如何将数组数据绑定到angularjs中的下拉列表中？

Question

你好，我正在用angularjs开发web应用程序。我正在尝试将数据绑定到drodpown。我正在进行ajax调用以从服务器获取数据。我得到错误不能读取属性‘长度’的未定义。我在提出请求。这是我的api。http://192.168.0.213:1234/api/Customer/Nationalities

上述api将返回

{"status":"Success","msg":"Success","code":"200","data":[{"ID":1,"Nationality":"indian"},{"ID":2,"Nationality":"england"}]}

我使用js绑定，如下所示。

  var url = cfg.Baseurl;
            var nationality = new Array();
            $http.get(url + 'api' + '/Customer/' + 'Nationalities').success(function (data) {
                $.map(data.data.Nationality, function (item) {
                    nationality.push(item);
                    console.log(item);
                });
                $scope.nationalityList = nationality;
            }).error(function (status) {
            });

这是我的html代码。

   <select ng-model="user.nationality" id="brand" ng-options="user.nationality for user in nationalityList" required>
                            <option value="" label="Select">Select</option>
                        </select>

最后，我无法读取未定义错误的属性“长度”。任何帮助都将不胜感激。谢谢。

Answer 1

下面是演示链接Jsfiddle演示

JS代码

  var app = angular.module('myApp', []);

  app.controller('ctrl', function($scope) {
    $scope.nationalityList = {
      "status": "Success",
      "msg": "Success",
      "code": "200",
      "data": [{
        "ID": 1,
        "Nationality": "indian"
      }, {
        "ID": 2,
        "Nationality": "england"
      }]
    };
  });

** HTML **

  <div ng-app='myApp'>

    <div ng-controller='ctrl'>
      <select ng-model="user.nationality" id="brand" ng-options="user.Nationality for user in nationalityList.data" required>
        <option value="" label="Select">Select</option>
      </select>
      <span>nationality = {{user.nationality}}</span>
    </div>
  </div>

希望这能帮到你

Answer 2

在这种情况下，不需要映射，它只分配数组的值。

var url = cfg.Baseurl;
var nationality = [];
$http.get(url + 'api' + '/Customer/' + 'Nationalities')
.success(function (data) {
    if(data.data) {
        // Here the value is assigned
        $scope.nationalityList = data.data;
    }
}).error(function (status) { });

你的html必须是这样的

<select
    ng-model="selectedNationality"
    id="brand"
    ng-options="item.Nationality for item in nationalityList" 
    required>
    <option value="" label="Select">Select</option>
</select>
<!-- Showing selected option -->
<p ng-if="selectedNationality">Selected option: {{selectedNationality}}<p/>

有关更多信息，https://docs.angularjs.org/api/ng/directive/ngOptions

Answer 3

由于未初始化$scope.nationalityList，因此在呈现视图时未定义它。因此出现了错误Cannot read property 'length' of undefined error.。

只需将变量初始化为空数组即可解决此错误。