Angular元素指令如何获取属性值

Question

I'm using an Angular element directive to generate an amount of stars (rating) for a given item.

I create a directive called 'generateStars' and I am using it like so in the view.

<generate-stars amount="3"></generate-stars>

I don't want the directive to be dependant on the current scope so I was wondering if I could take in the "amount" attribute and get the value within my directive function.

Here is that function:

angular.module('myapp.directives', [])

.directive('generateStars', function() {
    var html = '<i class="fa fa-star"></i>';

    return {
        restrict: 'E',
        template: html,
        replace: true
    };
});

I couldn't find any obvious documentation to allow me to get the value of 'amount' inside my directive function.

Any help would be much appreciated. Thanks.

Answer 1

You could use isolated scope and use amount value can be passed as attribute as you are doing so.

Markup

<generate-stars amount="{{amount}}"></generate-stars>

Controller

$scope.amount = 3; //passing it through the scope.

Directive

angular.module('myapp.directives', [])

.directive('generateStars', function() {
    var html = '<i ng-repeat="i in [1, 2, 3, 4, 5]" class="fa fa-star" ng-if="i>=amount"></i>';

    return {
        restrict: 'E',
        template: html,
        replace: true,
        scope: { 
           amount: '@' //`@` for one way binding.
        }
    };
});

This can be without isolated scope. Basically you need to create class fa-3x in your directive template.

angular.module('myapp.directives', [])

.directive('generateStars', function() {
        return '<i ng-repeat="i in [1, 2, 3, 4, 5]" class="fa fa-star" ng-if="i>='+ attrs.amount +' "></i>'
    };

    return {
        restrict: 'E',
        template: html,
        replace: true
    };
});

Answer 2

You can use attrs object available in your link function of your Directive Definition Object.

angular.module('myapp.directives', [])
.directive('generateStars', function() {
    var html = '<i class="fa fa-star"></i>';

    return {
        restrict: 'E',
        template: html,
        replace: true,
        link: function(scope, element, attrs) {
           /*all attributes passed to directive are available as properties
              on attrs object*/
            console.log(attrs.amount);
        }
    };
});

HTML

<generate-stars amount="3"></generate-stars>

With that, when your directive is rendered, prints the value 3 in console.

Answer 3

I appreciate the help guys but neither of these solutions ended up working out for me. This is what I ended up doing.

angular.module('myApp.directives', [])

.directive('generateStars', function() {
    var html = '<i class="fa fa-star" ng-repeat="n in [] | range:roundedAmount"></i>';

    return {
        restrict: 'E',
        scope: {
            amount: '='
        },
        link: function(scope, element, attrs) {
            scope.roundedAmount = parseInt(scope.amount);
        },
        replace: true,
        template: html
    };
})

.filter('range', function() {
    return function(input, total) {
        total = parseInt(total);
        for (var i=0; i<total; i++)
            input.push(i);

        return input;
    };
});