The flash provides a way to pass temporary objects between actions.
Anything you place in the flash will be exposed to the very next action and
then cleared out. This is a great way of doing notices and alerts, such as
a create action that sets flash[:notice] = "Successfully
created" before redirecting to a display action that can then
expose the flash to its template. Actually, that exposure is automatically
done. Example:
class WeblogController < ActionController::Base
def create
# save post
flash[:notice] = "Successfully created post"
redirect_to :action => "display", :params => { :id => post.id }
end
def display
# doesn't need to assign the flash notice to the template, that's done automatically
end
end
display.erb
<% if flash[:notice] %><div class="notice"><%= flash[:notice] %></div><% end %>
This example just places a string in the flash, but you can put any object
in there. And of course, you can put as many as you like at a time too.
Just remember: They‘ll be gone by the time the next action has been
performed.
See docs on the FlashHash class for more
details about the flash.