How to access arguments in a directive?

Question

How to access arguments in a directive?

I've defined a directive like so:

angular.module('MyModule', [])
    .directive('datePicker', function($filter) {
        return {
            require: 'ngModel',
            link: function(scope, elem, attrs, ctrl) {
                ctrl.$formatters.unshift(function(modelValue) {
                    console.log('formatting',modelValue,scope,elem,attrs,ctrl);
                    return $filter('date')(modelValue, 'MM/dd/yyyy');
                });
                ctrl.$parsers.unshift(function(viewValue) {
                    console.log('parsing',viewValue);
                    var date = new Date(viewValue);
                    return isNaN(date) ? '' : date;
                });
            }
        }
    });

Which I apply to an element like so:

<input type="text" date-picker="MM/dd/yyyy" ng-model="clientForm.birthDate" />

My directive gets triggered whenever I add the date-picker attribute to an element, but I want to know how to access the attribute's value (MM/dd/yyyy) inside my directive JS so that I can remove that constant beside $filter. I'm not sure if any of the variables I have access to provide this.

angularjs

Answer 1

Just pull it directly from the attrs:

return $filter('date')(modelValue, attrs.datePicker);

BTW, if the only filter you're using is date, then you can inject that directly:

.directive('datePicker', function (dateFilter) {
    // Keep all your code, just update this line:
    return dateFilter(modelValue, attrs.datePicker || 'MM/dd/yyyy');
    // etc.
}

Answer 2

You can access it from attrs argument of link function.

Demo: http://plnkr.co/edit/DBs4jX9alyCZXt3LaLnF?p=preview

angModule.directive('moDateInput', function ($window) {
    return {
        require:'^ngModel',
        restrict:'A',
        link:function (scope, elm, attrs, ctrl) {
            var moment = $window.moment;
            var dateFormat = attrs.moMediumDate;
            attrs.$observe('moDateInput', function (newValue) {
                if (dateFormat == newValue || !ctrl.$modelValue) return;
                dateFormat = newValue;
                ctrl.$modelValue = new Date(ctrl.$setViewValue);
            });

            ctrl.$formatters.unshift(function (modelValue) {
                scope = scope;
                if (!dateFormat || !modelValue) return "";
                var retVal = moment(modelValue).format(dateFormat);
                return retVal;
            });

            ctrl.$parsers.unshift(function (viewValue) {
                scope = scope;
                var date = moment(viewValue, dateFormat);
                return (date && date.isValid() && date.year() > 1950 ) ? date.toDate() : "";
            });
        }
    };
});