angularjs ng-repeat 依赖的 selectBox

Question

我想让我的选择框可靠，所以，如果我选择区域 "America"，第二个选择框应该只显示纽约，但我不知道如何制作它，我尝试在我的选项中使用 ng-click，但它不起作用。而且我无法更改我的数据库类型，我需要使用它，所以有人知道如何在不更改任何数据库结构的情况下实现它吗？

var app = angular.module('app', []);
  
app.controller('ctrl', function($scope) {
$scope.countryList=[];
 $scope.data =[
 {id:1, country_code:"KR", country_name:"Korea", city_name:"Busan", city_code:"PUS"},
 {id:1, country_code:"KR", country_name:"Korea", city_name:"Seoul", city_code:"SEL"},
 {id:1, country_code:"KR", country_name:"Korea", city_name:"Ulsan", city_code:"USN"},
 {id:1, country_code:"KR", country_name:"Korea", city_name:"GwangJu", city_code:"KWJ"},
 {id:1, country_code:"KR", country_name:"Korea", city_name:"Gunsan", city_code:"KUV"},
 {id:1, country_code:"USA", country_name:"America", city_name:"New York", city_code:"NY"}
 ];
  
  
    for (var i = 0; i < $scope.data.length; i++) {
     var isExist = false;
     for (var j = 0; j < $scope.countryList.length; j++) {
      if (JSON.stringify($scope.data[i].country_code) == JSON.stringify($scope.countryList[j].country_code)) {
       isExist = true;
       break;
      }
     }
     if (isExist == false) {
      $scope.countryList.push($scope.data[i]);
     }
    }
});

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="app" ng-controller="ctrl">
<div class="port_small_select_div">
            <select class="small_select">
              <option disabled selected hidden>Region</option>
              <option ng-repeat="country in countryList" value="{{ country.country_code }}">{{ country.country_name}}</option>
            </select>
          </div>

          <div class="port_select_div">
            <select class="big_select">
              <option disabled selected hidden>Detailed information</option>
              <option ng-repeat="city in data" value="{{ city.city_code }}">{{ city.city_name}}</option>
            </select>
          </div>
          </div>

Answer 1

您可以根据第一个下拉列表的 select 的 country_code 对第二个下拉列表应用过滤器。我还将下拉列表替换为使用 ng-options。您还应该考虑将 ng-model 添加到每个 select 框。

<select class="small_select" ng-model="selectedRegion" 
  ng-options="country.country_name as country_code for in countryList">
  <option disabled selected hidden>Region</option>
</select>

<select class="big_select" ng-model="selectedCity"
 ng-options="city.city_code as city.city_name for city in data | filter: {country_code: selectedRegion }">
  <option disabled selected hidden>Detailed information</option>
</select>

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