在ng-repeat上将选择默认值设置为空

Question

我有这个选择，我需要默认值为空，尝试添加一个值为“？”的选项并选择=“选中”，但它不会工作，任何想法？

<select class="form-control" 
        id="Select7" 
        name="grossweightmeasurementunitcode" 
        ng-model="itemForm.grossweightmeasurementunitcode" 
        ng-required="true">
        <option ng-repeat="unidadepeso in unidadespeso" value="{{unidadepeso.commoncode}}">{{unidadepeso.sigla}}</option>
 </select>

Answer 1

试试这个：

<select 
                        class="form-control" 
                        id="Select7" 
                        name="grossweightmeasurementunitcode" 
                        ng-model="itemForm.grossweightmeasurementunitcode" 
                        ng-required="true">
<option value="">--Select--</opton>
                            <option ng-repeat="unidadepeso in unidadespeso" value="{{unidadepeso.commoncode}}">{{unidadepeso.sigla}}</option>
                    </select>