AngularJS控制器和指令范围问题

Z时代
2024-01-10
分类：问答

过去几天我一直在继续研究angularjs，尤其是关于指令。AngularJS控制器和指令范围问题

我有一个场景，我必须加载一个记录列表，每个记录属于一个类别（5个类别在下拉选择框中）。我已经创建了一个指令来处理它们中的每一个的“更改”事件，并使它们的范围不重叠。正如您在控制台日志中所看到的，每次从下拉列表中选择一个项目时，它都是独立于其他项目的。

我有两个问题：

如何从外部资源只有一次加载的类别。到更具体一些，我只想调用 practiceFactory.getCategories（）一次。

是我的代码结构在正确的轨道方面？

这里是我的html：

<div data-ng-app="practiceApp"> 
    <h1>practiceAppController</h1> 
    <div data-ng-controller="practiceAppController"> 
     <p><select data-when-changed="saveCategory({{selectedCategoryId}})" data-ng-model="selectedCategoryId" data-ng-options="category.id as category.name for category in categories"></select></p> 
     <p><select data-when-changed="saveCategory({{selectedCategoryId}})" data-ng-model="selectedCategoryId" data-ng-options="category.id as category.name for category in categories"></select></p> 
     <p><select data-when-changed="saveCategory({{selectedCategoryId}})" data-ng-model="selectedCategoryId" data-ng-options="category.id as category.name for category in categories"></select></p> 
     <p><select data-when-changed="saveCategory({{selectedCategoryId}})" data-ng-model="selectedCategoryId" data-ng-options="category.id as category.name for category in categories"></select></p> 
     <p><select data-when-changed="saveCategory({{selectedCategoryId}})" data-ng-model="selectedCategoryId" data-ng-options="category.id as category.name for category in categories"></select></p> 
    </div> 
</div>

这里是我的JS：

var practiceApp = angular.module('practiceApp', []); 
practiceApp.controller('practiceAppController', function($scope, practiceFactory) { 
}); 
practiceApp.factory('practiceFactory', function() { 
    var factory = {}; 
    factory.getCategories = function() { // async call here 
     console.log('getCategories() was called'); 
     var categories = [ 
      {id: 1, name: 'Food & Dining'}, 
      {id: 2, name: 'Hotel & Travel'}, 
      {id: 3, name: 'Shopping'}, 
      {id: 4, name: 'Health & Beauty'}, 
      {id: 5, name: 'Activities'} 
     ]; 
     return categories; 
    } 
    factory.getSelectedCategory = function() { // async call here 
     console.log('getSelectedCategory() was called'); 
     var selectedCategoryId = Math.floor((Math.random()*5)+1); 
     return selectedCategoryId; 
    } 
    return factory; 
}); 
practiceApp.directive('whenChanged', function(practiceFactory) { 
    return { 
     restrict: 'A', 
     scope: {}, 
     controller: function ($scope) { 
      $scope.selectedCategoryId = practiceFactory.getSelectedCategory(); 
      $scope.categories = practiceFactory.getCategories(); 
      $scope.saveCategory = function(categoryId) { 
       console.log(categoryId); 
      } 
     }, 
     link: function(scope, element, attribute) { 
       element.bind('change', function() { 
        scope.$apply(attribute.whenChanged); 
       }) 
     } 
    } 
});