Module: ActiveRecord::Acts::List::InstanceMethods

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

Overview

All the methods available to a record that has had acts_as_list specified. Each method works by assuming the object to be the item in the list, so chapter.move_lower would move that chapter lower in the list of all chapters. Likewise, chapter.first? would return true if that chapter is the first in the list of all chapters.

Instance Method Summary collapse

Instance Method Details

#decrement_position ⇒ Object 



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# File 'lib/active_record/acts/list.rb', line 121

def decrement_position
  return unless in_list?
  update_attribute position_column, self.send(position_column).to_i - 1
end

#first? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/acts/list.rb', line 126

def first?
  return false unless in_list?
  self.send(position_column) == 1
end

#higher_item ⇒ Object 



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# File 'lib/active_record/acts/list.rb', line 136

def higher_item
  return nil unless in_list?
  self.class.find(:first, :conditions =>
    "#{scope_condition} AND #{position_column} = #{(send(position_column).to_i - 1).to_s}"
  )
end

#in_list? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/acts/list.rb', line 150

def in_list?
  !send(position_column).nil?
end

#increment_position ⇒ Object 



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# File 'lib/active_record/acts/list.rb', line 116

def increment_position
  return unless in_list?
  update_attribute position_column, self.send(position_column).to_i + 1
end

#insert_at(position = 1) ⇒ Object 



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# File 'lib/active_record/acts/list.rb', line 74

def insert_at(position = 1)
  position == 1 ? add_to_list_top : insert_at_position(position)
end

#last? ⇒ Boolean

Returns:

  • (Boolean) 


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

def last?
  return false unless in_list?
  self.send(position_column) == bottom_position_in_list
end

#lower_item ⇒ Object 



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# File 'lib/active_record/acts/list.rb', line 143

def lower_item
  return nil unless in_list?
  self.class.find(:first, :conditions =>
    "#{scope_condition} AND #{position_column} = #{(send(position_column).to_i + 1).to_s}"
  )
end

#move_higher ⇒ Object 



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# File 'lib/active_record/acts/list.rb', line 87

def move_higher
  return unless higher_item

  self.class.transaction do
    higher_item.increment_position
    decrement_position
  end
end

#move_lower ⇒ Object 



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# File 'lib/active_record/acts/list.rb', line 78

def move_lower
  return unless lower_item

  self.class.transaction do
    lower_item.decrement_position
    increment_position
  end
end

#move_to_bottom ⇒ Object 



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# File 'lib/active_record/acts/list.rb', line 96

def move_to_bottom
  return unless in_list?
  self.class.transaction do
    decrement_positions_on_lower_items
    assume_bottom_position
  end
end

#move_to_top ⇒ Object 



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# File 'lib/active_record/acts/list.rb', line 104

def move_to_top
  return unless in_list?
  self.class.transaction do
    increment_positions_on_higher_items
    assume_top_position
  end
end

#remove_from_list ⇒ Object 



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# File 'lib/active_record/acts/list.rb', line 112

def remove_from_list
  decrement_positions_on_lower_items if in_list?
end