angular应用，一个input上有自定义directive和ng-model，怎么在directive更新input的value时更新model

https://segmentfault.com/q/1010000000347476

wise.directive('upload', function ($parse) {
return {
link: function ($scope, iElement, iAttrs, controller) {
iElement.upload({
success: function(data, self) {
$parse(iAttrs['ngModel']).assign($scope, data);
$scope.$apply();
},
});
}
};
});