Module: ActsAsList::InstanceMethods

Defined in:
lib/acts_as_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_positionObject

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


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# File 'lib/acts_as_list.rb', line 139

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/acts_as_list.rb', line 145

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

#higher_itemObject

Return the next higher item in the list.


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# File 'lib/acts_as_list.rb', line 157

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

#in_list?Boolean

Test if this record is in a list

Returns:

  • (Boolean)

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# File 'lib/acts_as_list.rb', line 173

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

#increment_positionObject

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


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# File 'lib/acts_as_list.rb', line 133

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/acts_as_list.rb', line 76

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/acts_as_list.rb', line 151

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

#lower_itemObject

Return the next lower item in the list.


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# File 'lib/acts_as_list.rb', line 165

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

#move_higherObject

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


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# File 'lib/acts_as_list.rb', line 91

def move_higher
  higher = higher_item
  return unless higher
  acts_as_list_class.transaction do
    self.update_attribute(position_column, higher.send(position_column))
    higher.increment_position
  end
end

#move_lowerObject

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


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# File 'lib/acts_as_list.rb', line 81

def move_lower
  lower = lower_item
  return unless lower
  acts_as_list_class.transaction do
    self.update_attribute(position_column, lower.send(position_column))
    lower.decrement_position
  end
end

#move_to_bottomObject

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/acts_as_list.rb', line 102

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_topObject

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/acts_as_list.rb', line 112

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(save = true) ⇒ Object

Removes the item from the list.


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# File 'lib/acts_as_list.rb', line 121

def remove_from_list(save = true)
  if in_list?
    decrement_positions_on_lower_items
    update_attribute(position_column, nil) if save
  end
end

#remove_from_list_without_savingObject


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# File 'lib/acts_as_list.rb', line 128

def remove_from_list_without_saving
  self.remove_from_list(false)
end