Authentication with Rails 3.2.7 using devise 2.0.4, netzke-core 0.7.6 and Ext JS 4.0.2

login.rb

# The Login component
# Lets user type in their credentials, so they can authenticate themselves
class Sessions::Login < Netzke::Base

  # Set the EXT JS class
  js_base_class 'Ext.Window'
 
  # Configure the component
  #
  # @return [Hash]
  def configuration
    super.merge(
      :title => "Login",
      :layout => 'fit',
      :hidden => false,
      :width => 350, 
      :y => 100,
      :auto_height => true,
      :closable => false, 
      :resizable => false,
      :items => [{
        :xtype => :form,
        :frame => true,
        :buttons => [:create_user_session.action],
        :url => Netzke::Core.controller.new_user_session_path(:format => :json),
        :default_type => :textfield,
        :defaults => { 
          :anchor => '100%', 
          :allowBlank => false, 
          :enable_key_events => true,
          :listeners => {
            :special_key => <<-JS.l
              function(field, e)
              {
                // if user presses ENTER => call onSignIn()
                if(e.getKey() == Ext.EventObject.ENTER)
                {
                  field.up('window').onCreateUserSession();
                }
              } 
            JS
          }
        },
        :items => [{
          :name => 'user[login]',
          :field_label => User.human_attribute_name(:login)
        },{
          :name => 'user[password]',
          :field_label => User.human_attribute_name(:password),
          :input_type => :password
        }]
      }]
    )
  end
  
  # Sign in button
  action :create_user_session, :form_bind => true, :icon => '/images/icons/actions/create_user_session.png'
  
  # On sign in
  # Success: Redirect to the path that the server returns
  # Failuer: Show alert               
  js_method :on_create_user_session, <<-JS
    function() {
      var form = this.query('form')[0].getForm();
      if (form.isValid()) {
        form.submit({success: function(form, action) {
                       window.location = action.result.redirect_to;
                    },
                    failure: function(form, action) {
                        Ext.Msg.alert(action.result.errors.message, action.result.errors.reason);
                    }});
      }
    }
  JS

  # Submit form on enter and set focus on login
  js_method :init_component, <<-JS
    function() {
      // Call parent
      this.callParent();
      
      // Get the login textfield
      var textfield = this.query('textfield')[0];
      
      // set focus on login textfield
      textfield.on('afterrender', function(){this.focus();})
    }
  JS
             
end

sessions_controller.rb

# This conroller handles signing in and signing out
# See the devise gem for more information
class SessionsController < Devise::SessionsController
  
  # Of course, skip authorization for this class, since we DO authorization here
  # (it's cancan stuff, so if you don't use cancan, remove this line)
  skip_authorize_resource
  
  # The action for login
  # If format is html => render login form
  # If format is json => Say that something went wrong
  def new
    respond_to do |format|
      format.html { super }
      format.json {render :json => {:success => false, :errors => {:message => I18n.t('session.sign_in.failed.message'),
                                                                   :reason => I18n.t('session.sign_in.failed.wrong_password')}}}
    end
  end
  
  # Try to authorize a user
  # If it fails => redirect to #new
  def create
    respond_to do |format|  
      format.html { super }
      format.json {  
        warden.authenticate!(:scope => resource_name, :recall => "#{controller_path}#new")
        render :status => 200, :json => {:success => true, :redirect_to => session[:user_return_to] || after_sign_in_path_for(:user)}  
      }  
    end
  end
  
  # Define the default path after signing in
  # 
  # @param [Object, Symbol] resource_or_scope
  def after_sign_in_path_for(resource_or_scope)
    home_path
  end
  
  # Define the default path after signing out
  #
  # @param [Object, Symbol] resource_or_scope
  def after_sign_out_path_for(resource_or_scope)
    new_user_session_path
  end
end