无法使用 AngularJs 在数字“1”上创建 属性 'subjects'

Cannot create property 'subjects' on number '1' using AngularJs

我想 select 跨一门课程学习多个科目,但我做不到

我有两个下拉列表,一个用于课程 selection,另一个用于科目 selection。对于我使用 angular-chosen 插件的多个 select 主题,只有在课程未从下拉列表中 select 编辑的情况下,我才能 select 多个主题。但是,当我 select 下拉列表中的课程时,我什至不能 select 下拉列表中的一个主题

以下是我的 AddCourseController.js 和相关的 HTML

(function() {

  var myApp = angular.module("myApp");

  var AddCourseController = function($scope, CourseService, TeacherService) {

    var onCourses = function(courses) {
      $scope.courses = courses;
    }
    var onError = function(response) {
      $scope.error = true;
      $scope.errors = response.data;
    };
    CourseService.courses().then(onCourses, onError);
    TeacherService.getSubjects().then(function(data) {
      $scope.subjects = data
    });
  };

  myApp.controller("AddCourseController", AddCourseController);
}());
<div class="form-group">
  <label>Select Course</label>
  <select ng-model="course" class="form-control"
          ng-options="course.IdCourse as course.Name for course in courses track by course.IdCourse">
  </select>
</div>
<div class="form-group" ng-class="{ 'has-error' : 
   addCourseForm.subjects.$invalid && !addCourseForm.subjects.$pristine }">
  <label class="pull-left">Select Subjects</label>
  <a class="pull-right btn btn-primary btn-xs" data-toggle="modal" data- target="#add-subject">Add Subject</a>
  <select chosen multiple class="form-control" 
          ng-model="course.subjects"
          ng-options="subject.IdSubject as subject.Name for subject in subjects">
  </select>
  <p ng-show="addCourseForm.subjects.$invalid && 
  !addCourseForm.subjects.$pristine" class="help-block">Subject is required.
  </p>
</div>

将课程选择器更改为 return 将整个 course 对象更改为 ng-model:

<div class="form-group">
  <label>Select Course</label>
  <select ng-model="course" class="form-control"
          ng-options="course ̶.̶I̶d̶C̶o̶u̶r̶s̶e̶ as course.Name for course in courses track by course.IdCourse">
  </select>
</div>