.NET Core MVC] EF Core - 6.related data CRUD

related data CRUD를 구현하기 위해, 아래 view파일을 포함한 CRUD 기능에 필요한 코드를 작성해보자. 

 

Index.cshtml

Create.cshtml

Delete.cstml

우선 Course Entity를 확인해보자. 

Navigation Property가 3개가 있지만, 수정은 Department만 할 수 있도록 작성하였다. 

namespace WEB.Models;


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

        [StringLength(50, MinimumLength = 3)]
        public string Title { get; set; }

        [Range(0, 5)]
        public int Credits { get; set; }

        public int DepartmentID { get; set; }

        //Navigation Property
        public Department? Department { get; set; }
        public ICollection<Enrollment>? Enrollments { get; set; }
        public ICollection<CourseAssignment>? CourseAssignments { get; set; }
}

CoursesController.cs

using System.Diagnostics;
using Microsoft.AspNetCore.Mvc;
using WEB.Data;
using WEB.Models;
using WEB.Models.SchoolViewModels;
using Microsoft.EntityFrameworkCore;
using Microsoft.AspNetCore.Mvc.Rendering;


namespace WEB.Controllers;


public class CoursesController : Controller
{
    private readonly ILogger<HomeController> _logger;
    private readonly SchoolContext _context;


    public CoursesController(SchoolContext context, ILogger<HomeController> logger)
    {
        _logger = logger;
        _context = context;
    }


    public async Task<IActionResult> Index()
    {
        var courses = _context.Courses
            .Include(c => c.Department)
            .AsNoTracking();


        return View(await courses.ToListAsync());
    }


    public IActionResult Create()
    {
        PopulateDepartmentsDropDownList();
        return View();
    }


    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Create([Bind("CourseID,Credits,DepartmentID,Title")] Course course)
    {
        if (ModelState.IsValid)
        {
            _context.Add(course);
            await _context.SaveChangesAsync();
            return RedirectToAction(nameof(Index));
        }
        PopulateDepartmentsDropDownList(course.DepartmentID);
        return View(course);
    }


    public async Task<IActionResult> Edit(int? id)
    {
        if (id == null)
        {
            return NotFound();
        }

        var course = await _context.Courses
            .AsNoTracking()
            .FirstOrDefaultAsync(m => m.CourseID == id);

        if (course == null)
        {
            return NotFound();
        }
        PopulateDepartmentsDropDownList(course.DepartmentID);
        return View(course);
    }


    [HttpPost, ActionName("Edit")]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> EditPost(int? id)
    {
        if (id == null)
        {
            return NotFound();
        }

        var courseToUpdate = await _context.Courses
            .FirstOrDefaultAsync(c => c.CourseID == id);


        if (await TryUpdateModelAsync<Course>(courseToUpdate,
            "",
            c => c.Credits, c => c.DepartmentID, c => c.Title))
        {
            try
            {
                await _context.SaveChangesAsync();
            }
            catch (DbUpdateException /* ex */)
            {
                //Log the error (uncomment ex variable name and write a log.)
                ModelState.AddModelError("", "Unable to save changes. " +
                    "Try again, and if the problem persists, " +
                    "see your system administrator.");
            }
            return RedirectToAction(nameof(Index));
        }
        PopulateDepartmentsDropDownList(courseToUpdate.DepartmentID);
        return View(courseToUpdate);
    }


    private void PopulateDepartmentsDropDownList(object selectedDepartment = null)
    {
        var departmentsQuery = from d in _context.Departments
                                orderby d.Name
                                select d;

        ViewBag.DepartmentID = new SelectList(departmentsQuery.AsNoTracking(), "DepartmentID", "Name", selectedDepartment);
    }


    public async Task<IActionResult> Details(int? id)
    {
        if (id == null)
        {
            return NotFound();
        }

        var course = await _context.Courses
            .Include(c => c.Department)
            .AsNoTracking()
            .FirstOrDefaultAsync(m => m.CourseID == id);
       
        if (course == null)
        {
            return NotFound();
        }

        return View(course);
    }


    public async Task<ActionResult> Delete(int? id)
    {
        if (id == null)
        {
            return NotFound();
        }

        var course = await _context.Courses
            .Include(c => c.Department)
            .AsNoTracking()
            .FirstOrDefaultAsync(m => m.CourseID == id);
        if (course == null)
        {
            return NotFound();
        }
        return View(course);
    }


    [HttpPost, ActionName("Delete")]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> DeleteConfirmed(int id)
    {
        var course = await _context.Courses.FindAsync(id);
        if (course == null)
        {
            return NotFound();
        }
        _context.Courses.Remove(course);
        await _context.SaveChangesAsync();
        return RedirectToAction(nameof(Index));
    }

}

Create.cshtml

@model WEB.Models.Course

@{
    ViewData["Title"] = "Create";
}

<h1>Create</h1>

<h4>Course</h4>
<hr />
<div class="row">
    <div class="col-md-4">
        <form asp-action="Create">
            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
            <div class="form-group">
                <label asp-for="CourseID" class="control-label"></label>
                <input asp-for="CourseID" class="form-control" />
                <span asp-validation-for="CourseID" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Title" class="control-label"></label>
                <input asp-for="Title" class="form-control" />
                <span asp-validation-for="Title" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Credits" class="control-label"></label>
                <input asp-for="Credits" class="form-control" />
                <span asp-validation-for="Credits" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Department" class="control-label"></label>
                <select asp-for="DepartmentID" class="form-control" asp-items="ViewBag.DepartmentID">
                    <option value="">-- Select Department --</option>
                </select>
                <span asp-validation-for="DepartmentID" class="text-danger" />
            </div>
            <div class="form-group">
                <input type="submit" value="Create" class="btn btn-primary" />
            </div>
        </form>
    </div>
</div>


