git-svn-id: http://svn.viney.net.nz/things/rails/plugins/acts_as_tagg…

…able_on_steroids@346 20afb1e0-9c0e-0410-9884-91ed27886737

CHANGELOG

@@ -2,6 +2,8 @@
 
 * Make find_tagged_with correctly apply :conditions
 
+* Add Tag.destroy_unused option.
+
 [11 October 2007]
 
 * Make tag_counts work correctly with STI.

README

@@ -130,6 +130,13 @@ For example, to use spaces instead of commas, add the following to config/enviro
 
   TagList.delimiter = " "
 
+=== Unused tags
+
+Set Tag.destroy_unused to remove tags when they are no longer being
+used to tag any objects. Defaults to false.
+
+  Tag.destroy_unused = true
+
 === Other
 
 Problems, comments, and suggestions all welcome. jonathan.viney@gmail.com  

lib/tag.rb

@@ -4,6 +4,9 @@ class Tag < ActiveRecord::Base
   validates_presence_of :name
   validates_uniqueness_of :name
 
+  cattr_accessor :destroy_unused
+  self.destroy_unused = false
+
   # LIKE is used for cross-database case-insensitivity
   def self.find_or_create_with_like_by_name(name)
     find(:first, :conditions => ["name LIKE ?", name]) || create(:name => name)

lib/tagging.rb

@@ -1,4 +1,10 @@
 class Tagging < ActiveRecord::Base #:nodoc:
   belongs_to :tag
   belongs_to :taggable, :polymorphic => true
+
+  def after_destroy
+    if Tag.destroy_unused and tag.taggings.count.zero?
+      tag.destroy
+    end
+  end
 end

test/acts_as_taggable_test.rb

@@ -291,6 +291,30 @@ def test_case_insensitivity
 
     assert_equal Post.find_tagged_with("Nature"), Post.find_tagged_with("nature")
   end
+
+  def test_tag_not_destroyed_when_unused
+    posts(:jonathan_sky).tag_list.add("Random")
+    posts(:jonathan_sky).save!
+
+    assert_no_difference 'Tag.count' do
+      posts(:jonathan_sky).tag_list.remove("Random")
+      posts(:jonathan_sky).save!
+    end
+  end
+
+  def test_tag_destroyed_when_unused
+    Tag.destroy_unused = true
+
+    posts(:jonathan_sky).tag_list.add("Random")
+    posts(:jonathan_sky).save!
+
+    assert_difference 'Tag.count', -1 do
+      posts(:jonathan_sky).tag_list.remove("Random")
+      posts(:jonathan_sky).save!
+    end
+  ensure
+    Tag.destroy_unused = false
+  end
 end
 
 class ActsAsTaggableOnSteroidsFormTest < Test::Unit::TestCase