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我有一个级联选择，第二个下拉列表基于第一个下拉选择出现​​。出现一个额外的空白选项，它不是下拉列表的预期行为的一部分。

<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>

如何避免出现在下拉列表中的空额外选择？

在此处输入图像描述

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;
        }
    }
};
4

1 回答 1

4

我假设您正在为异步绑定数据设置它。ng-init对于这个目的来说真的很糟糕。拇指规则不ng-init用于控制器应该做的事情。您应该在控制器中设置视图模型。异步绑定数据时它可能失败的原因是因为未监视 ng-init'ed 表达式。所以它只在第一次渲染期间运行一次，并且subStatuses尚未填充，它会回退到显示默认的空选项。并且即使在稍后的摘要循环期间填充了数据并更新了视图，ng-init 表达式也不会再次运行。

来自文档

ngInit 唯一合适的用途是为 ngRepeat 的特殊属性设置别名，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。

所以只需在你的控制器中初始化它，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>

于 2015-01-12T19:29:05.927 回答