(Edit/5) 不工作但 (edit?id=5) 在 MVC 5 中工作

Question

我刚开始学习 MVC，我试图将 studentId 作为参数传递给编辑页面。默认情况下，当您单击编辑链接时，它会转到：

 localhost:63348/student/Edit/5 

但它不起作用。它给了我这个错误

参数字典包含“WebApplication1.Controllers.StudentController”中方法“System.Web.Mvc.ActionResult Edit(Int32)”的不可空类型“System.Int32”的参数“StudentId”的空条目。

但如果我手动将其更改为：

 localhost:63348/student/Edit?studentid=5

它然后工作。他们应该意思相同并且工作方式几乎相同吗？

这是我的控制器：

public IList<Student>studentList = new List<Student>{
            new Student() { StudentId = 1, StudentName = "John", Age = 18 } ,
            new Student() { StudentId = 2, StudentName = "Steve",  Age = 21 } ,
            new Student() { StudentId = 3, StudentName = "Bill",  Age = 25 } ,
            new Student() { StudentId = 4, StudentName = "Ram" , Age = 20 } ,
            new Student() { StudentId = 5, StudentName = "Ron" , Age = 31 } ,
            new Student() { StudentId = 6, StudentName = "Chris" , Age = 17 } ,
            new Student() { StudentId = 7, StudentName = "Rob" , Age = 19 }
        };

    [Route("Edit/{studentId:int")]
    public ActionResult Edit(int StudentId)
    {
        //Get the student from studentList sample collection 
        var std = studentList.Where(s => s.StudentId == StudentId).FirstOrDefault();

        return View(std);
    }

尝试添加特定的路由配置，但也没有用：

routes.MapRoute(
            name: "StudentEdit",
            url: "{controller}/{action}/{id}",
            defaults: new { controller = "Student", action = "Edit", id = UrlParameter.Optional }
        );

Answer 1

您需要添加属性[FromUri]并更正编译问题（提供右括号}并且参数名称不一样。

[Route("Edit/{studentId:int}")]
    public ActionResult Edit([FromUri] int studentId)
    {
        //Get the student from studentList sample collection 
        var std = studentList.Where(s => s.StudentId == StudentId).FirstOrDefault();

        return View(std);
    }