ngModelのFormattersとParsersの使い方

/**

 * inputの値をcurrencyCodeを元にフォーマットする

 *

 * usage:

 *  <input type="text" amount-format="currencyCode">

 */

context.app.directive("amountFormat", function ($parse:ng.IParseService) {

    return {

        restrict: 'A',

        require: 'ngModel',

        link: function (scope:ng.IScope, element:ng.IAugmentedJQuery, attrs:ng.IAttributes, ngModel:ng.INgModelController) {

            var currencyCode = $parse(attrs["amountFormat"])(scope);

            var currencyInfo =  Currency.getInformationByCode(currencyCode);

            var offset = currencyInfo.map((x)=>x.offset).getOrElse(1);


            // model から view へ

            ngModel.$formatters.push(function toView(amount) {

                if(_.isUndefined(amount)) {

                    return NaN;

                }

                return parseFloat((amount / offset).toFixed((offset == 100) ? 2 : 0));

            });

            // view から model へ

            ngModel.$parsers.push(function(amount) {

                return (amount * offset).toFixed(0);

            });

        }

    };

});