使用angular js在用户点击时动态添加表单字段

添加子按钮无法正常工作（应该在用户单击时添加各种字段（名字、mi、姓氏、学生和情况字段）。详细信息：我正在尝试创建一个由五个输入字段（名字、中间名、姓氏和两个单选按钮）组成的表单，如果用户单击添加子按钮，应该会创建一个新的五个输入域。

注意：我使用指令调用此表单）。

 <div ng-controller="Step1Ctrl" layout="column" layout-align="center">
 <div layout-gt-sm="row" layout-align="center">
     <div id="banner">
         <p> <span>STEP 1</span> List all household members who are infants,  children, and students up to and including grade 12</p>
    </div>
</div>
<md-content layout-padding>
    <form name="Form">
        <fieldset layout-gt-sm="row" layout-align="center" data-ng-repeat="child in childern">
            <md-input-container class="md-block">
                <label>First Name</label>
                <input required name="firstName" ng-model="child.firstName">
                <div ng-messages="Form.firstName.$error">
                    <div ng-message="required">First Name is required.</div>
                </div>
            </md-input-container>
            <md-input-container class="md-block" style="max-width:60px;">
                <label>MI</label>
                <input required name=" middleName " ng-model="child.middleName ">
                <div ng-messages="Form.middleName.$error ">
                    <div ng-message="required ">Middle Name is required.</div>
                </div>
            </md-input-container>
            <md-input-container class="md-block ">
                <label>Last Name</label>
                <input required name="lastName " ng-model="child.lastName ">
                <div ng-messages="Form.lastName.$error ">
                    <div ng-message="required ">Last Name is required.</div>
                </div>
            </md-input-container>
            <div class="cell ">
                <label> <b>Student?</b></label>
                <div class="box">
                    <md-radio-group ng-model="child.IsStudent">
                        <md-radio-button value="Yes">Yes</md-radio-button>
                        <md-radio-button value="No"> No </md-radio-button>
                    </md-radio-group>
                </div>
            </div>
            <div class="cell">
                <label><b> Child's situation? </b></label>
                <div class="box">
                    <md-radio-group ng-model="child.situation">
                        <md-radio-button value="Foster Child">Foster Child </md-radio-button>
                        <md-radio-button value="HMR"> Homeless, Migrant, Runaway </md-radio-button>
                    </md-radio-group>
                </div>
            </div>
        </fieldset>
    </form>
    <div layout-gt-sm="row" layout-align="center">
        <md-button class="md-raised md-primary" ng-click="Step1Ctrl.addChild()">Add Child</md-button>
    </div>
</md-content>
</div>

javascript

         var form =  angular . module ( 'myform'[ 'ngMaterial','     ngAnimate''ngMessages','ngRoute']);  
      form.directive('myStep1', function () {return { templateUrl: 
  'step1-form.html'};});
      form.controller('Step1Ctrl', function ($scope) {
$scope.childern = [];
$scope.addChild = function () {
    $scope.childern.push({});
};
$scope.removeChild = function () {
};
  });