Question

我正在关注Getting Started with Entity Framework 6 Code First using MVC 5教程。在本教程中，在视图中有两个表。当您从第一个（讲师）表中选择一行时，下表显示该讲师的课程。我无法理解这是怎么回事。在代码中哪些地方知道教师的课程？如果有人能向我解释这一点，我会非常高兴。提前致谢。这是控制器：

public ActionResult Index(int? id, int? courseID)
        {
            var viewModel = new InstructorIndexData();
            viewModel.Instructors = db.Instructors.Include(i => i.OfficeAssignment).Include(i => i.Courses.Select(c => c.Department))
                .OrderBy(i => i.LastName);

            if(id != null)
            {
                ViewBag.InstructorID = id.Value;
                viewModel.Courses = viewModel.Instructors.Where(i => i.ID == id.Value).Single().Courses;
            }

            if(courseID != null)
            {
                ViewBag.CourseID = courseID.Value;
                viewModel.Enrollments = viewModel.Courses.Where(x => x.CourseID == courseID).Single().Enrollments;
            }


            return View(viewModel);
        }

以下是观点：

@model ContosoUniversity.ViewModels.InstructorIndexData
@{
    ViewBag.Title = "Instructors";
}

<h2>Instructors</h2>

<p>
    @Html.ActionLink("Create New", "Create")
</p>
<table class="table">
    <tr>
        <th>
            Last Name
        </th>
        <th>
            First Name
        </th>
        <th>
            Hire Date
        </th>
        <th>
            Office
        </th>
        <th></th>
    </tr>

    @foreach (var item in Model.Instructors)
    {

        string selectedRow = "";
        if (item.ID == ViewBag.InstructorID)
        {
            selectedRow = "success";
        }

        <tr class="@selectedRow">
            <td>
                @Html.DisplayFor(modelItem => item.LastName)
            </td>
            <td>
                @Html.DisplayFor(modelItem => item.FirstMidName)
            </td>
            <td>
                @Html.DisplayFor(modelItem => item.HireDate)
            </td>
            <td>
                @if (item.OfficeAssignment != null)
                {
                    @item.OfficeAssignment.Location
                }
            </td>
            <td>
                @Html.ActionLink("Select", "Index", new { id = item.ID }) |
                @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>


@if (Model.Courses != null)
{
    <h3>Courses Taught by Selected Instructor</h3>
    <table class="table">
        <tr>
            <th></th>
            <th>Number</th>
            <th>Title</th>
            <th>Department</th>
        </tr>
        @foreach (var item in Model.Courses)
        {
            string selectedRow = "";
            if (item.CourseID == ViewBag.CourseID)
            {
                selectedRow = "success";
            }
            <tr class="@selectedRow">
                <td>
                    @Html.ActionLink("Select", "Index", new { courseID = item.CourseID })
                </td>
                <td>
                    @item.CourseID
                </td>
                <td>
                    @item.Title
                </td>
                <td>
                    @item.Department.Name
                </td>
            </tr>
        }
    </table>
}

Answer 1

if(id != null)
{
    ViewBag.InstructorID = id.Value;
    viewModel.Courses = viewModel.Instructors.Where(i => i.ID == id.Value).Single().Courses;
}

这是根据教师选择课程的代码。注意它首先根据id参数选择讲师并读取该讲师的课程

Answer 2

我认为代码很清楚，在索引操作中，它找到具有给定id的教师，这个街区：

def my_view(request)
    data = data['my_data']

    if request.method == 'POST':
        data_a = request.POST.get(data["data_a"])
        data_b = request.POST.get(data["data_b"])
        data_c = request.POST.get(data["data_c"])
        data_d = request.POST.get(data["data_d"])
        obj = WeatherData.objects.create(
            data_a=data_a, data_b=data_b,
            data_c=data_c, data_d=data_d,)
        # obj.save() --> you don't need save because you already called `create`

    return render(request, 'data.html', obj)

一切都由ViewBags完成，ViewBag.InstructorID定义了所选的

'讲师'，查看页面中的此块

if(id != null)
{
 ViewBag.InstructorID = id.Value;
viewModel.Courses = viewModel.Instructors.Where(i => i.ID == id.Value).Single().Courses;
}

选择具有“成功”类的“tr标签”

相同的课程逻辑

在ASP.NET MVC 5中选择表中的行

2 个答案: