Linq InsertOnSubmit 抛出异常：对象引用未设置到对象的实例

发布于 2024-12-08 11:54:25 字数 700 浏览 0 评论 0 原文

下面抛出异常。

传递给 InsertOnSubmit 的 course 对象属于 Linq 生成的 Course 类型。

 public ActionResult Course(CourseViewModel c)
 {
    Course course = (Course) c; //CourseViewModel is derrived from Course
    SchedulerDataContext db = new SchedulerDataContext();
    db.Courses.InsertOnSubmit(course);  // <- this is where exception is thrown
    db.SubmitChanges();
 }

此处和这里，但是，我不明白他们的答案。据说我没有及时创建对象。哪个对象以及到底需要发生什么？

原文

The following throws exception.

The course object that is being passed to InsertOnSubmit is of type Course that is generated by Linq.

 public ActionResult Course(CourseViewModel c)
 {
    Course course = (Course) c; //CourseViewModel is derrived from Course
    SchedulerDataContext db = new SchedulerDataContext();
    db.Courses.InsertOnSubmit(course);  // <- this is where exception is thrown
    db.SubmitChanges();
 }

There are already questions about this here and here, however, I don't understand their answer. Supposedly I'm not creating an object in time. Which object and what exactly needs to happen?

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

霓裳挽歌倾城醉 2024-12-15 11:54:25

您需要先创建 Course 对象，然后再尝试插入它。

Course course = new Course { ... set the properties .. };
SchedulerDataContext db = new SchedulerDataContext();
db.Courses.InsertOnSubmit(course);
db.SubmitChanges();

You need to create the Course object before you try to insert it.

Course course = new Course { ... set the properties .. };
SchedulerDataContext db = new SchedulerDataContext();
db.Courses.InsertOnSubmit(course);
db.SubmitChanges();

回复收藏 0 原文

~没有更多了~