我有一个基于第一个下拉选择的带有第二个下拉菜单的级联选择。出现一个额外的空白选项,这不是下拉菜单预期行为的一部分。

<select ng-init="order.attempt_status_sub = order.attempt_status_sub || subStatuses[0].name"
    data-ng-model="order.attempt_status_sub" ng-options="subStatus.name as
    subStatus.name for subStatus in subStatuses">
</select>


如何避免下拉菜单中出现空的多余选择?



我的级联下拉列表的代码是

    <div class="form-group" ng-class="{ 'has-error' : submitted && orderForm.content.$invalid}">
      <div class="controls">
        <select ng-change="getSubStatuses(order.attempt_status)" data-ng-model="order.attempt_status" ng-options="status.name as status.name for status in statuses">
        </select>
      </div>
    </div>

    <div class="form-group" ng-show="subStatuses.length" ng-class="{ 'has-error' : submitted && orderForm.content.$invalid}">
      <div class="controls">
        <select ng-init="order.attempt_status_sub = order.attempt_status_sub || subStatuses[0].name" data-ng-model="order.attempt_status_sub" ng-options="subStatus.name as subStatus.name for subStatus in subStatuses">
        </select>
      </div>
    </div>


$scope.getSubStatuses = function(attempt_status) {

    var statuses = $scope.statuses;
    for(var index in statuses) {
        if(statuses[index].name === attempt_status) {

            if(statuses[index].children) {
                $scope.subStatuses = statuses[index].children;
            } else {
                $scope.subStatuses = [];
            }
            break;
        }
    }
};

最佳答案

我假设您正在为异步绑定的数据设置它。 ng-init对于此目的确实很不好。拇指法则是不要将ng-init用于控制器应该执行的操作。您应该在控制器中设置视图模型。当异步绑定数据时,它可能失败的原因是因为未监视ng-inited表达式。因此,它在第一次渲染期间仅运行一次,并且subStatuses尚未填充,并且回退到显示默认的空选项。并且即使在稍后的摘要周期中填充了数据并更新了视图,ng-init表达式也不会再次运行。

From Doc


  ngInit的唯一适当用法是为ngRepeat的特殊属性添加别名,如下面的演示所示。除了这种情况,您应该使用控制器而不是ngInit来初始化作用域上的值。


因此,只需在您的控制器中对其进行初始化,而不是使用ng-init。

$scope.getSubStatuses = function(attempt_status) {

    var statuses = $scope.statuses;
    for(var index in statuses) {
        if(statuses[index].name === attempt_status) {

            if(statuses[index].children) {
                $scope.subStatuses = statuses[index].children;
            } else {
                $scope.subStatuses = [];
            }
            break;
        }
    }
    //Initialize the model here, assuming $scope.order is already initialized
    $scope.order.attempt_status_sub = ($scope.subStatuses[0] ||{}).name;
};




angular.module('app', []).controller('ctrl', function($scope, $timeout) {

  $timeout(function() {
    $scope.subStatuses = [{
      name: 'test1'
    }, {
      name: 'test2'
    }, {
      name: 'test3'
    }];

    $scope.order = {
      attempt_status_sub1: $scope.subStatuses[0].name
    };

  });



});

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="app" ng-controller="ctrl">
  With Ng-Init
  <select ng-init="order.attempt_status_sub = order.attempt_status_sub || subStatuses[0].name" data-ng-model="order.attempt_status_sub" ng-options="subStatus.name as
    subStatus.name for subStatus in subStatuses">
  </select>

  With controller initialization.

  <select data-ng-model="order.attempt_status_sub1" ng-options="subStatus.name as
    subStatus.name for subStatus in subStatuses">
  </select>
</div>

09-30 16:45
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