Module: Dag

Defined in:
lib/dag/dag.rb,
lib/dag/edges.rb,
lib/dag/columns.rb,
lib/dag/standard.rb,
lib/dag/validators.rb,
lib/dag/polymorphic.rb,
lib/dag/poly_columns.rb

Defined Under Namespace

Modules: Columns, Edges, PolyColumns, Polymorphic, Standard Classes: CreateCorrectnessValidator, UpdateCorrectnessValidator

Instance Method Summary collapse

Instance Method Details

Sets up a model to act as dag links for models specified under the :for option



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# File 'lib/dag/dag.rb', line 4

def acts_as_dag_links(options = {})
  conf = {
          :ancestor_id_column => 'ancestor_id',
          :ancestor_type_column => 'ancestor_type',
          :descendant_id_column => 'descendant_id',
          :descendant_type_column => 'descendant_type',
          :direct_column => 'direct',
          :count_column => 'count',
          :polymorphic => false,
          :node_class_name => nil}
  conf.update(options)

  unless conf[:polymorphic]
    if conf[:node_class_name].nil?
      raise ActiveRecord::ActiveRecordError, 'ERROR: Non-polymorphic graphs need to specify :node_class_name with the receiving class like belong_to'
    end
  end

  class_attribute :acts_as_dag_options, :instance_writer => false
  self.acts_as_dag_options = conf

  extend Columns
  include Columns

  #access to _changed? and _was for (edge,count) if not default
  unless direct_column_name == 'direct'
    module_eval <<-"end_eval", __FILE__, __LINE__
				def direct_changed?
					self.#{direct_column_name}_changed?
				end
				def direct_was
					self.#{direct_column_name}_was
				end
    end_eval
  end

  unless count_column_name == 'count'
    module_eval <<-"end_eval", __FILE__, __LINE__
				def count_changed?
					self.#{count_column_name}_changed?
				end
				def count_was
					self.#{count_column_name}_was
				end
    end_eval
  end

  internal_columns = [ancestor_id_column_name, descendant_id_column_name]
  edge_class_name = self.to_s

  direct_column_name.intern
  count_column_name.intern

  #links to ancestor and descendant
  if acts_as_dag_polymorphic?
    extend PolyColumns
    include PolyColumns

    internal_columns << ancestor_type_column_name
    internal_columns << descendant_type_column_name

    belongs_to :ancestor, :polymorphic => true
    belongs_to :descendant, :polymorphic => true

    validates ancestor_type_column_name.to_sym, :presence => true
    validates descendant_type_column_name.to_sym, :presence => true
    validates ancestor_id_column_name.to_sym, :uniqueness => {:scope => [ancestor_type_column_name, descendant_type_column_name, descendant_id_column_name]}

    scope :with_ancestor, lambda { |ancestor| where(ancestor_id_column_name => ancestor.id, ancestor_type_column_name => ancestor.class.to_s) }
    scope :with_descendant, lambda { |descendant| where(descendant_id_column_name => descendant.id, descendant_type_column_name => descendant.class.to_s) }

    scope :with_ancestor_point, lambda { |point| where(ancestor_id_column_name => point.id, ancestor_type_column_name => point.type) }
    scope :with_descendant_point, lambda { |point| where(descendant_id_column_name => point.id, descendant_type_column_name => point.type) }

    extend Polymorphic
    include Polymorphic
  else
    belongs_to :ancestor, :foreign_key => ancestor_id_column_name, :class_name => acts_as_dag_options[:node_class_name]
    belongs_to :descendant, :foreign_key => descendant_id_column_name, :class_name => acts_as_dag_options[:node_class_name]

    validates ancestor_id_column_name.to_sym, :uniqueness => {:scope => [descendant_id_column_name]}

    scope :with_ancestor, lambda { |ancestor| where(ancestor_id_column_name => ancestor.id) }
    scope :with_descendant, lambda { |descendant| where(descendant_id_column_name => descendant.id) }

    scope :with_ancestor_point, lambda { |point| where(ancestor_id_column_name => point.id) }
    scope :with_descendant_point, lambda { |point| where(descendant_id_column_name => point.id) }

    extend Standard
    include Standard
  end

  # TODO: rename? breaks when using 'where' query because :direct scope name and :direct => true parameter conflict?
  scope :direct, :conditions => {:direct => true}
  scope :indirect, :conditions => {:direct => false}

  scope :ancestor_nodes, :joins => :ancestor
  scope :descendant_nodes, :joins => :descendant

  validates ancestor_id_column_name.to_sym, :presence => true,
            :numericality => true
  validates descendant_id_column_name.to_sym, :presence => true,
            :numericality => true

  extend Edges
  include Edges

  before_destroy :destroyable!, :perpetuate
  before_save :perpetuate
  before_validation :field_check, :fill_defaults, :on => :update
  before_validation :fill_defaults, :on => :create

  include ActiveModel::Validations
  validates_with CreateCorrectnessValidator, :on => :create
  validates_with UpdateCorrectnessValidator, :on => :update


