'm trying to use devise for handling user login/registration/forgotten password

I want to have sign up form at my root url root 'home#index'

HomeController

class HomeController < ApplicationController

    include DeviseHelper

    def index

    end

end

DeviceHelper

module DeviseHelper
    def resource_name
       :user
     end

     def resource_class 
        User 
     end

     def resource
       @resource ||= User.new
     end

     def devise_mapping
       @devise_mapping ||= Devise.mappings[:user]
     end

end

views/home/index.html.erb

  <%= form_for(resource, as: resource_name, url: registration_path(resource_name))  do |f| %>

<%= devise_error_messages! %>

<div class="field">
  <%= f.label :email %><br />
  <%= f.email_field :email, autofocus: true %>
</div>

<div class="field">
  <%= f.label :password %>
  <% if @minimum_password_length %>
  <em>(<%= @minimum_password_length %> characters minimum)</em>
  <% end %><br />
  <%= f.password_field :password, autocomplete: "off" %>
</div>

<div class="field">
  <%= f.label :password_confirmation %><br />
  <%= f.password_field :password_confirmation, autocomplete: "off" %>
</div>

<div class="actions">
  <%= f.submit "Sign up" %>
</div>

when I try to sign up with wrong attributes it shows me this error

undefined method `devise_error_messages!' for #<#:0x007fb430638300>

how can I fix this error. Also is using Devise module good practise?

Answer 1

The best option is to rename your own DeviseHelper to something else. Rails's autoloading is finding your implementation of DeviseHelper instead of Devise's, so the method is not being loaded. Call it something less specific, e.g. AuthHelper.

The advantage of this over pulling in your own implementation do devise_error_messages! is that you will automatically pick up changes to the method that Devise may make in future versions, as well as you'll have less code in your app, both making your code more sensible / maintainable.