javascript – AngularJS：父范围未更新的指令(带隔离范围)双向绑定

视图：

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

JS：

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

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

                // ExpecTing $scope.$parent.pkey to have also been
                // updated before invoking the next line.
                $scope.parentupdate();
                // $timeout($scope.parentupdatE); // would work.
            };
        }
    };
});

testApp.controller('TESTCtrl',function ($scope) {
    $scope.pkey = 'golden';
    $scope.update = function (k) {
        // ExpecTing local variable k,or $scope.pkey to have been
        // updated by calls in the directive's scope.
        console.log('CTRL:',$scope.pkey,k);
        $scope.pkey = 'C+' + k;
        console.log('CTRL:',$scope.pkey);
    };
});

基本上,我设置了一个隔离范围的指令,其中我从父范围(pkey)双向绑定一个属性(key),并且还委派一个方法(parentupdatE)在上下文中被调用的父范围.

现在,在指令中的ng-click事件处理程序中,我想调用parentupdate方法并在其中执行某些操作.当我调用该方法时,我期望我的父范围的模型被更新.但实际上,这不是,这是令我困惑的.

这可能是因为中间的一些缺少$摘要循环,因为用$timeout包装parentupdate调用将按预期工作.

有人会说出一些缺点吗？还是如何正确调用parentupdate？