Module | ActiveRecord::Acts::List::ClassMethods |
In: |
vendor/rails/activerecord/lib/active_record/acts/list.rb
|
This act provides the capabilities for sorting and reordering a number of objects in a list. The class that has this specified needs to have a "position" column defined as an integer on the mapped database table.
Todo list example:
class TodoList < ActiveRecord::Base has_many :todo_items, :order => "position" end class TodoItem < ActiveRecord::Base belongs_to :todo_list acts_as_list :scope => :todo_list end todo_list.first.move_to_bottom todo_list.last.move_higher
Configuration options are:
# File vendor/rails/activerecord/lib/active_record/acts/list.rb, line 34 34: def acts_as_list(options = {}) 35: configuration = { :column => "position", :scope => "1 = 1" } 36: configuration.update(options) if options.is_a?(Hash) 37: 38: configuration[:scope] = "#{configuration[:scope]}_id".intern if configuration[:scope].is_a?(Symbol) && configuration[:scope].to_s !~ /_id$/ 39: 40: if configuration[:scope].is_a?(Symbol) 41: scope_condition_method = %( 42: def scope_condition 43: if #{configuration[:scope].to_s}.nil? 44: "#{configuration[:scope].to_s} IS NULL" 45: else 46: "#{configuration[:scope].to_s} = \#{#{configuration[:scope].to_s}}" 47: end 48: end 49: ) 50: else 51: scope_condition_method = "def scope_condition() \"#{configuration[:scope]}\" end" 52: end 53: 54: class_eval "include ActiveRecord::Acts::List::InstanceMethods\n\ndef acts_as_list_class\n::\#{self.name}\nend\n\ndef position_column\n'\#{configuration[:column]}'\nend\n\n\#{scope_condition_method}\n\nafter_destroy :remove_from_list\nbefore_create :add_to_list_bottom\n" 55: end