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module ActionController #:nodoc:
# 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 <tt>flash[:notice] = "Successfully created"</tt> before redirecting to a display action that can
# then expose the flash to its template. Actually, that exposure is automatically done. Example:
#
# class PostsController < ActionController::Base
# def create
# # save post
# flash[:notice] = "Successfully created post"
# redirect_to posts_path(@post)
# end
#
# def show
# # doesn't need to assign the flash notice to the template, that's done automatically
# end
# end
#
# show.html.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.
module Flash
def self.included(base)
base.class_eval do
include InstanceMethods
alias_method_chain :perform_action, :flash
alias_method_chain :reset_session, :flash
end
end
class FlashNow #:nodoc:
def initialize(flash)
@flash = flash
end
def []=(k, v)
@flash[k] = v
@flash.discard(k)
v
end
def [](k)
@flash[k]
end
end
class FlashHash < Hash
def initialize #:nodoc:
super
@used = {}
end
def []=(k, v) #:nodoc:
keep(k)
super
end
def update(h) #:nodoc:
h.keys.each { |k| keep(k) }
super
end
alias :merge! :update
def replace(h) #:nodoc:
@used = {}
super
end
# Sets a flash that will not be available to the next action, only to the current.
#
# flash.now[:message] = "Hello current action"
#
# This method enables you to use the flash as a central messaging system in your app.
# When you need to pass an object to the next action, you use the standard flash assign (<tt>[]=</tt>).
# When you need to pass an object to the current action, you use <tt>now</tt>, and your object will
# vanish when the current action is done.
#
# Entries set via <tt>now</tt> are accessed the same way as standard entries: <tt>flash['my-key']</tt>.
def now
FlashNow.new(self)
end
# Keeps either the entire current flash or a specific flash entry available for the next action:
#
# flash.keep # keeps the entire flash
# flash.keep(:notice) # keeps only the "notice" entry, the rest of the flash is discarded
def keep(k = nil)
use(k, false)
end
# Marks the entire flash or a single flash entry to be discarded by the end of the current action:
#
# flash.discard # discard the entire flash at the end of the current action
# flash.discard(:warning) # discard only the "warning" entry at the end of the current action
def discard(k = nil)
use(k)
end
# Mark for removal entries that were kept, and delete unkept ones.
#
# This method is called automatically by filters, so you generally don't need to care about it.
def sweep #:nodoc:
keys.each do |k|
unless @used[k]
use(k)
else
delete(k)
@used.delete(k)
end
end
# clean up after keys that could have been left over by calling reject! or shift on the flash
(@used.keys - keys).each{ |k| @used.delete(k) }
end
private
# Used internally by the <tt>keep</tt> and <tt>discard</tt> methods
# use() # marks the entire flash as used
# use('msg') # marks the "msg" entry as used
# use(nil, false) # marks the entire flash as unused (keeps it around for one more action)
# use('msg', false) # marks the "msg" entry as unused (keeps it around for one more action)
def use(k=nil, v=true)
unless k.nil?
@used[k] = v
else
keys.each{ |key| use(key, v) }
end
end
end
module InstanceMethods #:nodoc:
protected
def perform_action_with_flash
perform_action_without_flash
remove_instance_variable(:@_flash) if defined? @_flash
end
def reset_session_with_flash
reset_session_without_flash
remove_instance_variable(:@_flash) if defined? @_flash
end
# Access the contents of the flash. Use <tt>flash["notice"]</tt> to
# read a notice you put there or <tt>flash["notice"] = "hello"</tt>
# to put a new one.
def flash #:doc:
unless defined? @_flash
@_flash = session["flash"] ||= FlashHash.new
@_flash.sweep
end
@_flash
end
end
end
end
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