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module ActionDispatch
class Request
# 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
session['flash'] ||= Flash::FlashHash.new
end
end
# 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.
class Flash
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
# Convenience accessor for flash.now[:alert]=
def alert=(message)
self[:alert] = message
end
# Convenience accessor for flash.now[:notice]=
def notice=(message)
self[:notice] = message
end
end
class FlashHash < Hash
def initialize #:nodoc:
super
@used = Set.new
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 = Set.new
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.include?(k)
@used << 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).each{ |k| @used.delete(k) }
end
# Convenience accessor for flash[:alert]
def alert
self[:alert]
end
# Convenience accessor for flash[:alert]=
def alert=(message)
self[:alert] = message
end
# Convenience accessor for flash[:notice]
def notice
self[:notice]
end
# Convenience accessor for flash[:notice]=
def notice=(message)
self[:notice] = message
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)
# Returns the single value for the key you asked to be marked (un)used or the FlashHash itself
# if no key is passed.
def use(key = nil, used = true)
Array(key || keys).each { |k| used ? @used << k : @used.delete(k) }
return key ? self[key] : self
end
end
def initialize(app)
@app = app
end
def call(env)
if (session = env['rack.session']) && (flash = session['flash'])
flash.sweep
end
@app.call(env)
ensure
if (session = env['rack.session']) && session.key?('flash') && session['flash'].empty?
session.delete('flash')
end
end
end
end
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