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

Decrease the position of this item without adjusting the rest of the list.



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# File 'lib/active_record/acts/list.rb', line 137

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

#first? ⇒ Boolean

Return true if this object is the first in the list.

Returns:

  • (Boolean) 


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

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

#higher_item ⇒ Object

Return the next higher item in the list.



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# File 'lib/active_record/acts/list.rb', line 155

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

#in_list? ⇒ Boolean

Test if this record is in a list

Returns:

  • (Boolean) 


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# File 'lib/active_record/acts/list.rb', line 171

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

#increment_position ⇒ Object

Increase the position of this item without adjusting the rest of the list.



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

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

#insert_at(position = 1) ⇒ Object

Insert the item at the given position (defaults to the top position of 1).



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

def insert_at(position = 1)
  insert_at_position(position)
end

#last? ⇒ Boolean

Return true if this object is the last in the list.

Returns:

  • (Boolean) 


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# File 'lib/active_record/acts/list.rb', line 149

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

#lower_item ⇒ Object

Return the next lower item in the list.



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# File 'lib/active_record/acts/list.rb', line 163

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

#move_higher ⇒ Object

Swap positions with the next higher item, if one exists.



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# File 'lib/active_record/acts/list.rb', line 93

def move_higher
  return unless higher_item

  acts_as_list_class.transaction do
    higher_item.increment_position
    decrement_position
  end
end

#move_lower ⇒ Object

Swap positions with the next lower item, if one exists.



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# File 'lib/active_record/acts/list.rb', line 83

def move_lower
  return unless lower_item

  acts_as_list_class.transaction do
    lower_item.decrement_position
    increment_position
  end
end

#move_to_bottom ⇒ Object

Move to the bottom of the list. If the item is already in the list, the items below it have their position adjusted accordingly.



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

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

#move_to_top ⇒ Object

Move to the top of the list. If the item is already in the list, the items above it have their position adjusted accordingly.



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# File 'lib/active_record/acts/list.rb', line 114

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

#remove_from_list ⇒ Object

Removes the item from the list.



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# File 'lib/active_record/acts/list.rb', line 123

def remove_from_list
  if in_list?
    decrement_positions_on_lower_items
    update_attribute position_column, nil
  end
end