I made a wiki page within the devise wiki on github for How To: Integrate I18n Flash Messages with Devise and Bootstrap
Flash Messages For the Site
First we will make a rendered view to make the code concise. Within "app/views/layouts/application.html.erb" I added <%= render 'layouts/messages' %>.
My file looks like:
<body>
<%= render 'layouts/header' %>
<div class="container">
<%= render 'layouts/messages' %>
<%= yield %>
<%= render 'layouts/footer' %>
</div>
</body>
Next we have to make the messages file. Make a new file in "app/views/layouts/_messages.html.erb" and add:
<% flash.each do |key, value| %>
<div class="alert alert-<%= key %>">
<a href="#" data-dismiss="alert" class="close">×</a>
<ul>
<li>
<%= value %>
</li>
</ul>
</div>
<% end %>
This will give us flash messages for the entire site.
Flash Messages For Devise
For devise you need to override the way devise handles flash messages. Create a file called devise_helper in "app/helpers/devise_helper.rb".
Inside the file you have to create a method called devise_error_messages!, which is the name of the file that tells devise how to handle flash messages.
module DeviseHelper
def devise_error_messages!
return '' if resource.errors.empty?
messages = resource.errors.full_messages.map { |msg| content_tag(:li, msg) }.join
html = <<-HTML
<div class="alert alert-error alert-block"> <button type="button"
class="close" data-dismiss="alert">x</button>
#{messages}
</div>
HTML
html.html_safe
end
end
Next in your devise views you will have to define where you want the error messages to appear. You will need to enter <%= devise_error_messages! %> within the devise pages. An example is entering this within "app/views/devise/registrations/.new.html.erb" (The sign up page)
The method call should already be within the file, but you can move the code around to customize where it is shown.
CSS For Flash Messages
If you do not want to use the odd blue and yellow alerts that come default, I have set error and alert to have the same color and success and notice to have the same color. I am using red for errors and alerts, and green for success and notice.
Within my "app/assets/stylesheets/custom.css.scss" I have:
/*flash*/
.alert-error {
background-color: #f2dede;
border-color: #eed3d7;
color: #b94a48;
text-align: left;
}
.alert-alert {
background-color: #f2dede;
border-color: #eed3d7;
color: #b94a48;
text-align: left;
}
.alert-success {
background-color: #dff0d8;
border-color: #d6e9c6;
color: #468847;
text-align: left;
}
.alert-notice {
background-color: #dff0d8;
border-color: #d6e9c6;
color: #468847;
text-align: left;
}
