Mongoid sortable

make element sortable

$(document).ready(function() {
  $('table.tracks tbody').makeSortable({ url: "<%= sort_my_mix_tracks_path(mix) -%>" });
});

make sortable

$.fn.makeSortable = function(options) {
  $(this).sortable({
    axis: 'y',
    dropOnEmpty:false, 
    handle: '.handle', 
    cursor: 'crosshair',
    items: 'tr',
    opacity: 0.4,
    scroll: true,
    update: function(){
      $.ajax({
        type: 'put', 
        data: $('table.tracks tbody').sortable('serialize'), 
        dataType: 'script', 
        url: options.url
      })
    }
  });
}

sort action

  def sort
    tracks = params[:track].collect { |id| mix.tracks.find(id) }
    mix.tracks.clear

    tracks.each { |t| mix.tracks.create(t.attributes) }
  end