AngularFire更新而不是重复数据

Question

我正在使用angularfire来保存和显示我的用户数据。他们填写的表单堆叠或复制数据而不是更新。我只想要一个显示最新数据，任何想法？我将它全部包含在一个面板中，用户名等内容列出了3次。

app.controller('infoCtrl', ['$scope', '$location', '$firebaseArray', 'Auth', 
  function($scope, $location, $firebaseArray, Auth) {
  this.userAuthData = Auth.$getAuth();

vm = this;
var ref = new Firebase('https://capstone-zhf.firebaseio.com/' + this.userAuthData.uid + '/surveyInfo');
ref.orderByChild('name').limitToLast(2).on("child_added", function(snapshot) {
});


vm.syncObject = $firebaseArray(ref);

var newInfo = {};

$scope.addInfo = function() {
    vm.syncObject.$add({
        q1: vm.newInfo.q1,
        q2: vm.newInfo.q2,
        q3: vm.newInfo.q3,
        q4: vm.newInfo.q4,
        q5: vm.newInfo.q5,
        q6: vm.newInfo.q6,
        q7: vm.newInfo.q7,
        weight: vm.newInfo.weight,
        height: vm.newInfo.height,
        name: vm.newInfo.name
    });
    vm.newInfo = {};
};

这是我的HTML代码

            <table>
                <tr ng-repeat="(id, info) in infoCtrl.syncObject">
                  <td class="panel-body">Goal: {{ info.q1 }}</td>  
                  <td class="panel-body">{{ info.q2 }}</td>
                  <td class="panel-body">{{ info.q5 }}</td>
                  <td>
                    <button ng-click="editNew(info)">Edit</button>
                  </td>
                  <td>
                    <button ng-click="infoCtrl.syncObject.$remove(id)">x</button>
                  </td>
                </tr>
            </table>