Module: OpenStax::Utilities::ActsAsNumberable

Included in:
ActiveRecord::Base
Defined in:
lib/openstax/utilities/acts_as_numberable.rb

Defined Under Namespace

Modules: BasicInstanceMethods, ContainerInstanceMethods

Instance Method Summary collapse

Instance Method Details

#acts_as_numberable(options = {}) ⇒ Object

Adds code to an ActiveRecord object so that it can be sorted.

Examples:

Model is ordered globally using a ‘number’ field

class MyModel < ActiveRecord::Base
  acts_as_numberable

Model is ordered globally using a ‘position’ field

class MyModel < ActiveRecord::Base
  acts_as_numberable :number_field => :position

Model is ordered within a container class using a position field

class MyModel < ActiveRecord::Base
  belongs_to :other_model
  acts_as_numberable :container => :other_model,
                     :number_field => :position

Parameters:

  • :container —

    The relationship that contains this model in an order. Note that this code assumes the foreign key for this container is found by appending “_id” onto the container name, which might not always be the case.

  • :number_field —

    The column to use as the sorting number, given either as a string or a symbol. The default is ‘number’

  • :table_class —

    By default this code assumes that the database table name to use for this model can be derived from the model’s class name; in some cases (e.g. STI) this is not the case and this parameter can be used to manually specify the class from which to derive the database table name.



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# File 'lib/openstax/utilities/acts_as_numberable.rb', line 32

def acts_as_numberable(options={})
  configuration = {}
  configuration.update(options) if options.is_a?(Hash)
 
  container_column = nil
  container_column_symbol = nil

  # When calling assign_number below, you normally want to run a query against
  # self.class to figure out what the next available number is; however, if the 
  # class acting as numberable is using STI, self.class will return the child class
  # which is likely not what we want.  In these cases, we can specify the base
  # class here (the class that has the same name as the DB table) so that it is used
  # instead.
  table_class = configuration[:table_class]

  number_field = (configuration[:number_field] || 'number').to_s
  
  if !configuration[:container].nil?
    container_column = configuration[:container].to_s + "_id"
    container_column_symbol = configuration[:container].to_sym
  end
  
  uniqueness_scope_string = container_column.nil? ? "" : ":scope => :#{container_column},"
 
  class_eval <<-EOV
    include ActsAsNumberable::BasicInstanceMethods
  
    before_validation :assign_number, :on => :create
    
    validates :#{number_field}, :uniqueness => { #{uniqueness_scope_string}
                                                 :allow_nil => true},
                                :numericality => { :only_integer => true, 
                                                   :greater_than_or_equal_to => 0,
                                                   :allow_nil => true }    

    
    after_destroy :mark_as_destroyed
    
    attr_accessor :destroyed
    attr_accessor :changed_sets

    attr_protected :#{number_field}
  
    scope :ordered, order('#{number_field} ASC')
    scope :reverse_ordered, order('#{number_field} DESC')
    
    def self.sort!(sorted_ids)
      return if sorted_ids.blank?
      items = []
      ActiveRecord::Base.transaction do
        items = find_in_specified_order(sorted_ids)
        
        items.each do |item|
          item.send('#{number_field}=', nil)
          item.save!
        end
        
        items.each_with_index do |item, ii| 
          item.send('#{number_field}=', ii)
          item.save!
        end
      end
      items
    end

    def table_class
      #{table_class}
    end

    def number_field
      '#{number_field}'
    end
  EOV
 
 
  if !configuration[:container].nil?
    class_eval <<-EOV
      include ActsAsNumberable::ContainerInstanceMethods
    
      # When we had nested acts_as_numberables, there were cases where the
      # objects were having their numbers changed (as their peers were being
      # removed from the container), but then when it came time to delete those 
      # objects they still had their old number.  So just reload before
      # destroy.
      before_destroy(prepend: true) {self.reload}
    
      after_destroy :remove_from_container!
    
      def container_column
        '#{container_column}'
      end

      def container
        '#{configuration[:container]}'
      end

      def table_class
        #{table_class}
      end
    
    EOV
    
  end
     
end