Javascript 两个指令引用一个变量，但第二个指令不'；Don’不要找零就开枪

我有两个指令引用同一个父变量。第一个指令是下拉菜单。第二个指令是表。我试图做到的是：当在下拉列表中进行选择时，父变量将发生变化。使用$scope.$watch的第二个指令将检测此更改并将数据加载到表中。问题是第二条指令没有检测到变化。我不明白为什么

// home.html
<div>
    <directive-one testid="home.changevalue"></directive-one>
    <br />
    <directive-two testid="home.changevalue"></directive-two>
</div>

// search.directive.html
<div style="margin-top:5px;margin-left:25px;">
    <div class="row" style="margin-bottom:10px;">
        <label for="searchoptions" style="margin-left:15px;">Food Items</label>
        <br />
        <select style="margin-left:15px;" name="searchoptions" id="searchoptions1" ng-model="searchFoodItems.fooditemid" ng-change="searchFoodItems.onSelectionChange()">
            <option value="">Select ...</option>
            <option ng-repeat="fooditem in searchFoodItems.fooditems" value="{{fooditem.entryid}}">{{fooditem.itemdesc}}</option>
        </select>
        &nbsp;&nbsp;&nbsp;
        <span>Food Item ID - {{searchFoodItems.fooditemid}}</span>
    </div>
</div>

// list.directive.html
<div style="margin-top:5px;margin-left:30px;">
    <table class="table table-responsive">
        <thead>
            <tr>
                <th>ID</th>
                <th>Description</th>
                <th>Discount</th>
            </tr>
        </thead>
        <tfoot></tfoot>
        <tbody>
            <tr ng-repeat="row in listFoodItems.fullitemdescs">
                <td>{{row.EntryId}}</td>
                <td>{{row.ItemDesc}}</td>
                <td>{{row.ItemDisc}}</td>
            </tr>
        </tbody>
    </table>
</div>

---

从监视程序中删除函数和$scope

//function watchFoodItem() {

            $scope.$watch("fooditemid", function (value) {
                $q.all([load(value)]).then(function () { logger.log('list.directive.js - fooditemid changed'); });
            });
//        }

//function watchFoodItem() {

            $scope.$watch("fooditemid", function (value) {
                $q.all([load(value)]).then(function () { logger.log('list.directive.js - fooditemid changed'); });
            });
//        }