The flash provides a way to pass temporary primitive-types (String, Array, Hash) between actions. Anything you place in the flash will be exposed to the very next action and then cleared out.
class PostsController < ActionController::Base
def create
# save post
flash[:notice] = "Post successfully created"
redirect_to @post #redireting to show
end
def show
# doesn't need to assign the flash notice to the template, that's done automatically
#here you can access flash[:notice] too
end
end
show.html.erb
<% if flash[:notice] %>
<div class="notice"><%= flash[:notice] %></div>
<% end %>Since the notice and alert keys are a common idiom, convenience accessors are available:
flash.alert = "You must be logged in" #or flash[:alert]
flash.notice = "Post successfully created" #or flash[:notice]You can use any idiom like:
flash[:flag] = true
puts flash.flag
#undefined method `abcd'
#because flash doesn't provide accessor for this unlike notice and alertPersist flash values against multiple actions:
Now suppose you have three actions say action1, action2 , action3. And you are calling one to another:
def action1
flash.notice = 'check'
redirect_to :action2
end
def action2
puts flash.notice
#'check'
redirect_to :action3
end
def action3
puts flash.notice
#nil
end
#Because flash persist values only for the next action. It will clean the flash object on redirecting to action3.
#keep is used to persist value in flash for the next action.Use of keep:
def action1
flash.notice = 'check'
redirect_to :action2
end
def action2
puts flash.notice
#'check'
flash.keep(:notice)
#keep the notice value for the next action
redirect_to :action3
end
def action3
puts flash.notice
#print 'check'
#now if you redirect to some action4 and want to persist the value of flash you again have to use keep.
endPersisting values just for currect action:
Can’t access these values in next action.
flash.now.notice = "Good luck now!"
#or use flash.now[:notice]