如何显示对象内某个对象字段的值？

Question

我真的不知道正确的词语来问我需要什么，这意味着我没有真正从谷歌获得任何东西，所以我只是想创建一个简单的例子。如果你能回答我的问题，或者只是指向我需要搜索的方向，那会很棒。

说我有这些类：

public class Teacher 
{ 
    public int teacherID { get; set; } 
    public string name { get; set; } 
} 

public class Course 
{ 
    [Key] 
    public int ID { get; set; } 
    public string courseName { get; set; } 
    public int? teacherID { get; set; } 
    public Teacher teacher { get; set; } 
} 

public class schoolDBContext : DbContext 
{ 
    public DbSet<Course> Courses { get; set; } 
    public DbSet<Teacher> Teachers { get; set; } 
} 

我如何在HTML老师的名字显示过程时显示。例如，当我对视图有以下内容时，教师姓名为空。我需要更改什么才能显示课程的教师姓名？

<table class="table"> 
    <tr> 
     <th> 
      @Html.DisplayNameFor(model => model.Name) 
     </th> 
     <th> 
      @Html.DisplayNameFor(model => model.teacher.Name) 
     </th> 
    </tr> 

@foreach (var item in Model) { 
    <tr> 
     <td> 
      @Html.DisplayFor(modelItem => item.Name) 
     </td> 
     <td> 
      @Html.DisplayFor(modelItem => item.teacher.Name) 
     </td> 
    </tr> 
} 

如此配置，我已经重写约30倍：

protected override void Seed(school.Models.schoolDBContext context) 
     { 
      context.Courses.AddOrUpdate(i => i.ID, 
       new Course 
       { 
        courseName = "Math", 
        teacher = new Teacher { teacherID = 1, name = "Ms. Brooks" }, 
        teacherID = 1 
       }, 
       new Course 
       { 
        courseName = "Science", 
        teacher = new Teacher { teacherID = 2, name = "Ms. James" }, 
        teacherID = 2 
       }, 
       new Course 
       { 
        courseName = "History", 
        teacher = new Teacher { teacherID = 3, name = "Ms. Davidson" }, 
        teacherID = 3 
       } 
      ); 
     } 

的页面看起来是这样的。

但如果我这样做的控制器：

public ActionResult Index() 
     { 
      var _coursesList = new List<Course>(); 
      _coursesList.Add(new Course { ID = 1, courseName = "English", teacherID = 1, teacher = new Teacher { teacherID = 1, name = "Mrs. Thomas" } }); 
      _coursesList.Add(new Course { ID = 2, courseName = "History", teacherID = 2, teacher = new Teacher { teacherID = 2, name = "Ms. Jones" } }); 
      _coursesList.Add(new Course { ID = 3, courseName = "Math", teacherID = 2, teacher = new Teacher { teacherID = 2, name = "Ms. Fisher" } }); 

      return View(_coursesList); 

      // return View(db.Courses.ToList()); 
     } 

我得到这个：

Answer 1

我不知道ID我明白你的问题，但我认为你可以创建一个只读属性，如下所示：

public class Course 
{ 
    public int CourseID { get; set; } 
    public String Name { get; set; } 
    public Teacher Teacher { get; set; } 
    public String TeacherName 
    { 
     get { 
      return Teacher?.Name ?? Name 
     } 
    } 
} 

<table class="table"> 
    <tr> 
     <th> 
      @Html.DisplayNameFor(model => model.Name) 
     </th> 
     <th> 
      @Html.DisplayNameFor(model => model.TeacherName) 
     </th> 
    </tr> 

@foreach (var item in Model) { 
    <tr> 
     <td> 
      @Html.DisplayFor(modelItem => item.Name) 
     </td> 
     <td> 
      @Html.DisplayFor(modelItem => item.Teacher.Name) 
     </td> 
    </tr> 
} 

Answer 2

请确保您有填写Model对象

例：

public ActionResult Index() 
    { 
     var _courselst = new List<Course>(); 
     _courselst.Add(new Course { CourseID = 1, Name = "IT", Teacher = new Teacher { Name = "Scot", TeacherID = 1 } }); 
     _courselst.Add(new Course { CourseID = 2, Name = "ACC", Teacher = new Teacher { Name = "Manj", TeacherID = 2 } }); 
     _courselst.Add(new Course { CourseID = 3, Name = "MATHS", Teacher = new Teacher { Name = "Demion", TeacherID = 3 } }); 

     return View(_courselst); 
    }