module ActionDispatch class Request # Access the contents of the flash. Use flash["notice"] to # read a notice you put there or flash["notice"] = "hello" # 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 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 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] %> #
<%= flash[:notice] %>
# <% 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 ([]=). # When you need to pass an object to the current action, you use now, and your object will # vanish when the current action is done. # # Entries set via now are accessed the same way as standard entries: flash['my-key']. 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 keep and discard 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']) && (flash = session['flash']) && flash.empty? session.delete('flash') end end end end