  #internal fields
  code = 'def field_check ' + "\n"
  internal_columns.each do |column|
    code +=  "if " + column + "_changed? \n" + ' raise ActiveRecord::ActiveRecordError, "Column: '+column+' cannot be changed for an existing record it is immutable"' + "\n end \n"
  end
  code += 'end'
  module_eval code

  [count_column_name].each do |column|
    module_eval <<-"end_eval", __FILE__, __LINE__
				def #{column}=(x)
					raise ActiveRecord::ActiveRecordError, "ERROR: Unauthorized assignment to #{column}: it's an internal field handled by acts_as_dag code."
				end
    end_eval
  end
end

#has_dag_links(options = {}) ⇒ Object 



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# File 'lib/dag/dag.rb', line 138

def has_dag_links(options = {})
  conf = {
          :class_name => nil,
          :prefix => '',
          :ancestor_class_names => [],
          :descendant_class_names => []
  }
  conf.update(options)

  #check that class_name is filled
  if conf[:link_class_name].nil?
    raise ActiveRecord::ActiveRecordError, "has_dag_links must be provided with :link_class_name option"
  end

  #add trailing '_' to prefix
  unless conf[:prefix] == ''
    conf[:prefix] += '_'
  end

  prefix = conf[:prefix]
  dag_link_class_name = conf[:link_class_name]
  dag_link_class = conf[:link_class_name].constantize

  if dag_link_class.acts_as_dag_polymorphic?
    self.class_eval <<-EOL
            has_many :#{prefix}links_as_ancestor, :as => :ancestor, :class_name => '#{dag_link_class_name}'
            has_many :#{prefix}links_as_descendant, :as => :descendant, :class_name => '#{dag_link_class_name}'

            has_many :#{prefix}links_as_parent, :as => :ancestor, :class_name => '#{dag_link_class_name}', :conditions => {'#{dag_link_class.direct_column_name}' => true}
            has_many :#{prefix}links_as_child, :as => :descendant, :class_name => '#{dag_link_class_name}', :conditions => {'#{dag_link_class.direct_column_name}' => true}

    EOL

    ancestor_table_names = []
    parent_table_names = []
    conf[:ancestor_class_names].each do |class_name|
      table_name = class_name.tableize
      self.class_eval <<-EOL2
              has_many :#{prefix}links_as_descendant_for_#{table_name}, :as => :descendant, :class_name => '#{dag_link_class_name}', :conditions => {'#{dag_link_class.ancestor_type_column_name}' => '#{class_name}'}
              has_many :#{prefix}ancestor_#{table_name}, :through => :#{prefix}links_as_descendant_for_#{table_name}, :source => :ancestor, :source_type => '#{class_name}'
              has_many :#{prefix}links_as_child_for_#{table_name}, :as => :descendant, :class_name => '#{dag_link_class_name}', :conditions => {'#{dag_link_class.ancestor_type_column_name}' => '#{class_name}','#{dag_link_class.direct_column_name}' => true}
              has_many :#{prefix}parent_#{table_name}, :through => :#{prefix}links_as_child_for_#{table_name}, :source => :ancestor, :source_type => '#{class_name}'

            	def #{prefix}root_for_#{table_name}?
							self.links_as_descendant_for_#{table_name}.empty?
          		end
      EOL2
      ancestor_table_names << (prefix+'ancestor_'+table_name)
      parent_table_names << (prefix+'parent_'+table_name)
      unless conf[:descendant_class_names].include?(class_name)
        #this apparently is only one way is we can create some aliases making things easier
        self.class_eval "has_many :#{prefix}#{table_name}, :through => :#{prefix}links_as_descendant_for_#{table_name}, :source => :ancestor, :source_type => '#{class_name}'"
      end
    end

