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 vendor/rails/activerecord/lib/active_record/acts/nested_set.rb, line 142 142: def add_child( child ) 143: self.reload 144: child.reload 145: 146: if child.root? 147: raise "Adding sub-tree isn\'t currently supported" 148: else 149: if ( (self[left_col_name] == nil) || (self[right_col_name] == nil) ) 150: # Looks like we're now the root node! Woo 151: self[left_col_name] = 1 152: self[right_col_name] = 4 153: 154: # What do to do about validation? 155: return nil unless self.save 156: 157: child[parent_column] = self.id 158: child[left_col_name] = 2 159: child[right_col_name]= 3 160: return child.save 161: else 162: # OK, we need to add and shift everything else to the right 163: child[parent_column] = self.id 164: right_bound = self[right_col_name] 165: child[left_col_name] = right_bound 166: child[right_col_name] = right_bound + 1 167: self[right_col_name] += 2 168: self.class.transaction { 169: self.class.update_all( "#{left_col_name} = (#{left_col_name} + 2)", "#{scope_condition} AND #{left_col_name} >= #{right_bound}" ) 170: self.class.update_all( "#{right_col_name} = (#{right_col_name} + 2)", "#{scope_condition} AND #{right_col_name} >= #{right_bound}" ) 171: self.save 172: child.save 173: } 174: end 175: end 176: end
Returns a set of all of its children and nested children
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# File vendor/rails/activerecord/lib/active_record/acts/nested_set.rb, line 189 189: def all_children 190: self.class.find(:all, :conditions => "#{scope_condition} AND (#{left_col_name} > #{self[left_col_name]}) and (#{right_col_name} < #{self[right_col_name]})" ) 191: end
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 vendor/rails/activerecord/lib/active_record/acts/nested_set.rb, line 200 200: def before_destroy 201: return if self[right_col_name].nil? || self[left_col_name].nil? 202: dif = self[right_col_name] - self[left_col_name] + 1 203: 204: self.class.transaction { 205: self.class.delete_all( "#{scope_condition} and #{left_col_name} > #{self[left_col_name]} and #{right_col_name} < #{self[right_col_name]}" ) 206: self.class.update_all( "#{left_col_name} = (#{left_col_name} - #{dif})", "#{scope_condition} AND #{left_col_name} >= #{self[right_col_name]}" ) 207: self.class.update_all( "#{right_col_name} = (#{right_col_name} - #{dif} )", "#{scope_condition} AND #{right_col_name} >= #{self[right_col_name]}" ) 208: } 209: end
Returns true is this is a child node
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# File vendor/rails/activerecord/lib/active_record/acts/nested_set.rb, line 127 127: def child? 128: parent_id = self[parent_column] 129: !(parent_id == 0 || parent_id.nil?) && (self[left_col_name] > 1) && (self[right_col_name] > self[left_col_name]) 130: end
Returns the number of nested children of this object.
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# File vendor/rails/activerecord/lib/active_record/acts/nested_set.rb, line 179 179: def children_count 180: return (self[right_col_name] - self[left_col_name] - 1)/2 181: end
Returns a set of only this entry’s immediate children
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# File vendor/rails/activerecord/lib/active_record/acts/nested_set.rb, line 194 194: def direct_children 195: self.class.find(:all, :conditions => "#{scope_condition} and #{parent_column} = #{self.id}") 196: end
Returns a set of itself and all of its nested children
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# File vendor/rails/activerecord/lib/active_record/acts/nested_set.rb, line 184 184: def full_set 185: self.class.find(:all, :conditions => "#{scope_condition} AND (#{left_col_name} BETWEEN #{self[left_col_name]} and #{self[right_col_name]})" ) 186: end
Returns true is this is a root node.
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# File vendor/rails/activerecord/lib/active_record/acts/nested_set.rb, line 121 121: def root? 122: parent_id = self[parent_column] 123: (parent_id == 0 || parent_id.nil?) && (self[left_col_name] == 1) && (self[right_col_name] > self[left_col_name]) 124: end
Returns true if we have no idea what this is
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# File vendor/rails/activerecord/lib/active_record/acts/nested_set.rb, line 133 133: def unknown? 134: !root? && !child? 135: end