AngularJS中的更新模型绑定单选按钮问题

我需要帮助才能正确填写表格中的最后一项。这是一个简单的页面,我有一个问题和一些答案。其中一个答案可以设置为正确,但这并不总是正确的。但一个问题只能有一个正确答案,所以我使用单选按钮。我的初始模型绑定工作正常,只选择了正确的答案。但是当我选择另一个答案时,我的模型没有在控制器中更新?

下面是我在jsfiddle中的示例: http://jsfiddle.net/dnrn/tujaxx03/12/

这是我的表格:

<form name="questionForm" ng-controller="QuestionEditController as controller">
{{ hello }}
    <b>Spørgsmål:</b> <input ng-model="question.Question" name="questionText" type="text" size="100"/> <br/>
    <b>Spørgsmål Engelsk:</b> <input ng-model="question.EnglishQuestion" name="questionText" type="text" size="100" />

    <br />

    <b>Svarmuligheder:</b>
    <div ng-repeat="answer in question.Answers">
        <b>Dansk</b> <input ng-model="answer.Answer" size="35" /> 
        <b>Englesk</b> <input ng-model="answer.EnglishAnswer" size="35" />
        <input ng-model="answer.IsCorrect" name="Correct" type="radio" ng-value="answer.IsCorrect" ng-click="setCorrectAnswer(answer.Id)" />
        <a href="">Slet</a>
    </div>       

    <input type="submit" value="Gem"/>

我的控制器:

var app = angular.module('myApp',[]);
app.controller('QuestionEditController', ['$scope', function ($scope){
    $scope.question = {
            "Id": 58, "Question": "Hvem opdagede Jupiters 4 måner Europa, Io, Ganyedes og Callisto?", "EnglishQuestion": "Who discovered Jupiter’s 4 moons: Europa, Io, Ganymede and Callisto?", "GermanQuestion": "", "Answers":
                [{ "Id": 130, "Answer": "Leonardo da Vinci i 1507", "EnglishAnswer": "Leonardo da Vinci in 1507", "GermanAnswer": "", "IsCorrect": false },
                    { "Id": 131, "Answer": "Tycho Brahe i 1599", "EnglishAnswer": "Tycho Brahe in 1599", "GermanAnswer": "", "IsCorrect": false },
                    { "Id": 132, "Answer": "Galileo Galilei i 1610", "EnglishAnswer": "Galileo Galilei in 1610", "GermanAnswer": "", "IsCorrect": true }],
            "AnswerCount": 0
        };

    $scope.save = function() {
        $scope.saved = $scope.question.Answers.filter(function (answer) {
            if (answer.IsCorrect) {
                return answer;
            }
        });
        };
}]);