    unless conf[:ancestor_class_names].empty?
      self.class_eval <<-EOL25
						def #{prefix}ancestors
							#{ancestor_table_names.join(' + ')}
						end
						def #{prefix}parents
							#{parent_table_names.join(' + ')}
						end
      EOL25
    else
      self.class_eval <<-EOL26
						def #{prefix}ancestors
							a = []
							#{prefix}links_as_descendant.each do |link|
								a << link.ancestor
							end
							a
						end
						def #{prefix}parents
							a = []
							#{prefix}links_as_child.each do |link|
								a << link.ancestor
							end
							a
						end
      EOL26
    end

    descendant_table_names = []
    child_table_names = []
    conf[:descendant_class_names].each do |class_name|
      table_name = class_name.tableize
      self.class_eval <<-EOL3
              has_many :#{prefix}links_as_ancestor_for_#{table_name}, :as => :ancestor, :class_name => '#{dag_link_class_name}', :conditions => {'#{dag_link_class.descendant_type_column_name}' => '#{class_name}'}
              has_many :#{prefix}descendant_#{table_name}, :through => :#{prefix}links_as_ancestor_for_#{table_name}, :source => :descendant, :source_type => '#{class_name}'

              has_many :#{prefix}links_as_parent_for_#{table_name}, :as => :ancestor, :class_name => '#{dag_link_class_name}', :conditions => {'#{dag_link_class.descendant_type_column_name}' => '#{class_name}','#{dag_link_class.direct_column_name}' => true}
              has_many :#{prefix}child_#{table_name}, :through => :#{prefix}links_as_parent_for_#{table_name}, :source => :descendant, :source_type => '#{class_name}'

						def #{prefix}leaf_for_#{table_name}?
              	self.links_as_ancestor_for_#{table_name}.empty?
            	end
      EOL3
      descendant_table_names << (prefix+'descendant_'+table_name)
      child_table_names << (prefix+'child_'+table_name)
      unless conf[:ancestor_class_names].include?(class_name)
        self.class_eval "has_many :#{prefix}#{table_name}, :through => :#{prefix}links_as_ancestor_for_#{table_name}, :source => :descendant, :source_type => '#{class_name}'"
      end
    end

    unless conf[:descendant_class_names].empty?
      self.class_eval <<-EOL35
						def #{prefix}descendants
							#{descendant_table_names.join(' + ')}
						end
						def #{prefix}children
							#{child_table_names.join(' + ')}
						end
      EOL35
    else
      self.class_eval <<-EOL36
						def #{prefix}descendants
							d = []
							#{prefix}links_as_ancestor.each do |link|
								d << link.descendant
							end
							d
						end
						def #{prefix}children
							d = []
							#{prefix}links_as_parent.each do |link|
								d << link.descendant
							end
							d
						end
      EOL36
    end
  else
    self.class_eval <<-EOL4
            has_many :#{prefix}links_as_ancestor, :foreign_key => '#{dag_link_class.ancestor_id_column_name}', :class_name => '#{dag_link_class_name}'
            has_many :#{prefix}links_as_descendant, :foreign_key => '#{dag_link_class.descendant_id_column_name}', :class_name => '#{dag_link_class_name}'

            has_many :#{prefix}ancestors, :through => :#{prefix}links_as_descendant, :source => :ancestor
            has_many :#{prefix}descendants, :through => :#{prefix}links_as_ancestor, :source => :descendant

            has_many :#{prefix}links_as_parent, :foreign_key => '#{dag_link_class.ancestor_id_column_name}', :class_name => '#{dag_link_class_name}', :conditions => {'#{dag_link_class.direct_column_name}' => true}
            has_many :#{prefix}links_as_child, :foreign_key => '#{dag_link_class.descendant_id_column_name}', :class_name => '#{dag_link_class_name}', :conditions => {'#{dag_link_class.direct_column_name}' => true}

            has_many :#{prefix}parents, :through => :#{prefix}links_as_child, :source => :ancestor
            has_many :#{prefix}children, :through => :#{prefix}links_as_parent, :source => :descendant

    EOL4
  end
  self.class_eval <<-EOL5
          def #{prefix}self_and_ancestors
            [self] + #{prefix}ancestors
          end
          def #{prefix}self_and_descendants
            [self] + #{prefix}descendants
          end
          
          def #{prefix}leaf?
            self.#{prefix}links_as_ancestor.empty?
				end
				def #{prefix}root?
					self.#{prefix}links_as_descendant.empty?
				end
  EOL5
end