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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 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.rhtml
# <% 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.append_features(base) #:nodoc:
super
base.before_filter(:fire_flash)
base.after_filter(:sweep_flash)
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
@@avoid_sweep = false
cattr_accessor :avoid_sweep
def initialize #:nodoc:
super
@used = {}
end
def []=(k, v) #:nodoc:
keep(k)
super
end
def update h #:nodoc:
h.keys.each{|k| discard 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.keep # keep entire flash available for the next action
# flash.discard(:warning) # discard the "warning" entry (it'll still be available for 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:
return if @@avoid_sweep
keys.each do |k|
unless @used[k]
use(k)
else
delete(k)
@used.delete(k)
end
end
(@used.keys - keys).each{|k| @used.delete k } # clean up after keys that could have been left over by calling reject! or shift on the flash
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
protected
# 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:
@session['flash'] ||= FlashHash.new
end
# deprecated. use <tt>flash.keep</tt> instead
def keep_flash #:doc:
flash.keep
end
private
# marks flash entries as used and expose the flash to the view
def fire_flash
flash.discard
@assigns["flash"] = flash
end
# deletes the flash entries that were not marked for keeping
def sweep_flash
flash.sweep
end
end
end
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