MVC与EF结合：Contoso大学

中文教程

1、通过 MVC 5 使用 Entity Framework 6 Code First 入门

https://docs.microsoft.com/zh-cn/aspnet/mvc/overview/getting-started/getting-started-with-ef-using-mvc/creating-an-entity-framework-data-model-for-an-asp-net-mvc-application

2、通过 MVC 4 使用 Entity Framework 5 Code First 入门

https://docs.microsoft.com/zh-cn/aspnet/mvc/overview/older-versions/getting-started-with-ef-5-using-mvc-4/

3、通过 ASP.NET Core MVC 使用 Entity Framework Core  入门

https://docs.microsoft.com/zh-cn/aspnet/core/data/ef-mvc/?view=aspnetcore-2.1

示例源码下载

1、Contoso University - Entity Framework 6 and ASP.NET MVC 5

https://code.msdn.microsoft.com/ASPNET-MVC-Application-b01a9fe8

2、Contoso University - Entity Framework Core in an ASP.NET Core MVC

https://github.com/aspnet/Docs/tree/master/aspnetcore/data/ef-mvc/intro/samples/cu-final

一、Models：模型

public abstract class Person
{
    [Key]
    public int PersonID { get; set; }

    [Required(ErrorMessage = "Last name is required.")]
    [Display(Name = "Last Name")]
    [MaxLength()]
    public string LastName { get; set; }

    [Required(ErrorMessage = "First name is required.")]
    [Column("FirstName")]
    [Display(Name = "First Name")]
    [MaxLength()]
    public string FirstMidName { get; set; }

    public string FullName
    {
        get
        {
            return LastName + ", " + FirstMidName;
        }
    }
}
public class Student : Person
{
    [Required(ErrorMessage = "Enrollment date is required.")]
    [DisplayFormat(DataFormatString = "{0:d}", ApplyFormatInEditMode = true)]
    [Display(Name = "Enrollment Date")]
    public DateTime? EnrollmentDate { get; set; }

    public virtual ICollection<Enrollment> Enrollments { get; set; }
}
public class Enrollment
{
    public int EnrollmentID { get; set; }

    public int CourseID { get; set; }

    public int PersonID { get; set; }

    [DisplayFormat(DataFormatString = "{0:#.#}", ApplyFormatInEditMode = true, NullDisplayText = "No grade")]
    public decimal? Grade { get; set; }

    public virtual Course Course { get; set; }
    public virtual Student Student { get; set; }
}
public class Course
{
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    [Display(Name = "Number")]
    public int CourseID { get; set; }

    [Required(ErrorMessage = "Title is required.")]
    [MaxLength()]
    public string Title { get; set; }

    [Required(ErrorMessage = "Number of credits is required.")]
    [Range(, , ErrorMessage = "Number of credits must be between 0 and 5.")]
    public int Credits { get; set; }

    [Display(Name = "Department")]
    public int DepartmentID { get; set; }

    public virtual Department Department { get; set; }
    public virtual ICollection<Enrollment> Enrollments { get; set; }
    public virtual ICollection<Instructor> Instructors { get; set; }
}
public class Department
{
    public int DepartmentID { get; set; }

    [Required(ErrorMessage = "Department name is required.")]
    [MaxLength()]
    public string Name { get; set; }

    [DisplayFormat(DataFormatString = "{0:c}")]
    [Required(ErrorMessage = "Budget is required.")]
    [Column(TypeName = "money")]
    public decimal? Budget { get; set; }

    [DisplayFormat(DataFormatString = "{0:d}", ApplyFormatInEditMode = true)]
    [Required(ErrorMessage = "Start date is required.")]
    public DateTime StartDate { get; set; }

    [Display(Name = "Administrator")]
    public int? PersonID { get; set; }

    [Timestamp]
    public Byte[] Timestamp { get; set; }

    public virtual Instructor Administrator { get; set; }
    public virtual ICollection<Course> Courses { get; set; }
}
public class Instructor : Person
{
    [DisplayFormat(DataFormatString = "{0:d}", ApplyFormatInEditMode = true)]
    [Required(ErrorMessage = "Hire date is required.")]
    [Display(Name = "Hire Date")]
    public DateTime? HireDate { get; set; }

    public virtual ICollection<Course> Courses { get; set; }

    public virtual OfficeAssignment OfficeAssignment { get; set; }
}
public class OfficeAssignment
{
    [Key]
    public int PersonID { get; set; }

