aboutsummaryrefslogtreecommitdiffstats
path: root/actionpack/lib/action_controller/flash.rb
blob: 06c8c4b5c6bdfc2bf7c38ff5fc7f2c2a23bd5d3b (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
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