Module: SymetrieCom::Acts::NestedSet::ClassMethods

Defined in:
lib/better_nested_set.rb

Overview

This module provides an enhanced acts_as_nested_set mixin for ActiveRecord. Please see the README for background information, examples, and tips on usage.

Defined Under Namespace

Modules: SingletonMethods

Instance Method Summary collapse

Instance Method Details

#acts_as_nested_set(options = {}) ⇒ Object

Configuration options are:

  • dependent - behaviour for cascading destroy operations (default: :delete_all)

  • parent_column - Column name for the parent/child foreign key (default: parent_id).

  • left_column - Column name for the left index (default: lft).

  • right_column - Column name for the right index (default: rgt). NOTE: Don’t use left and right, since these are reserved database words.

  • scope - Restricts what is to be considered a tree. Given a symbol, it’ll attach “_id” (if it isn’t there already) and use that as the foreign key restriction. It’s also possible to give it an entire string that is interpolated if you need a tighter scope than just a foreign key. Example: acts_as_nested_set :scope => 'tree_id = #{tree_id} AND completed = 0'

  • text_column - Column name for the title field (optional). Used as default in the your-class_options_for_select helper method. If empty, will use the first string field of your model class.



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# File 'lib/better_nested_set.rb', line 24

def acts_as_nested_set(options = {})          
  
  extend(SingletonMethods) unless respond_to?(:find_in_nestedset)
  
  options[:scope] = "#{options[:scope]}_id".intern if options[:scope].is_a?(Symbol) && options[:scope].to_s !~ /_id$/
  
  write_inheritable_attribute(:acts_as_nested_set_options,
     { :parent_column  => (options[:parent_column] || 'parent_id'),
       :left_column    => (options[:left_column]   || 'lft'),
       :right_column   => (options[:right_column]  || 'rgt'),
       :scope          => (options[:scope] || '1 = 1'),
       :text_column    => (options[:text_column] || columns.collect{|c| (c.type == :string) ? c.name : nil }.compact.first),
       :class          => self, # for single-table inheritance
       :dependent      => (options[:dependent] || :delete_all) # accepts :delete_all and :destroy
      } )
  
  class_inheritable_reader :acts_as_nested_set_options
  
  base_set_class.class_inheritable_accessor :acts_as_nested_set_scope_enabled
  base_set_class.acts_as_nested_set_scope_enabled = true
  
  if acts_as_nested_set_options[:scope].is_a?(Symbol)
    scope_condition_method = %(
      def scope_condition
        if #{acts_as_nested_set_options[:scope].to_s}.nil?
          self.class.use_scope_condition? ? "#{table_name}.#{acts_as_nested_set_options[:scope].to_s} IS NULL" : "(1 = 1)"
        else
          self.class.use_scope_condition? ? "#{table_name}.#{acts_as_nested_set_options[:scope].to_s} = \#{#{acts_as_nested_set_options[:scope].to_s}}" : "(1 = 1)"
        end
      end
    )
  else
    scope_condition_method = "def scope_condition(); self.class.use_scope_condition? ? \"#{acts_as_nested_set_options[:scope]}\" : \"(1 = 1)\"; end"
  end
  
  # skip recursive destroy calls
  attr_accessor  :skip_before_destroy
  
  # no bulk assignment
  attr_protected  acts_as_nested_set_options[:left_column].intern,
                  acts_as_nested_set_options[:right_column].intern,
                  acts_as_nested_set_options[:parent_column].intern
  # no assignment to structure fields
  class_eval <<-EOV
    before_create :set_left_right
    before_destroy :destroy_descendants
    include SymetrieCom::Acts::NestedSet::InstanceMethods
  
    def #{acts_as_nested_set_options[:left_column]}=(x)
      raise ActiveRecord::ActiveRecordError, "Unauthorized assignment to #{acts_as_nested_set_options[:left_column]}: it's an internal field handled by acts_as_nested_set code, use move_to_* methods instead."
    end
    def #{acts_as_nested_set_options[:right_column]}=(x)
      raise ActiveRecord::ActiveRecordError, "Unauthorized assignment to #{acts_as_nested_set_options[:right_column]}: it's an internal field handled by acts_as_nested_set code, use move_to_* methods instead."
    end
    def #{acts_as_nested_set_options[:parent_column]}=(x)
      raise ActiveRecord::ActiveRecordError, "Unauthorized assignment to #{acts_as_nested_set_options[:parent_column]}: it's an internal field handled by acts_as_nested_set code, use move_to_* methods instead."
    end
    #{scope_condition_method}
  EOV
end