    [MaxLength()]
    [Display(Name = "Office Location")]
    public string Location { get; set; }

    public virtual Instructor Instructor { get; set; }
}

二、控制器

public class InstructorController : Controller
{
    private SchoolContext db = new SchoolContext();

    public ActionResult Index(Int32? id, Int32? courseID)   // GET: /Instructor/
    {
        var viewModel = new InstructorIndexData();
        viewModel.Instructors = db.Instructors
            .Include(i => i.Courses.Select(c => c.Department))
            .OrderBy(i => i.LastName);
        if (id != null)
        {
            ViewBag.PersonID = id.Value;
            viewModel.Courses = viewModel.Instructors.Where(i => i.PersonID == id.Value).Single().Courses;
        }
        if (courseID != null)
        {
            ViewBag.CourseID = courseID.Value;
            var selectedCourse = viewModel.Courses.Where(x => x.CourseID == courseID).Single();
            db.Entry(selectedCourse).Collection(x => x.Enrollments).Load();
            foreach (Enrollment enrollment in selectedCourse.Enrollments)
            {
                db.Entry(enrollment).Reference(x => x.Student).Load();
            }
            viewModel.Enrollments = selectedCourse.Enrollments;
        }
        return View(viewModel);
    }

    public ViewResult Details(int id)  // GET: /Instructor/Details/5
    {
        Instructor instructor = db.Instructors.Find(id);
        return View(instructor);
    }

    public ActionResult Create()  // GET: /Instructor/Create
    {
        ViewBag.PersonID = new SelectList(db.OfficeAssignments, "PersonID", "Location");
        return View();
    }

    [HttpPost]
    public ActionResult Create(Instructor instructor) // POST: /Instructor/Create
    {
        if (ModelState.IsValid)
        {
            db.Instructors.Add(instructor);
            db.SaveChanges();
            return RedirectToAction("Index");
        }
        ViewBag.PersonID = new SelectList(db.OfficeAssignments, "PersonID", "Location", instructor.PersonID);
        return View(instructor);
    }

    public ActionResult Edit(int id) // GET: /Instructor/Edit/5
    {
        Instructor instructor = db.Instructors
            .Include(i => i.Courses)
            .Where(i => i.PersonID == id)
            .Single();
        PopulateAssignedCourseData(instructor);
        return View(instructor);
    }

    private void PopulateAssignedCourseData(Instructor instructor)
    {
        var allCourses = db.Courses;
        var instructorCourses = new HashSet<int>(instructor.Courses.Select(c => c.CourseID));
        var viewModel = new List<AssignedCourseData>();
        foreach (var course in allCourses)
        {
            viewModel.Add(new AssignedCourseData
            {
                CourseID = course.CourseID,
                Title = course.Title,
                Assigned = instructorCourses.Contains(course.CourseID)
            });
        }
        ViewBag.Courses = viewModel;
    }

    [HttpPost]
    public ActionResult Edit(int id, FormCollection formCollection, string[] selectedCourses) // POST: /Instructor/Edit/5
    {
        var instructorToUpdate = db.Instructors
            .Include(i => i.Courses)
            .Where(i => i.PersonID == id)
            .Single();
        if (TryUpdateModel(instructorToUpdate, "", null, new string[] { "Courses" }))
        {
            try
            {
                if (String.IsNullOrWhiteSpace(instructorToUpdate.OfficeAssignment.Location))
                {
                    instructorToUpdate.OfficeAssignment = null;
                }
                UpdateInstructorCourses(selectedCourses, instructorToUpdate);
                db.Entry(instructorToUpdate).State = EntityState.Modified;
                db.SaveChanges();
                return RedirectToAction("Index");
            }
            catch (DataException)
            {
                ModelState.AddModelError("", "Unable to save changes. Try again, and if the problem persists, see your system administrator.");
            }
        }
        PopulateAssignedCourseData(instructorToUpdate);
        return View(instructorToUpdate);
    }

    private void UpdateInstructorCourses(string[] selectedCourses, Instructor instructorToUpdate)
    {
        if (selectedCourses == null)
        {
            instructorToUpdate.Courses = new List<Course>();
            return;
        }
        var selectedCoursesHS = new HashSet<string>(selectedCourses);
        var instructorCourses = new HashSet<int>
            (instructorToUpdate.Courses.Select(c => c.CourseID));
        foreach (var course in db.Courses)
        {
            if (selectedCoursesHS.Contains(course.CourseID.ToString()))
            {
                if (!instructorCourses.Contains(course.CourseID))
                {
                    instructorToUpdate.Courses.Add(course);
                }
            }
            else
            {
                if (instructorCourses.Contains(course.CourseID))
                {
                    instructorToUpdate.Courses.Remove(course);
                }
            }
        }
    }

    public ActionResult Delete(int id)    // GET: /Instructor/Delete/5
    {
        Instructor instructor = db.Instructors.Find(id);
        return View(instructor);
    }

