Javascript 从对话框返回值

我正在使用ngDialog。由于某些原因，当我单击Close时，closePromise数据参数不会返回“空缺”对象，而是返回的值未定义

请告知如何将对话框中的值返回给呼叫控制器。下面是我的代码：

<script type="text/ng-template" id="firstDialogId">
<div class="ngdialog-message">

    <h3>Pick a School</h3>
    <div class="form-group">
        <md-input-container class="md-block" >
            <md-select ng-model="Vacancy" placeholder="Select a Vacancy" id="Md-select2" name="vacancy2" >
                <md-option ng-value="vac" ng-repeat="vac in vacancylist" >{{vac.JobTitle}}</md-option>
            </md-select>
        </md-input-container>
    </div>
</div>

<div class="ngdialog-buttons">
    <button type="button" class="ngdialog-button ngdialog-button-primary" ng-click="closeThisDialog(Vacancy)">Ok</button>
</div>

---

我缺少下面的值属性：

   <button type="button" class="ngdialog-button ngdialog-button-primary" value="OK" ng-click="closeThisDialog(Vacancy)">Ok</button>

Ok

   <button type="button" class="ngdialog-button ngdialog-button-primary" value="OK" ng-click="closeThisDialog(Vacancy)">Ok</button>