Devise not displaying error messge during an authentication failure?

I was expecting a flash notice when authentication failures occurs in devise. But get nothing during a authentication failure, just the page refreshes and remains still. I didn't change any stuffs. The default devise installation itself is not displaying flash errors with invalid authentication attempt. I just installed devise as a gem a tryed to uise it. Din't even change a word of the co开发者_Go百科de that is generated.

May be I thought if is it due to some browser comparability issues.

But I get other mannually introduced flash messsages else working.

Any suggestions as to what may be broken.

I'm using rails 3.0.1

* Update *

I'm getting failure messages for user registration(sign up) but not for failures messages of signing in. some googleing on this topic revealed that for sign up it expects:-

<%= devise_error_messages! %> But for sign in it expects some other alert message tag to be referenced, but didn't get the exact info of what is that alert tag which i must use and wher to use ???

Please provide some suggestions !!!

Thanks in advance.

Atlast after some good amount of searching/browsing I found the answer,
you have to add the following piece of code in our application.html.erb file

  <%- flash.each do |name, msg| -%>
    <%= content_tag :div, msg, :id => "flash_#{name}" if msg.is_a?(String) %>
  <%- end -%>  

After adding this I was able to see the sign_in failures alert messages :).

Admittedly, a bit hacky, but I'm using this helper (app/helpers/devise_helper.rb) to grab flashes and use those if set then default to resource.errors. This is just based on the helper that's in the devise lib.

module DeviseHelper

  def devise_error_messages!
    flash_alerts = []
    error_key = 'errors.messages.not_saved'

    if !flash.empty?
      flash_alerts.push(flash[:error]) if flash[:error]
      flash_alerts.push(flash[:alert]) if flash[:alert]
      flash_alerts.push(flash[:notice]) if flash[:notice]
      error_key = 'devise.failure.invalid'
    end

    return "" if resource.errors.empty? && flash_alerts.empty?
    errors = resource.errors.empty? ? flash_alerts : resource.errors.full_messages

    messages = errors.map { |msg| content_tag(:li, msg) }.join
    sentence = I18n.t(error_key, :count    => errors.count,
                                 :resource => resource.class.model_name.human.downcase)

    html = <<-HTML
    <div id="error_explanation">
      <h2>#{sentence}</h2>
      <ul>#{messages}</ul>
    </div>
    HTML

    html.html_safe
  end

end

Rails 5.1, Devise 4.4.3

Inside of a form, errors can be displayed with:

<% resource.errors.full_messages.each do |msg| %>
    <%= msg %>
<% end %>

I know this is old but I ended up here because I was having the same problem in rails 5.1 and the accepted answer didn't worked, so here's what I did. After overriding Devise::SessionController, add the following code to it:

after_action :unauthenticated

protected

def unauthenticated
  flash[:alert] = t("devise.failure.#{request.env['warden'].message}") unless request.env['warden'].message.blank?
end

Also, on the same controller, copy and paste the code for the create method from your version of Devise, and remove the ! from warden.authenticate!. Because you removed the !, now you have to check if the resource is nil, and redirect if it is. In my case, the create method ended up like this:

def create
  self.resource = warden.authenticate(auth_options)
  redirect_to root_path and return if resource.nil?
  set_flash_message!(:notice, :signed_in)
  sign_in(resource_name, resource)
  yield resource if block_given?
  respond_with resource, location: after_sign_in_path_for(resource)
end

Finally, you just have to print the flash messages on your views. I am using materialize, so I created a partial and added the following code to it (which you should customize to your own needs):

<% flash.each do |type, message| %>
  <% if type == "notice" %>
    <script id="toast">
      $(function() {
        Materialize.toast('<%= message %>', 4000);
      });
    </script>
  <% elsif type == "success" %>
    <script id="toast">
      $(function() {
        Materialize.toast('<%= message %>', 4000, 'green');
      });
    </script>
  <% elsif type == "alert" %>
    <script id="toast">
      $(function() {
        Materialize.toast('<%= message %>', 4000, 'orange');
      });
    </script>
  <% end %>
<% end %>