ASP.NET - Delete row from database using a cshtml webpage

Question

I am having trouble deleting a row by Id. I display every row of my DB in a table and next to every row I have a button that should be used for deleting that specific row in the DB.

It should delete only the row with that specific id, but what actually happens, is that I don't even press the button, but when accessing the page - the whole content of the DB gets deleted.

What did I do wrong?

Here's my code so far:

Controller:

public class AdminController : BaseController
{
    private UserContext context;

    public AdminController()
    {
        context = new UserContext();
    }

    public void delete_by_id(int id)
    {
        context.Users.Where(x => x.Id == id).DeleteFromQuery();
    }

    // GET: Admin
    [AdminMod]
    public ActionResult Index()
    {
        SessionStatus();
        if ((string)System.Web.HttpContext.Current.Session["LoginStatus"] != "login")
        {
            return RedirectToAction("Index", "Login");
        }
        var user = System.Web.HttpContext.Current.GetMySessionObject();
        UserData u = new UserData
        {
            Username = user.Username,
            Level = user.Level,
        };


        return View("Index", u);
    }
}

UserContext:

public class UserContext : DbContext
{
    public UserContext() :
        base("name=WebApplication1")
    {

    }

    public virtual DbSet<UDbTable> Users { get; set; }
}

Index.cshtml:

@using WebApplication1.Controllers
@using WebApplication1.Domain.Enums
@using WebApplication1.Extension
@using WebMatrix.Data


@{
    ViewBag.Title = "Admin";
    Layout = "~/Views/Shared/_Layout.cshtml";
    var db = Database.Open("WebApplication1");
    var selectQueryString = "SELECT * FROM UDbTables ORDER BY Id";

}

<script>
    function refreshPage() {
        window.location.reload();
    }
</script>

<div class="container" style="margin-top: 1%;">
    <h1>AdminPage</h1>
    <table class="table table-bordered">
        <thead>
        <tr>
            <th scope="col">#Id</th>
            <th scope="col">Username</th>
            <th scope="col">Email</th>
            <th scope="col">Level</th>
            <th scope="col"></th>
        </tr>
        </thead>
        <tbody>
        @foreach (var row in db.Query(selectQueryString))
        {
            <tr>
                <th scope="row">#@row.Id</th>
                <td>@row.Username</td>
                <td>@row.Email</td>
                @{
                    if (@row.Level == 0)
                    {
                        <td>User</td>
                    }
                    else if (row.Level == 1)
                    {
                        <td>Premium</td>
                    }
                    else
                    {
                        <td>Admin</td>
                    }
                }
                <td>
                    <button type="button" data-bs-togle="modal" data-bs-target="#IdModal" class="btn btn-danger" data-toggle="tooltip" data-placement="right" title="Delete User" id="@row.Id" onclick ="refreshPage()">
                        @{
                            var smth = new AdminController();
                            smth.delete_by_id(row.Id); //HERE IS WHERE I CALL THE QUERY
                        }
                        <i class="fas fa-trash"></i>
                    </button>
                </td>
            </tr>

          }
        </tbody>
    </table>
</div>

Here I have the proof that the correct Id is assigned to each row:

Code provided on a .cshtml page between @{...} is executed server side . Your smth.delete_by_id(row.Id) is executed before the page is even loaded, and that for each row. — Jeroen Verfaillie
– Jeroen Verfaillie, Commented Apr 29, 2022 at 12:55
from an MVC point of view you are doing many things wrong. I suggest you to work through some tutorials for example here learn.microsoft.com/en-us/aspnet/core/tutorials/first-mvc-app/… — gsharp
– gsharp, Commented May 1, 2022 at 8:37

Yong Shun · Accepted Answer · 2022-05-01 08:24:23Z

1

Create a form for submitting a POST request for delete action.

<td>
    @using (Html.BeginForm("Delete", "Admin", new { id = row.Id }, FormMethod.Post))
    {
        <button type="submit" data-bs-togle="modal" data-bs-target="#IdModal" class="btn btn-danger" data-toggle="tooltip" data-placement="right" title="Delete User" id="@row.Id">
            <i class="fas fa-trash"></i>
        </button>
    }
</td>

In AdminController, you need a Delete with [HttpPost] method to perform the delete operation and then return View.

public class AdminController : BaseController
{
    ...

    [HttpPost]
    public ActionResult Delete(int id)
    {
        delete_by_id(id);

        // Return desired view
        return Index();
    }
}

answered May 1, 2022 at 8:24

Yong Shun

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