#103 Site Wide Announcements

Apr 28, 2008 | 13 minutes | Views, Controllers, Active Record, Refactoring, Ajax

Sometimes you need to display an administrative announcement to every page on the site and give the users the ability to hide the announcement. See how in this episode.

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Update: as Simon pointed out in the comments, there's a problem with the announcement find conditions when passing a hide_time. The code below has been updated with the fix.

          bash
                
        script/generate scaffold announcement message:text starts_at:datetime ends_at:datetime
script/generate controller javascripts
        
script/generate scaffold announcement message:text starts_at:datetime ends_at:datetime
script/generate controller javascripts

          layouts/application.html.erb
                
        <% unless current_announcements.empty? %>
<div id="announcement">
  <% for announcement in current_announcements %>
    <p><%=h announcement.message %></p>
  <% end %>
  <p><%= link_to_remote "Hide this message", :url => "/javascripts/hide_announcement.js" %></p>
</div>
<% end %>
        
        
        
        
        
        
        
        
        
      
<% unless current_announcements.empty? %>
<div id="announcement">
  <% for announcement in current_announcements %>
    <p><%=h announcement.message %></p>
  <% end %>
  <p><%= link_to_remote "Hide this message", :url => "/javascripts/hide_announcement.js" %></p>
</div>
<% end %>

          models/announcement.rb
                
        def self.current_announcements(hide_time)
  with_scope :find => { :conditions => "starts_at <= now() AND ends_at >= now()" } do
    if hide_time.nil?
      find(:all)
    else
      find(:all, :conditions => ["updated_at > ? OR starts_at > ?", hide_time, hide_time])
    end
  end
end
        
        
        
        
        
        
        
        
        
      
def self.current_announcements(hide_time)
  with_scope :find => { :conditions => "starts_at <= now() AND ends_at >= now()" } do
    if hide_time.nil?
      find(:all)
    else
      find(:all, :conditions => ["updated_at > ? OR starts_at > ?", hide_time, hide_time])
    end
  end
end

          application_helper.rb
                
        def current_announcements
  @current_announcements ||= Announcement.current_announcements(session[:announcement_hide_time])
end
        
def current_announcements
  @current_announcements ||= Announcement.current_announcements(session[:announcement_hide_time])
end

          javascripts_controller.rb
                
        def hide_announcement
  session[:announcement_hide_time] = Time.now
end
        
def hide_announcement
  session[:announcement_hide_time] = Time.now
end

          hide_announcement.js.rjs
                
        page[:announcement].hide
        
page[:announcement].hide

          routes.rb
                
        map.connect ":controller/:action.:format"
        
map.connect ":controller/:action.:format"