Module: Forestify::InstanceMethods

Defined in:
lib/forestify.rb

Instance Method Summary collapse

Instance Method Details

#children ⇒ Object

Returns an ActiveRecord::Relation looking for descendents.

Example :

@audi.children.all # => []
@vehicle.children.all # => [@car, @plane, @boat, @audi]



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# File 'lib/forestify.rb', line 114

def children
  [] if leaf?
  self.class.where('forestify_left_position > ?', self.forestify_left_position).where('forestify_right_position < ?', self.forestify_right_position)
end

#initialize_position ⇒ Object

Initialize position fields Should be run only once



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# File 'lib/forestify.rb', line 48

def initialize_position
  # @parent = -1 is the option 'No parent'
  if @parent_id.nil? || @parent_id == "-1"
    # No parent has been specified, we need to add this leaf
    # to the right side of the last root node.
    last = self.class.order("forestify_right_position DESC").first
    self.forestify_left_position = (last.nil?) ? 0 : last.forestify_right_position + 1
    self.forestify_right_position = self.forestify_left_position + 1
    self.forestify_level = 0
  else
    @parent_id = @parent_id.to_i
    p = self.class.find(@parent_id)
    self.forestify_left_position = p.forestify_right_position
    self.forestify_right_position = self.forestify_left_position + 1
    self.forestify_level = p.forestify_level + 1
    # update nodes on the right hand side of parent
    self.class.update_all "forestify_left_position = forestify_left_position + 2", ['forestify_left_position > ?', p.forestify_right_position]
    self.class.update_all "forestify_right_position = forestify_right_position + 2", ['forestify_right_position > ?', p.forestify_right_position]
    # update parent
    p.update_attribute 'forestify_right_position', p.forestify_right_position + 2
  end
end

#leaf? ⇒ Boolean

Returns whether the instance is a leaf or not.

Example :

@car.leaf? # => false
@animal.leaf? # => true

Returns:

  • (Boolean) 


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# File 'lib/forestify.rb', line 151

def leaf?
  !node?
end

#node? ⇒ Boolean

Returns whether the instance is a node or not.

Example :

@car.node? # => true
@animal.node? # => false

Returns:

  • (Boolean) 


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# File 'lib/forestify.rb', line 140

def node?
  (self.forestify_right_position - self.forestify_left_position) > 1
end

#parent ⇒ Object

Returns the direct parent, or nil if none exists.

Example :

@vehicle.parent # => nil
@car.parent # => @vehicle



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# File 'lib/forestify.rb', line 103

def parent
  self.parents.where('forestify_level = ?', self.forestify_level - 1).first
end

#parents ⇒ Object

Returns an ActiveRecord::Relation looking for ancestors.

Example :

@audi.parents.all # => [@vehicle, @car]



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# File 'lib/forestify.rb', line 92

def parents
  self.class.where('forestify_left_position < ?', self.forestify_left_position).where('forestify_right_position > ?', self.forestify_right_position)
end

#siblings ⇒ Object

Returns an ActiveRecord::Relation looking for siblings.

Example :

@vehicle.siblings.all => # [@animal]



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# File 'lib/forestify.rb', line 125

def siblings
  if self.parent.nil?
    self.class.where('forestify_level = 0').where('id != ?', self.id)
  else
    self.parent.children.where('forestify_level = ?', self.forestify_level).where('id != ?', self.id)
  end
end

#update_positions_after_delete ⇒ Object 



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# File 'lib/forestify.rb', line 71

def update_positions_after_delete
  if node?
    # Update nodes to the right
    self.class.update_all "forestify_left_position = forestify_left_position - 2", ['forestify_left_position > ?', self.forestify_right_position]
    self.class.update_all "forestify_right_position = forestify_right_position - 2", ['forestify_right_position > ?', self.forestify_right_position]
    # Update children
    self.class.update_all "forestify_level = forestify_level - 1", ['forestify_left_position > ? AND forestify_right_position < ?', self.forestify_left_position, self.forestify_right_position]
    self.class.update_all "forestify_left_position = forestify_left_position - 1, forestify_right_position = forestify_right_position - 1", ['forestify_left_position > ? AND forestify_right_position < ?', self.forestify_left_position, self.forestify_right_position]
  else
    # Update nodes to the right
    self.class.update_all "forestify_left_position = forestify_left_position - 2", ['forestify_left_position > ?', self.forestify_right_position]
    self.class.update_all "forestify_right_position = forestify_right_position - 2", ['forestify_right_position > ?', self.forestify_right_position]
  end
end