我有一个带有隔离范围的指令，该指令的值具有两种方式绑定到父范围。我正在调用一个方法来更改父作用域中的值，但是更改未应用到我的指令中。（不触发双向绑定）。

但是我不是从指令中更改值，而是仅在父范围中更改它。我阅读了解决方案，并指出了第五点：

The watch() created by the isolated scope checks whether it's value for the bi-directional binding is in sync with the parent's value. If it isn't  the parent's value is copied to the isolated scope.

这意味着当我的父值更改为2时，将触发监视。它检查父值和指令值是否相同-如果不相同，则将其复制到指令值。好的，但是我的指令值仍然是1 …我缺少什么？

html：

<div data-ng-app="testApp">
    <div data-ng-controller="testCtrl">
        <strong>{{myValue}}</strong>
        <span data-test-directive data-parent-item="myValue" 
            data-parent-update="update()"></span>
    </div>
</div>

js：

var testApp = angular.module('testApp', []);

testApp.directive('testDirective', function ($timeout) {
    return {
        scope: {
            key: '=parentItem',
            parentUpdate: '&'
        },
        replace: true,
        template:
            '<button data-ng-click="lock()">Lock</button>' +
            '</div>',
        controller: function ($scope, $element, $attrs) {
            $scope.lock = function () {
                console.log('directive :', $scope.key);

                 $scope.parentUpdate();
                 //$timeout($scope.parentUpdate); // would work.

                 // expecting the value to be 2, but it is 1
                 console.log('directive :', $scope.key);
            };
        }
    };
});

testApp.controller('testCtrl', function ($scope) {
    $scope.myValue = '1';
    $scope.update = function () {
        // Expecting local variable k, or $scope.pkey to have been
        // updated by calls in the directive's scope.
        console.log('CTRL:', $scope.myValue);
        $scope.myValue = "2";
        console.log('CTRL:', $scope.myValue);
    };
});

jsfiddle