Cascading DropDownList in .NET Core

Question

I am trying to use the tutorial linked below but adapting it to my SQL DB for States, Districts, Schools tables that I already have in place. I am new to .NET Core MVC and do not understand the error nor how to debug it. Any help appreciated.

Cascading DropDownList In .NET Core

Error: Microsoft.Data.SqlClient.SqlException: 'Invalid object name 'State'.' This exception was originally thrown at this call stack: [External Code] CascadingExample.Controllers.HomeController.Index() in HomeController.cs

        [External Code]

using CascadingExample.Entities;
using CascadingExample.Models;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;

namespace CascadingExample.Controllers
{
    public class HomeController : Controller
    {
        private readonly ILogger<HomeController> _logger;
        private readonly MyDBContent _con;

        public HomeController(ILogger<HomeController> logger, MyDBContent con)
        {
            _logger = logger;
            _con = con;
        }

        public IActionResult Index()
        {
            ViewBag.StateList = _con.State.ToList();
            return View();
        }
            

        public JsonResult GetDistrictByStateID(int statedID)
        {
            var data = _con.District.Where(x => x.StateID == statedID).ToList();
            return Json(data);
        }


        public IActionResult Privacy()
        {
            return View();
        }


        [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
        public IActionResult Error()
        {
            return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
        }
    }
}

Answer 1

The error means the table named 'State' has not created or the Database you are referring has not created

I checked the dbcontext in your tutorial,and it will not create the table"State".

public class MyDBContent:DbContext
    {
        private IConfigurationRoot _config;
        public MyDBContent(IConfigurationRoot config, DbContextOptions options) : base(options)
        {
            _config = config;
        }
        public DbSet<Category> Category { get; set; }
        public DbSet<SubCategory> SubCategory { get; set; }

 

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            base.OnConfiguring(optionsBuilder);
            optionsBuilder.UseSqlServer(_config["ConnectionStrings:DefaultConnection"]);//connection string get by appsetting.json
        }
    }

You need to add these codes:

public DbSet<State> State { get; set; }