Module: TaggableModel::ClassMethods

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# File 'lib/taggable_model.rb', line 16

def is_taggable
  return if is_taggable?

  has_many :taggings, :as => :tagged
  has_many :attached_tags, :through => :taggings, :source => :tag    # can't be just has_many :tags because that stomps on the radius tags in Page.
  
  named_scope :from_tags, lambda { |tags| 
    {
      :joins => "INNER JOIN taggings as tt on tt.tagged_id = #{self.table_name}.id AND tt.tagged_type = '#{self.to_s}'", 
      :conditions => ["tt.tag_id in(#{tags.map{ '?' }.join(',')})"] + tags.map(&:id),
      :group => column_names.map { |n| table_name + '.' + n }.join(','),    # postgres is strict and requires that we group by all selected (but not aggregated) columns
      :order => "count(tt.id) DESC",
      :readonly => false
    }
  }

  named_scope :from_all_tags, lambda { |tags| 
    {
      :joins => "INNER JOIN taggings as tt on tt.tagged_id = #{self.table_name}.id AND tt.tagged_type = '#{self.to_s}'", 
      :conditions => ["tt.tag_id in(#{tags.map{ '?' }.join(',')})"] + tags.map(&:id),
      :group => column_names.map { |n| table_name + '.' + n }.join(','),    # postgres is strict and requires that we group by all selected (but not aggregated) columns
      :having => "count(tt.id) >= #{tags.length}",
      :readonly => false
    }
  } do
    # count is badly sugared here: it omits the group and having clauses.
    # length performs the query and looks at the array: less neat, but more right
    # this gives us back any? and empty? as well.
    def count
      length
    end
  end
  
  # this sets up eg Taggings.of_model
  # and then uses that to define instance methods in Tag:
  # tag.models
  # tag.models_count
  Tag.define_class_retrieval_methods(self.to_s)
  
  class_eval {
    extend TaggableModel::TaggableClassMethods
    include TaggableModel::TaggableInstanceMethods
    alias_method "related_#{self.to_s.underscore.pluralize}".intern, :related
    alias_method "closely_related_#{self.to_s.underscore.pluralize}".intern, :closely_related
  }

  ActiveRecord::Base.taggable_models.push(self.to_s.intern)
end