c# - 我是在正确地播种数据还是做错了什么？

Question

我正在尝试显示另一个对象中的一个对象的值。几天来我一直在重写它，并用谷歌搜索它以试图找出我哪里出错了。我从一个复杂得多的项目开始，但现在我写了一个非常简单的学校项目，用作示例并尝试不同的东西。我已经根据 Internet 上的示例以至少 30 种不同的方式重写了配置，但到目前为止没有任何效果。非常感谢任何帮助我摆脱困境的帮助!

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; }
}

配置:

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
            }
       );
    }
}

查看:

@model IEnumerable<school.Models.Course>

@{
    ViewBag.Title = "Index";
}

<h2>Index</h2>

<p>
    @Html.ActionLink("Create New", "Create")
</p>
<table class="table">
    <tr>
        <th>
            @Html.DisplayNameFor(model => model.courseName)
        </th>
        <th>
        @Html.DisplayNameFor(model => model.teacher.name)
        </th>
        <th></th>
    </tr>

@foreach (var item in Model) {
    <tr>
        <td>
            @Html.DisplayFor(modelItem => item.courseName)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.teacher.name)
        </td>
        <td>
            @Html.ActionLink("Edit", "Edit", new { id=item.ID }) |
            @Html.ActionLink("Details", "Details", new { id=item.ID }) |
            @Html.ActionLink("Delete", "Delete", new { id=item.ID })
        </td>
    </tr>
}

</table>

如何让教师的姓名显示在类(class) View 中？

如果我在 Controller 中执行此操作，一切正常。

 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());
    }

所以问题一定出在我播种数据的方式上，对吧？

Answer 1

这些行:

<td>
        @Html.DisplayFor(modelItem => item.courseName)
    </td>
    <td>
        @Html.DisplayFor(modelItem => item.teacher.name)
    </td>

在 lambda 中:

DisplayFor(modelItem => item.teacher.name)

看起来你拿错了东西。

虽然，根据您创建迭代的方式，您为什么不使用:

@item.teacher.name

代替:

@Html.DisplayFor(modelItem => item.teacher.name)