Module: ActiveRecord::Acts::NestedSet::InstanceMethods

Defined in:
lib/active_record/acts/nested_set.rb

Instance Method Summary collapse

Instance Method Details

#add_child(child) ⇒ Object

Adds a child to this object in the tree. If this object hasn’t been initialized, it gets set up as a root node. Otherwise, this method will update all of the other elements in the tree and shift them to the right, keeping everything balanced.



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# File 'lib/active_record/acts/nested_set.rb', line 140

def add_child( child )     
  self.reload
  child.reload

  if child.root?
    raise "Adding sub-tree isn\'t currently supported"
  else
    if ( (self[left_col_name] == nil) || (self[right_col_name] == nil) )
      # Looks like we're now the root node!  Woo
      self[left_col_name] = 1
      self[right_col_name] = 4
      
      # What do to do about validation?
      return nil unless self.save
      
      child[parent_column] = self.id
      child[left_col_name] = 2
      child[right_col_name]= 3
      return child.save
    else
      # OK, we need to add and shift everything else to the right
      child[parent_column] = self.id
      right_bound = self[right_col_name]
      child[left_col_name] = right_bound
      child[right_col_name] = right_bound + 1
      self[right_col_name] += 2
      self.class.base_class.transaction {
        self.class.base_class.update_all( "#{left_col_name} = (#{left_col_name} + 2)",  "#{scope_condition} AND #{left_col_name} >= #{right_bound}" )
        self.class.base_class.update_all( "#{right_col_name} = (#{right_col_name} + 2)",  "#{scope_condition} AND #{right_col_name} >= #{right_bound}" )
        self.save
        child.save
      }
    end
  end                                   
end

#all_children ⇒ Object

Returns a set of all of its children and nested children



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# File 'lib/active_record/acts/nested_set.rb', line 187

def all_children
  self.class.base_class.find(:all, :conditions => "#{scope_condition} AND (#{left_col_name} > #{self[left_col_name]}) and (#{right_col_name} < #{self[right_col_name]})" )
end

#before_destroy ⇒ Object

Prunes a branch off of the tree, shifting all of the elements on the right back to the left so the counts still work.



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# File 'lib/active_record/acts/nested_set.rb', line 198

def before_destroy
  return if self[right_col_name].nil? || self[left_col_name].nil?
  dif = self[right_col_name] - self[left_col_name] + 1

  self.class.base_class.transaction {
    self.class.base_class.delete_all( "#{scope_condition} and #{left_col_name} > #{self[left_col_name]} and #{right_col_name} < #{self[right_col_name]}" )
    self.class.base_class.update_all( "#{left_col_name} = (#{left_col_name} - #{dif})",  "#{scope_condition} AND #{left_col_name} >= #{self[right_col_name]}" )
    self.class.base_class.update_all( "#{right_col_name} = (#{right_col_name} - #{dif} )",  "#{scope_condition} AND #{right_col_name} >= #{self[right_col_name]}" )
  }
end

#child? ⇒ Boolean

Returns true is this is a child node

Returns:

  • (Boolean) 


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# File 'lib/active_record/acts/nested_set.rb', line 125

def child?                          
  parent_id = self[parent_column]
  !(parent_id == 0 || parent_id.nil?) && (self[left_col_name] > 1) && (self[right_col_name] > self[left_col_name])
end

#children_count ⇒ Object

Returns the number of nested children of this object.



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# File 'lib/active_record/acts/nested_set.rb', line 177

def children_count
  return (self[right_col_name] - self[left_col_name] - 1)/2
end

#direct_children ⇒ Object

Returns a set of only this entry’s immediate children



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# File 'lib/active_record/acts/nested_set.rb', line 192

def direct_children
  self.class.base_class.find(:all, :conditions => "#{scope_condition} and #{parent_column} = #{self.id}")
end

#full_set ⇒ Object

Returns a set of itself and all of its nested children



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# File 'lib/active_record/acts/nested_set.rb', line 182

def full_set
  self.class.base_class.find(:all, :conditions => "#{scope_condition} AND (#{left_col_name} BETWEEN #{self[left_col_name]} and #{self[right_col_name]})" )
end

#root? ⇒ Boolean

Returns true is this is a root node.

Returns:

  • (Boolean) 


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# File 'lib/active_record/acts/nested_set.rb', line 119

def root?
  parent_id = self[parent_column]
  (parent_id == 0 || parent_id.nil?) && (self[left_col_name] == 1) && (self[right_col_name] > self[left_col_name])
end

#unknown? ⇒ Boolean

Returns true if we have no idea what this is

Returns:

  • (Boolean) 


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# File 'lib/active_record/acts/nested_set.rb', line 131

def unknown?
  !root? && !child?
end