app/assets/javascripts/admin/directives/track_product.js.coffee
angular.module("ofn.admin").directive "ofnTrackProduct", ["DirtyProducts", (DirtyProducts) ->
require: "ngModel"
link: (scope, element, attrs, ngModel) ->
ngModel.$parsers.push (viewValue) ->
if ngModel.$dirty
DirtyProducts.addProductProperty scope.product.id, attrs.ofnTrackProduct, viewValue
scope.displayDirtyProducts()
viewValue
]