angularjs：级联下拉菜单

Question

我正在尝试在 Angular 中实现级联下拉菜单。我认为由于绑定，它会自然而然地工作。见下文：

<select name="client" ng-model="selectedRequest.client" ng-options="c.name for c in clients track by c.id" required></select>
<select id="department" ng-model="selectedRequest.department" ng-options="d.defaultLabel for d in selectedRequest.client.departments track by d.id"></select>

加载视图后，它可以工作，我可以看到与绑定到客户端的部门匹配的部门。但是，每当 selectedRequest.client 更改时，部门下拉列表的源也应该更改，但它会变为空。

编辑

我已将子下拉菜单更改为：

<select id="department" ng-model="selectedRequest.department" ng-options="d.defaultLabel for d in departments track by d.id | filter:{clientId: selectedRequest.client.id}"></select>

但这次它会加载下拉列表中的所有部门，忽略过滤器。

** 编辑 2 **

改为：

 <select name="client" ng-model="requestService.selectedRequest.client" ng-options="c as c.name for c in clients track by c.id" required></select>

 <select id="department" ng-model="requestService.selectedRequest.department" ng-options="d.defaultLabel for d in departments  | filter:{clientId: requestService.selectedRequest.client.id}"></select>

现在选择客户端时源会正确更改。然而，初始选择，即在启动时设置正确的部门，不起作用。那是因为我删除了 'track by id' 位。

Answer 1

正确的方法是

 <select id="department" ng-model="selectedRequest.department" ng-options="d.defaultLabel for d in departments | filter:{clientId: selectedRequest.client.id} track by d.id "></select>

只是我没有将过滤器放在正确的位置......愚蠢的错误。

Answer 2

可能是您的selectedRequest.client 在clients 数组中引用的对象不同。试试这个：

JS：

function testController($scope) {
            $scope.clients = [
             { id: 1, name: "client1", departments: [{ id: 1, defaultLabel: 'department1' }, { id: 2, defaultLabel: 'department2'}] },
             { id: 2, name: "client2", departments: [{ id: 3, defaultLabel: 'department3' }, { id: 4, defaultLabel: 'department4'}] }
            ];

             $scope.selectedRequest = {};
             $scope.selectedRequest.client = $scope.clients[0];//Assign by object reference.
        }

HTML：

<div ng-controller="testController">
        <select name="client" ng-model="selectedRequest.client" ng-options="c.name for c in clients" required></select>
        <select id="department" ng-model="selectedRequest.department" ng-options="d.defaultLabel for d in selectedRequest.client.departments"></select>
    </div>

DEMO

我删除了track by 以使用默认值（按对象引用跟踪）并确保selectedRequest.client 引用clients 中的对象