<div>
    <a asp-action="Index">Back to List</a>
</div>


@section Scripts {
    @{await Html.RenderPartialAsync("_ValidationScriptsPartial");}
}

Delete.cshtml

@model WEB.Models.Course


@{
    ViewData["Title"] = "Delete";
}


<h1>Delete</h1>


<h3>Are you sure you want to delete this?</h3>
<div>
    <h4>Course</h4>
    <hr />
    <dl class="row">
        <dt class="col-sm-2">
            @Html.DisplayNameFor(model => model.CourseID)
        </dt>
        <dd class="col-sm-10">
            @Html.DisplayFor(model => model.CourseID)
        </dd>
        <dt class="col-sm-2">
            @Html.DisplayNameFor(model => model.Title)
        </dt>
        <dd class="col-sm-10">
            @Html.DisplayFor(model => model.Title)
        </dd>
        <dt class="col-sm-2">
            @Html.DisplayNameFor(model => model.Credits)
        </dt>
        <dd class="col-sm-10">
            @Html.DisplayFor(model => model.Credits)
        </dd>
        <dt class="col-sm-2">
            @Html.DisplayNameFor(model => model.Department)
        </dt>
        <dd class="col-sm-10">
            @Html.DisplayFor(model => model.Department.DepartmentID)
        </dd>
    </dl>
   
    <form asp-action="Delete">
        <input type="hidden" asp-for="CourseID" />
        <input type="submit" value="Delete" class="btn btn-danger" /> |
        <a asp-action="Index">Back to List</a>
    </form>
</div>

Details.cshtml

@model WEB.Models.Course


@{
    ViewData["Title"] = "Details";
}


<h1>Details</h1>


<div>
    <h4>Course</h4>
    <hr />
    <dl class="row">
        <dt class="col-sm-2">
            @Html.DisplayNameFor(model => model.CourseID)
        </dt>
        <dd class="col-sm-10">
            @Html.DisplayFor(model => model.CourseID)
        </dd>
        <dt class="col-sm-2">
            @Html.DisplayNameFor(model => model.Title)
        </dt>
        <dd class="col-sm-10">
            @Html.DisplayFor(model => model.Title)
        </dd>
        <dt class="col-sm-2">
            @Html.DisplayNameFor(model => model.Credits)
        </dt>
        <dd class="col-sm-10">
            @Html.DisplayFor(model => model.Credits)
        </dd>
        <dt class="col-sm-2">
            @Html.DisplayNameFor(model => model.Department)
        </dt>
        <dd class="col-sm-10">
            @Html.DisplayFor(model => model.Department.DepartmentID)
        </dd>
    </dl>
</div>
<div>
    <a asp-action="Edit" asp-route-id="@Model.CourseID">Edit</a> |
    <a asp-action="Index">Back to List</a>
</div>

Edit.cshtml

@model WEB.Models.Course


@{
    ViewData["Title"] = "Edit";
}


<h1>Edit</h1>


<h4>Course</h4>
<hr />
<div class="row">
    <div class="col-md-4">
        <form asp-action="Edit">
            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
            <input type="hidden" asp-for="CourseID" />
            <div class="form-group">
                <label asp-for="CourseID" class="control-label"></label>
                <div>@Html.DisplayFor(model => model.CourseID)</div>
            </div>
            <div class="form-group">
                <label asp-for="Title" class="control-label"></label>
                <input asp-for="Title" class="form-control" />
                <span asp-validation-for="Title" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Credits" class="control-label"></label>
                <input asp-for="Credits" class="form-control" />
                <span asp-validation-for="Credits" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Department" class="control-label"></label>
                <select asp-for="DepartmentID" class="form-control" asp-items="ViewBag.DepartmentID">
                    <option value="">-- Select Department --</option>
                </select>
                <span asp-validation-for="DepartmentID" class="text-danger" />
            </div>
            <div class="form-group">
                <input type="submit" value="Save" class="btn btn-primary" />
            </div>
        </form>
    </div>
</div>


<div>
    <a asp-action="Index">Back to List</a>
</div>


@section Scripts {
    @{await Html.RenderPartialAsync("_ValidationScriptsPartial");}
}

Index.cshtml

@model IEnumerable<WEB.Models.Course>


@{
    ViewData["Title"] = "Courses";
}


<h2>Courses</h2>


<p>
    <a asp-action="Create">Create New</a>
</p>
<table class="table">
    <thead>
        <tr>
            <th>
                @Html.DisplayNameFor(model => model.CourseID)
            </th>
            <th>
                @Html.DisplayNameFor(model => model.Title)
            </th>
            <th>
                @Html.DisplayNameFor(model => model.Credits)
            </th>
            <th>
                @Html.DisplayNameFor(model => model.Department)
            </th>
            <th></th>
        </tr>
    </thead>
    <tbody>
        @foreach (var item in Model)
        {
            <tr>
                <td>
                    @Html.DisplayFor(modelItem => item.CourseID)
                </td>
                <td>
                    @Html.DisplayFor(modelItem => item.Title)
                </td>
                <td>
                    @Html.DisplayFor(modelItem => item.Credits)
                </td>
                <td>
                    @Html.DisplayFor(modelItem => item.Department.Name)
                </td>
                <td>
                    <a asp-action="Edit" asp-route-id="@item.CourseID">Edit</a> |
                    <a asp-action="Details" asp-route-id="@item.CourseID">Details</a> |
                    <a asp-action="Delete" asp-route-id="@item.CourseID">Delete</a>
                </td>
            </tr>
        }
    </tbody>
</table>