angularjs – 单选按钮指令不绑定ngModel

<cs-radio-field options="gender" ng-model="genderValue"></cs-radio-field>

而选项就像

$scope.gender = { label: "Gender",required:true,valueList: [{ text: "Male",value: "yes" },{text:"Female",value:"no"}] };

该指令定义为：

app.directive("csRadioField",function () {
    var templateHtml = function () {
        return '<div ng-form="myform">' +
                '<div class="control-group" class="{{options.class}}">' +
                    '<div class="control-label">{{options.label || "Radio"}} {{ options.required ? "*" : ""}} </div>' +
                    '<div class="controls">' +
                        '<div class="radio" ng-repeat="(key,option) in options.valueList">' +
                            '<label> <input type="radio" name="myfield" ng-value="option.value" ng-model="ngModel" ng-required="options.required" />{{option.text}} </label>' +
                        '</div>' +
                        '<div class="field-validation-error" data-ng-show="myform.myfield.$invalid && myform.myfield.$dirty"> ' +
                            '<div data-ng-show="myform.myfield.$error.required">{{options.label}} is required!!!</div>' +
                        '</div>' +
                    '</div>' +
                '</div>' +
            '</div>';
    };

    return {
        scope: { options: '=',ngModel: '=' },required: ['ngModel','^form'],restrict: 'E',template: templateHtml,};
});

但是ngModel在父作用域中没有绑定…主要是因为ng-repeat创建了新的作用域.

怎么解决这个问题？

plunker链接：http://plnkr.co/edit/myS5hXwxjoDEqQI2q5Q7?p=preview