(C# ASP.NET Core) Deleting Records from a Database with EF Core

Quick outline of the EF Core steps

Step 1: Get the item by using its primary key id.

// query the DbSet for the item to delete 
var prod = await _ctx.Products.FindAsync(id);

Step 2: Mark the item for removal.

// mark for removal from DbSet 
_ctx.Products.Remove(prod);

Step 3: Save changes to cause the deletion

// cause the deletion 
await _ctx.SaveChangesAsync();

Video Explanation with a Working Example

Please watch the following youtube video:

How to add anchor link buttons for delete

Tag helpers are used to connect an anchor link button to a function in the backing class, and also to specify any parameters for that function.

The following code uses the attribute asp-page-handler to connect the click event to a function called "Delete" in the backing class, and asp-route-id to specify the parameter id. Nothing else needs to be done - no javascript, nothing else needs to be done - everything is handled by asp.net core.

// route-id is used to pass the primary key id 
// page-handler is used to specify the name of the function 
// that will cause deletion in the backing class 

<a asp-route-id="@prod.ID" asp-page-handler="Delete">Delete</a>

// NOTE: these links are added in a foreach 
// loop as explained in the example next 

Pre-requisites for this Tutorial

You should already have completed the tutorial on display of data - (C# ASP.NET Core) Displaying Data and OnGetAsync

Step 1 of 2: Index.cshtml Razor Page
(see the linked video for details)

Following is the completed file

@page "{handler?}/{id?}"

@model Modular.Pages.IndexModel

@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

<h1>Display of Data</h1>

@foreach (var prod in Model.Products)
{
  <div>
    @prod.Name 
    |
    <a asp-route-id="@prod.ID" asp-page-handler="Delete">Delete</a>
  </div>

  <hr />
}

Step 2 of 2: Index.cshtml.cs backing class file
(see the linked video for details)

Following is the code for the backing class. Notice the handler Delete is prefixed as OnGetDelete

using DBaseCon;

using Microsoft.AspNetCore.Mvc;

using Microsoft.AspNetCore.Mvc.RazorPages;

using Microsoft.EntityFrameworkCore;

using System.Collections.Generic;

using System.Threading.Tasks;

namespace Modular.Pages
{

  public class IndexModel : PageModel
  {

    private readonly ProductContext _ctx;

    // dependency injection of the ProductContext 
    public IndexModel(ProductContext ctx)
    {

      _ctx = ctx;

    }

    // using System.Collections.Generic 
    // for Display 
    public IList<Product> Products { get; set; }

    // get the records when the page loads 
    public async void OnGetAsync()
    {

      // using Microsoft.EntityFrameworkCore; 

      Products = await _ctx.Products.ToListAsync();

    }

    // Delete the record Sql DELETE 
    public async Task<IActionResult> OnGetDelete(int? id)
    {

      if (null == id)
      {

        // sends 404 error 
        return NotFound();

      }

      // query the DbSet for the item to delete 
      var prod = await _ctx.Products.FindAsync(id);

      // mark from removal from DbSet 
      _ctx.Products.Remove(prod);

      // cause the deletion 
      await _ctx.SaveChangesAsync();

      return RedirectToPage();

    }

  }

}