Update ng-model using custom-directive

custom-directive.js

.directive('noNegativeValue',function(){
    //Custom Directive for checking negative value
	
    return {
        restrict: 'A',
        require: '?ngModel',
        link: function(scope, element , attrs, ngModel){
            scope.$watch(attrs.ngModel, function(val){
                if(val < 0){
                  ngModel.$setViewValue('0');
                  ngModel.$render();
                }
            });
        }
    }

})