AngularJS 当第一个下拉菜单更改时，第二个下拉菜单不更新

Question

我正在创建一个搜索页面，用户可以在其中使用第一个下拉列表中列出的预先 selected 搜索条件搜索数据。在下面的示例中，这些条件是 'First Name'、'Country' 和 'Nationality'.

当用户 select 的国家或国籍时，第二个下拉列表出现在 select countries/nationalities 之一。为了填充这个下拉列表，我使用 ng-options 和一个内部变量，该变量指向控制器中定义的字符串。

但是当这两个选项之一被 selected 并且您想切换到另一个时，第二个下拉列表不会更新。 ngOptions 中的值确实在 HTML 中得到更新，只是下拉列表中的数据没有。

当你 select 'First Name' 之间没有问题。有谁知道我可以使用什么来更新第二个下拉列表中的值？

下面是我的代码和一个有效的 plunker：http://plnkr.co/edit/LYpOdoLpgiMeHxlGzmub?p=preview

var myApp = angular.module('myApp', []);
myApp.controller("SomeController", function($scope) {
  
    var vm = this;
    
    vm.search = {id:0, criteria: {}, value: ''};
    
    vm.referenceData = {
      countries: [
        {COUNTRY_ID:1, COUNTRY_NAME: 'UNITED KINGDOM'},
        {COUNTRY_ID:2, COUNTRY_NAME: 'AUSTRALIA'},
        {COUNTRY_ID:3, COUNTRY_NAME: 'SOUTH AFRICA'},
        {COUNTRY_ID:4, COUNTRY_NAME: 'NETHERLANDS'},  
      ],
      nationalities: [
        {NATIONALITY_ID: 1, NATIONALITY_NAME: "BRITISH"},
        {NATIONALITY_ID: 2, NATIONALITY_NAME: "AUSTRALIAN"},
        {NATIONALITY_ID: 3, NATIONALITY_NAME: "SOUTH AFRICAN"},
        {NATIONALITY_ID: 4, NATIONALITY_NAME: "DUTCH"},  
        ]
    };
    
    vm.criteriaList = [
        { name: 'First Name', key: 'FIRST_NAME'},
        { name: 'Country', key: 'COUNTRY_ID', options:'o.COUNTRY_ID as o.COUNTRY_NAME for o in ctrl.referenceData.countries' },
        { name: 'Nationality', key: 'NATIONALITY', options:'o.NATIONALITY_ID as o.NATIONALITY_NAME for o in ctrl.referenceData.nationalities' }
    ];
});

<!DOCTYPE html>
<html>

<head>
  <script data-require="angular.js@1.6.2" data-semver="1.6.2" src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.2/angular.js"></script>
  <link rel="stylesheet" href="style.css" />
  <script src="script.js"></script>
</head>

<body ng-app="myApp" ng-controller="SomeController as ctrl">


  <p>Criteria:</p>
  <select ng-model="search.criteria" ng-change="search.value = ''" ng-options="criteria as criteria.name for criteria in ctrl.criteriaList">
    <option value="">- Select Criteria -</option>
  </select>
  
  
  <p>Value:</p>
  <!-- TEXT INPUT -->
  <input type="text" ng-model="search.value" placeholder="Search Value" ng-if="!search.criteria.options" />
  <!-- DROPDOWN INPUT -->
  <select ng-model="search.value" ng-if="search.criteria.options" ng-options="{{search.criteria.options}}"></select>

</html>

Answer 1

这是一个简单的修复方法，您只需要一个变量，它可以在您每次切换时从第二个下拉列表中退出。 dom 需要一些东西来强制它刷新，因为没有 scope.$apply 发生。

Plunker Working

试试这个：

var myApp = angular.module('myApp', []);
myApp.controller("SomeController", function($scope, $timeout) {

    var vm = this;
    vm.somVal = false; ///ADD THIS
    vm.search = {id:0, criteria: {}, value: ''};

    vm.triggerSomeVal = function(){ ///ADD THIS
      vm.someVal = true;
      $timeout(function(){vm.someVal = false}, 100)
    };

    vm.referenceData = {
      countries: [
        {COUNTRY_ID:1, COUNTRY_NAME: 'UNITED KINGDOM'},
        {COUNTRY_ID:2, COUNTRY_NAME: 'AUSTRALIA'},
        {COUNTRY_ID:3, COUNTRY_NAME: 'SOUTH AFRICA'},
        {COUNTRY_ID:4, COUNTRY_NAME: 'NETHERLANDS'},  
      ],
      nationalities: [
        {NATIONALITY_ID: 1, NATIONALITY_NAME: "BRITISH"},
        {NATIONALITY_ID: 2, NATIONALITY_NAME: "AUSTRALIAN"},
        {NATIONALITY_ID: 3, NATIONALITY_NAME: "SOUTH AFRICAN"},
        {NATIONALITY_ID: 4, NATIONALITY_NAME: "DUTCH"},  
        ]
    };

    vm.criteriaList = [
        { name: 'First Name', key: 'FIRST_NAME'},
        { name: 'Country', key: 'COUNTRY_ID', options:'o.COUNTRY_ID as o.COUNTRY_NAME for o in ctrl.referenceData.countries' },
        { name: 'Nationality', key: 'NATIONALITY', options:'o.NATIONALITY_ID as o.NATIONALITY_NAME for o in ctrl.referenceData.nationalities' }
    ];
});

<p>Criteria:</p>
  <select ng-model="search.criteria" ng-change="search.value = ''; ctrl.triggerSomeVal()" ng-options="criteria as criteria.name for criteria in ctrl.criteriaList">
    <option value="">- Select Criteria -</option>
  </select>


  <p>Value:</p>
  <!-- TEXT INPUT -->
  <input type="text" ng-model="search.value" placeholder="Search Value" ng-if="!search.criteria.options" />
  <!-- DROPDOWN INPUT ADD !someVal-->
  <select ng-model="search.value" ng-if="search.criteria.options && !ctrl.someVal" ng-options="{{search.criteria.options}}"></select>

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