Module: Positionable::InstanceMethods

Defined in:
lib/positionable.rb

Overview

All the methods available to a record that has had acts_as_positionable 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

#first?(list_name = :default) ⇒ Boolean

True if the record is the first in the list.

Returns:

  • (Boolean) 


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# File 'lib/positionable.rb', line 167

def first?(list_name = :default)
  in_list? && list_position == top_position_in_list(list_name)
end

#higher_item(list_name = :default) ⇒ Object Also known as: previous_item

Returns the next higher item in the list.



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# File 'lib/positionable.rb', line 177

def higher_item(list_name = :default)
  return nil unless in_list?
  scoped(list_name).descending(list_name).first(:conditions => options_for_position(list_name, '<'))
end

#in_list?(list_name = :default) ⇒ Boolean

True if the record is in the list.

Returns:

  • (Boolean) 


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# File 'lib/positionable.rb', line 191

def in_list?(list_name = :default)
  !list_position(list_name).nil?
end

#insert_at(position = :top, list_name = :default) ⇒ Object

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



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# File 'lib/positionable.rb', line 125

def insert_at(position = :top, list_name = :default)
  if !position.is_a?(Symbol) && position <= 0
    position = :top
  elsif !position.is_a?(Symbol) && position > bottom_position_in_list(list_name) && position != 1
    position = :bottom
  end
  insert_at_position(list_name, position)
end

#insert_at_bottom(list_name = :default) ⇒ Object 



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# File 'lib/positionable.rb', line 138

def insert_at_bottom(list_name = :default)
  insert_at_position(list_name, :bottom)
end

#insert_at_top(list_name = :default) ⇒ Object 



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# File 'lib/positionable.rb', line 134

def insert_at_top(list_name = :default)
  insert_at_position(list_name, :top)
end

#last?(list_name = :default) ⇒ Boolean

True if the record is the last in the list.

Returns:

  • (Boolean) 


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# File 'lib/positionable.rb', line 172

def last?(list_name = :default)
  in_list? && list_position == bottom_position_in_list(list_name)
end

#list_position(list_name = :default) ⇒ Object

Returns the record list position for the list.



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# File 'lib/positionable.rb', line 196

def list_position(list_name = :default)
  send position_column(list_name)
end

#lower_item(list_name = :default) ⇒ Object Also known as: next_item

Returns the next lower item in the list.



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# File 'lib/positionable.rb', line 184

def lower_item(list_name = :default)
  return nil unless in_list?
  scoped(list_name).ascending(list_name).first(:conditions => options_for_position(list_name, '>'))
end

#move_higher(list_name = :default) ⇒ Object Also known as: move_up

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



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# File 'lib/positionable.rb', line 150

def move_higher(list_name = :default)
  higher = higher_item
  insert_at_position(list_name, higher.list_position) if higher
end

#move_lower(list_name = :default) ⇒ Object Also known as: move_down

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



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# File 'lib/positionable.rb', line 143

def move_lower(list_name = :default)
  lower = lower_item
  insert_at_position(list_name, lower.list_position) if lower
end

#move_to_bottom(list_name = :default) ⇒ Object

Move to the bottom of the list.



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

def move_to_bottom(list_name = :default)
  insert_at_position(list_name, :bottom) if in_list?
end

#move_to_top(list_name = :default) ⇒ Object

Move to the top of the list.



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# File 'lib/positionable.rb', line 162

def move_to_top(list_name = :default)
  insert_at_position(list_name, :top) if in_list?
end

#remove_from_list(list_name = :default) ⇒ Object

Removes the record from the list and shift other items accordingly.



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# File 'lib/positionable.rb', line 201

def remove_from_list(list_name = :default)
  if in_list?
    acts_as_positionable_class.transaction do
      decrement_positions_on_lower_items(list_name)
      update_attribute position_column(list_name), nil
    end
  end
end