将AngularJS范围变量从指令传递给控制器​​的最简单方法？

时间：2012-11-10 02:42:41

标签： angularjs angularjs-directive ng-controller

将AngularJS范围变量从指令传递给控制器​​的最简单方法是什么？我见过的所有例子看起来都很复杂，是不是我可以从指令访问控制器，并设置其中一个范围变量？

2 个答案:

答案 0 :(得分：149)

于2014/8/25编辑： Here是我分叉的地方。

谢谢@anvarik。

这是JSFiddle。我忘记了分叉的地方。但这是一个很好的例子，显示了=和@

之间的区别 
<div ng-controller="MyCtrl">
    <h2>Parent Scope</h2>
    <input ng-model="foo"> <i>// Update to see how parent scope interacts with component scope</i>    
    <br><br>
    <!-- attribute-foo binds to a DOM attribute which is always
    a string. That is why we are wrapping it in curly braces so
    that it can be interpolated. -->
    <my-component attribute-foo="{{foo}}" binding-foo="foo"
        isolated-expression-foo="updateFoo(newFoo)" >
        <h2>Attribute</h2>
        <div>
            <strong>get:</strong> {{isolatedAttributeFoo}}
        </div>
        <div>
            <strong>set:</strong> <input ng-model="isolatedAttributeFoo">
            <i>// This does not update the parent scope.</i>
        </div>
        <h2>Binding</h2>
        <div>
            <strong>get:</strong> {{isolatedBindingFoo}}
        </div>
        <div>
            <strong>set:</strong> <input ng-model="isolatedBindingFoo">
            <i>// This does update the parent scope.</i>
        </div>
        <h2>Expression</h2>    
        <div>
            <input ng-model="isolatedFoo">
            <button class="btn" ng-click="isolatedExpressionFoo({newFoo:isolatedFoo})">Submit</button>
            <i>// And this calls a function on the parent scope.</i>
        </div>
    </my-component>
</div>

var myModule = angular.module('myModule', [])
    .directive('myComponent', function () {
        return {
            restrict:'E',
            scope:{
                /* NOTE: Normally I would set my attributes and bindings
                to be the same name but I wanted to delineate between
                parent and isolated scope. */                
                isolatedAttributeFoo:'@attributeFoo',
                isolatedBindingFoo:'=bindingFoo',
                isolatedExpressionFoo:'&'
            }        
        };
    })
    .controller('MyCtrl', ['$scope', function ($scope) {
        $scope.foo = 'Hello!';
        $scope.updateFoo = function (newFoo) {
            $scope.foo = newFoo;
        }
    }]);

答案 1 :(得分：69)

等到angular已经评估了变量

我有很多摆弄这个问题，即使在范围内使用"="定义的变量也无法使其工作。根据您的具体情况，这里有三种解决方案。

解决方案＃1

我发现在传递给指令时，变量没有按角度进行评估。这意味着您可以访问它并在模板中使用它，但不能在链接或app控制器功能中使用它，除非我们等待它被评估。

如果变量正在更改，或者是通过请求提取，则应使用$observe或$watch：

app.directive('yourDirective', function () {
    return {
        restrict: 'A',
        // NB: no isolated scope!!
        link: function (scope, element, attrs) {
            // observe changes in attribute - could also be scope.$watch
            attrs.$observe('yourDirective', function (value) {
                if (value) {
                    console.log(value);
                    // pass value to app controller
                    scope.variable = value;
                }
            });
        },
        // the variable is available in directive controller,
        // and can be fetched as done in link function
        controller: ['$scope', '$element', '$attrs',
            function ($scope, $element, $attrs) {
                // observe changes in attribute - could also be scope.$watch
                $attrs.$observe('yourDirective', function (value) {
                    if (value) {
                        console.log(value);
                        // pass value to app controller
                        $scope.variable = value;
                    }
                });
            }
        ]
    };
})
.controller('MyCtrl', ['$scope', function ($scope) {
    // variable passed to app controller
    $scope.$watch('variable', function (value) {
        if (value) {
            console.log(value);
        }
    });
}]);

这是html（记住括号！）：

<div ng-controller="MyCtrl">
    <div your-directive="{{ someObject.someVariable }}"></div>
    <!-- use ng-bind in stead of {{ }}, when you can to avoids FOUC -->
    <div ng-bind="variable"></div>
</div>

请注意，如果使用$observe函数，则不应将范围中的变量设置为"="。此外，我发现它将对象作为字符串传递，因此如果您传递对象，请使用解决方案＃2 或scope.$watch(attrs.yourDirective, fn)（或＃3 ，如果您的变量没有改变。）

解决方案＃2

如果您的变量是在例如另一个控制器，但只需等到angular对它进行评估，然后再将其发送到app控制器，我们可以使用$timeout等待$apply运行。此外，我们需要使用$emit将其发送到父作用域app控制器（由于指令中的隔离范围）：

app.directive('yourDirective', ['$timeout', function ($timeout) {
    return {
        restrict: 'A',
        // NB: isolated scope!!
        scope: {
            yourDirective: '='
        },
        link: function (scope, element, attrs) {
            // wait until after $apply
            $timeout(function(){
                console.log(scope.yourDirective);
                // use scope.$emit to pass it to controller
                scope.$emit('notification', scope.yourDirective);
            });
        },
        // the variable is available in directive controller,
        // and can be fetched as done in link function
        controller: [ '$scope', function ($scope) {
            // wait until after $apply
            $timeout(function(){
                console.log($scope.yourDirective);
                // use $scope.$emit to pass it to controller
                $scope.$emit('notification', scope.yourDirective);
            });
        }]
    };
}])
.controller('MyCtrl', ['$scope', function ($scope) {
    // variable passed to app controller
    $scope.$on('notification', function (evt, value) {
        console.log(value);
        $scope.variable = value;
    });
}]);

这是html（没有括号！）：

<div ng-controller="MyCtrl">
    <div your-directive="someObject.someVariable"></div>
    <!-- use ng-bind in stead of {{ }}, when you can to avoids FOUC -->
    <div ng-bind="variable"></div>
</div>

解决方案＃3

如果变量未更改，并且您需要在指令中对其进行评估，则可以使用$eval函数：

app.directive('yourDirective', function () {
    return {
        restrict: 'A',
        // NB: no isolated scope!!
        link: function (scope, element, attrs) {
            // executes the expression on the current scope returning the result
            // and adds it to the scope
            scope.variable = scope.$eval(attrs.yourDirective);
            console.log(scope.variable);

        },
        // the variable is available in directive controller,
        // and can be fetched as done in link function
        controller: ['$scope', '$element', '$attrs',
            function ($scope, $element, $attrs) {
                // executes the expression on the current scope returning the result
                // and adds it to the scope
                scope.variable = scope.$eval($attrs.yourDirective);
                console.log($scope.variable);
            }
         ]
    };
})
.controller('MyCtrl', ['$scope', function ($scope) {
    // variable passed to app controller
    $scope.$watch('variable', function (value) {
        if (value) {
            console.log(value);
        }
    });
}]);

这是html（记住括号！）：

<div ng-controller="MyCtrl">
    <div your-directive="{{ someObject.someVariable }}"></div>
    <!-- use ng-bind instead of {{ }}, when you can to avoids FOUC -->
    <div ng-bind="variable"></div>
</div>

另外，请看一下这个答案：https://stackoverflow.com/a/12372494/1008519

FOUC参考（无格式内容的闪现）问题：http://deansofer.com/posts/view/14/AngularJs-Tips-and-Tricks-UPDATED

感兴趣的是：here's an article on the angular life cycle

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