[Solved] ASP.Net Core MVC DropDownList Error: object reference not set to an instance of an object

Hi Hjalmaar,

Please refer below sample.

Database

For this example I have used database named FruitsDB which has a table named Fruits with the schema as follows.

Model

FruitModel

public class FruitModel
{
    [Key]
    public int FruitId { get; set; }
    public string FruitName { get; set; }
}

 FruitListModel

public class FruitList
{
    public List<SelectListItem> FruitsLists { get; set; }
}

Namespaces 

using Bind_DropDownList_Core_Model.Model;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Rendering;
using System.Collections.Generic;

Controller

public class HomeController : Controller
{
    private DBCtx Context { get; }
    public HomeController(DBCtx _context)
    {
        this.Context = _context;
    }

    public IActionResult Index()
    {
        FruitList fruits = new FruitList()
        {
            FruitsLists = PopulateFruits()
        };
        return View(fruits);
    }

    private List<SelectListItem> PopulateFruits()
    {
        List<SelectListItem> fruits = new List<SelectListItem>();
        foreach (FruitModel fruit in this.Context.Fruits.ToList())
        {
            fruits.Add(new SelectListItem { Text = fruit.FruitName, Value = fruit.FruitId.ToString() });
        }

        return fruits;
    }
}

 View

<select id="ddlFruits" asp-items="@Model.FruitsLists">
    <option value="0">Please select</option>
</select>

Screenshot