coreyti/application.html.erb

## application.html.erb
### in Rails.root.join('app/views/layouts/application.html.erb')

# render `flash[:alert]` and `flash[:notice]`, if unclaimed (by a scoped usage)
<body>
  <p class="alert alert-error">
    <%= flash[:alert] %>
  </p>

  <p class="alert alert-info">
    <%= flash[:notice] %>
  </p>

  <!-- stuff... -->
<body>

## auth.rb
### in Rails.root.join('config/initializers/auth.rb')

# define custom FailureApp for Devise to add indication of scoped flash messages.
# the point here is, when Warden invalidates a session#create attempt, it exits
# quickly and before loading the resource. hence, Devise cannot place errors on
# a resource. instead, it resorts to using the `flash`. so, we add a workaround.
module MyAppName
  module Auth
    class FailureApp < Devise::FailureApp
      def recall
        flash.now[scope] = [:alert]
        super
      end
    end
  end
end

## devise.rb
### in Rails.root.join('config/initializers/devise.rb')

# update Devise setup to use custom FailureApp.
Devise.setup do |config|
  # stuff...

  config.warden do |manager|
    manager.failure_app = MyAppName::Auth::FailureApp
  end

  # stuff...
end

## form.rb
### in Rails.root.join('config/initializers/form.rb')

# define custom FormBuilder and set it as default.
module MyAppName
  class FormBuilder < SimpleForm::FormBuilder
    # look for scoped flash message keys: `flash[:user] = [:alert, :notice]`.
    # if found and for each key, capture and delete matching message from
    # top-level flash. build html to render the message.
    def flash(*args)
      template.flash[object_name] ||= []
      mapping = { :alert => :error, :notice => :info }
      args.map do |arg|
        if template.flash[object_name].include?(arg)
          message = (text = template.flash[arg]) && template.flash.delete(arg) && text
          html    = <<-HTML
          <p class="alert alert-#{mapping[arg]}">
            <strong>#{arg}:</strong>
            #{message}
            <button type="button" class="close" data-dismiss="alert">x</button>
          </p>
          HTML
        end
      end.join.html_safe
    end
  end
end

ActionView::Base.default_form_builder = MyAppName::FormBuilder

## new.html.erb
### in Rails.root.join('app/views/users/sessions/new.html.erb')

# use FormBuilder#flash to render messages.
<h2>Sign in</h2>

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

  <%#
    if, e.g., `flash[:user]` is `[:alert]`, we use up, the
    `flash[:alert]` message here. otherwise, leave it for top-level access.
  %>
  <%= f.flash(:alert, :notice) %>

  <div class="form-inputs">
    <%= f.input :email, :required => false, :autofocus => true %>
    <%= f.input :password, :required => false %>
    <%= f.input :remember_me, :as => :boolean if devise_mapping.rememberable? %>
  </div>

  <div class="form-actions">
    <%= f.button :submit, "Sign in" %>
  </div>
<% end %>

<%= render "devise/shared/links" %>
	### in Rails.root.join('app/views/layouts/application.html.erb')

	# render `flash[:alert]` and `flash[:notice]`, if unclaimed (by a scoped usage)
	<body>
	<p class="alert alert-error">
	<%= flash[:alert] %>
	</p>

	<p class="alert alert-info">
	<%= flash[:notice] %>
	</p>

	<!-- stuff... -->
	<body>
	### in Rails.root.join('config/initializers/auth.rb')

	# define custom FailureApp for Devise to add indication of scoped flash messages.
	# the point here is, when Warden invalidates a session#create attempt, it exits
	# quickly and before loading the resource. hence, Devise cannot place errors on
	# a resource. instead, it resorts to using the `flash`. so, we add a workaround.
	module MyAppName
	module Auth
	class FailureApp < Devise::FailureApp
	def recall
	flash.now[scope] = [:alert]
	super
	end
	end
	end
	end
	### in Rails.root.join('config/initializers/devise.rb')

	# update Devise setup to use custom FailureApp.
	Devise.setup do \|config\|
	# stuff...

	config.warden do \|manager\|
	manager.failure_app = MyAppName::Auth::FailureApp
	end

	# stuff...
	end
	### in Rails.root.join('config/initializers/form.rb')

	# define custom FormBuilder and set it as default.
	module MyAppName
	class FormBuilder < SimpleForm::FormBuilder
	# look for scoped flash message keys: `flash[:user] = [:alert, :notice]`.
	# if found and for each key, capture and delete matching message from
	# top-level flash. build html to render the message.
	def flash(*args)
	template.flash[object_name] \|\|= []
	mapping = { :alert => :error, :notice => :info }
	args.map do \|arg\|
	if template.flash[object_name].include?(arg)
	message = (text = template.flash[arg]) && template.flash.delete(arg) && text
	html = <<-HTML
	<p class="alert alert-#{mapping[arg]}">
	<strong>#{arg}:</strong>
	#{message}
	<button type="button" class="close" data-dismiss="alert">x</button>
	</p>
	HTML
	end
	end.join.html_safe
	end
	end
	end

	ActionView::Base.default_form_builder = MyAppName::FormBuilder
	### in Rails.root.join('app/views/users/sessions/new.html.erb')

	# use FormBuilder#flash to render messages.
	<h2>Sign in</h2>

	<%= form_for(resource, {
	:as => resource_name,
	:url => session_path(resource_name)
	}) do \|f\| %>

	<%#
	if, e.g., `flash[:user]` is `[:alert]`, we use up, the
	`flash[:alert]` message here. otherwise, leave it for top-level access.
	%>
	<%= f.flash(:alert, :notice) %>

	<div class="form-inputs">
	<%= f.input :email, :required => false, :autofocus => true %>
	<%= f.input :password, :required => false %>
	<%= f.input :remember_me, :as => :boolean if devise_mapping.rememberable? %>
	</div>

	<div class="form-actions">
	<%= f.button :submit, "Sign in" %>
	</div>
	<% end %>

	<%= render "devise/shared/links" %>