Implement Null Object pattern for Todo.project to save bsag and I some script/console headaches. Thanks to

Craig Ambrose for the "writeup":http://blog.craigambrose.com/articles/2006/09/22/active-record-associations-and-the-null-object-pattern



git-svn-id: http://www.rousette.org.uk/svn/tracks-repos/trunk@342 a4c988fc-2ded-0310-b66e-134b36920a42

tracks/app/models/project.rb

@@ -33,6 +33,10 @@ class Project < ActiveRecord::Base
   
   attr_protected :user
 
+  def self.null_object
+    NullProject.new
+  end
+  
   def description_present?
     attribute_present?("description")
   end
@@ -42,3 +46,15 @@ class Project < ActiveRecord::Base
   end
       
 end
+
+class NullProject
+  
+  def hidden?
+    false
+  end
+  
+  def nil?
+    true
+  end
+  
+end

tracks/app/models/todo.rb

@@ -14,6 +14,12 @@ class Todo < ActiveRecord::Base
   validates_length_of :notes, :maximum => 60000, :allow_nil => true 
   # validates_chronic_date :due, :allow_nil => true
 
+  alias_method :original_project, :project
+
+  def project
+    original_project.nil? ? Project.null_object : original_project
+  end
+  
   def self.not_done( id=id )
     self.find(:all, :conditions =>[ "done = ? AND context_id = ?", false, id], :order =>"due IS NULL, due ASC, created_at ASC")
   end