HabtmList

This plugin arose out of a page on the Rails wiki: http://wiki.rubyonrails.org/rails/pages/BetterHabtmList

The purpose is to allow position-based "acts_as_list"-like behavior in a has_and_belongs_to_many association. Methods are included to move members up and down in the list.

The original author of the technique, according to the wiki history, was "Matt." Sorry, I don't know his last name; I'll give proper credit if he turns up to take it. I refactored and fixed some bugs in the code, and now I'm simply putting it up on Github. I'm claiming no ownership rights on this code whatsoever; use it any way you like.

Usage

class Category < ActiveRecord::Base has_and_belongs_to_many :products, :order => 'position', :list => true end

Methods

first?(item) - returns true if item is first in the list last?(item) - returns true if item is last in the list in_list?(item) - returns true if item exists in the list higher_item(item) - returns the item one position above the given item in the list lower_item(item) - returns the item one position below the given item in the list move_higher(item) - moves the item up one position in the list move_lower(item) - moves the item down one position in the list move_to_top(item) - moves the item to the first position in the list move_to_bottom(item) - moves the item to the last position in the list add_to_list_top(item) - adds the item to the list in the first position add_to_list_bottom(item) - adds the item to the list in the last position move_to_position(item, position) - moves the item to the stated position in the list reset_positions - "first aid" method to restore list positions if positions become duplicated or go out of sync (e.g., if records are inserted or updated by external methods)

Support

I don't promise any, but if you have any questions or complaints you're welcome to e-mail me at [email protected].

Also check out my podcast, Escape Pod [http://escapepod.org], if you're interested in science fiction short stories.

• Steve Eley