    [HttpPost, ActionName("Delete")]
    public ActionResult DeleteConfirmed(int id) // POST: /Instructor/Delete/5
    {
        Instructor instructor = db.Instructors.Find(id);
        db.Instructors.Remove(instructor);
        db.SaveChanges();
        return RedirectToAction("Index");
    }

    protected override void Dispose(bool disposing)
    {
        db.Dispose();
        base.Dispose(disposing);
    }
}

三、视图

Instructors:

@model ContosoUniversity.ViewModels.InstructorIndexData
@{ ViewBag.Title = "Instructors"; }
<h2> Instructors</h2>
<p> @Html.ActionLink("Create New", "Create")</p>
<table>
    <tr>  <th></th> <th>Last Name</th> <th>First Name</th><th>Hire Date</th><th>Office</th> <th>Courses</th> </tr>
    @foreach (var item in Model.Instructors)
    {
        string selectedRow = "";
        if (item.PersonID == ViewBag.PersonID)
        { selectedRow = "selectedrow"; }
        <tr class="@selectedRow" valign="top">
            <td>@Html.ActionLink("Select", "Index", new { id = item.PersonID })
| @Html.ActionLink("Edit", "Edit", new { id = item.PersonID })
| @Html.ActionLink("Details", "Details", new { id = item.PersonID })
| @Html.ActionLink("Delete", "Delete", new { id = item.PersonID }) </td>
            <td>@item.LastName </td>
            <td>@item.FirstMidName </td>
            <td>@String.Format("{0:d}", item.HireDate) </td>
            <td>
                @if (item.OfficeAssignment != null)
                { @item.OfficeAssignment.Location }
            </td>
            <td>
                @{ foreach (var course in item.Courses)
                   { @course.CourseID @:&nbsp; @course.Title <br />
                   } }
            </td>
        </tr>
    }
</table>
@if (Model.Courses != null)
{
    <h3>
        Courses Taught by Selected Instructor</h3>
    <table>
        <tr>   <th></th><th>ID</th> <th>Title</th>  <th>Department</th> </tr>
        @foreach (var item in Model.Courses)
        {
            string selectedRow = "";
            if (item.CourseID == ViewBag.CourseID)
            { selectedRow = "selectedrow"; }
            <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>
}
@if (Model.Enrollments != null)
{
    <h3> Students Enrolled in Selected Course</h3>
    <table>
        <tr>  <th>Name</th><th>Grade</th></tr>
        @foreach (var item in Model.Enrollments)
        {
            <tr>
                <td>@item.Student.FullName </td>
                <td>@Html.DisplayFor(modelItem => item.Grade) </td>
            </tr>
        }
    </table>
}

Edit:

@model ContosoUniversity.Models.Instructor
@{  ViewBag.Title = "Edit";}
<h2>Edit</h2>
<script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script>
@using (Html.BeginForm()) {
    @Html.ValidationSummary(true)
    <fieldset>
        <legend>Instructor</legend>
        @Html.HiddenFor(model => model.PersonID)
        <div class="editor-label">  @Html.LabelFor(model => model.LastName)
        </div>
        <div class="editor-field">  @Html.EditorFor(model => model.LastName)
           @Html.ValidationMessageFor(model => model.LastName)
        </div>
        <div class="editor-label">
            @Html.LabelFor(model => model.FirstMidName)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.FirstMidName)
            @Html.ValidationMessageFor(model => model.FirstMidName)
        </div>
        <div class="editor-label">
            @Html.LabelFor(model => model.HireDate)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.HireDate)
            @Html.ValidationMessageFor(model => model.HireDate)
        </div>
        <div class="editor-label">
            @Html.LabelFor(model => model.OfficeAssignment.Location)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.OfficeAssignment.Location)
            @Html.ValidationMessageFor(model => model.OfficeAssignment.Location)
        </div>
        <div class="editor-label">
            @Html.LabelFor(model => model.OfficeAssignment.Location)
        </div>
        <div class="editor-field">
            <table style="width: 100%">
                <tr>
                    @{
                        int cnt = ;
                        List<ContosoUniversity.ViewModels.AssignedCourseData> courses = ViewBag.Courses;
                        foreach (var course in courses) {
                            if (cnt++ %  == ) {
                                @:  </tr> <tr>
                            }
                            @: <td>
                                <input type="checkbox"
                                       name="selectedCourses"
                                       value="@course.CourseID"
                                       @(Html.Raw(course.Assigned ? "checked=\"checked\"" : "")) />
                                @course.CourseID @:&nbsp; @course.Title
                            @:</td>
                        }
                        @: </tr>
                    }
            </table>
        </div>
        <p>
            <input type="submit" value="Save" />
        </p>
    </fieldset>
}
<div>
    @Html.ActionLink("Back to List", "Index")
</div>