Another object reference not set... problem

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1.50/5 (2 votes)

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Im getting object reference not set to an instance of an object error when im trying to insert data from a dropdownlist in mvc... sombody pls help me to solve this error as im new to mvc...

C#

Model:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace Bioderma.Models
{
    public class ConsumerModel
    {
        public int id { get; set; }
        public string fname { get; set; }
        public string lname { get; set; }
        public SkinType SkinType { get; set; }
    }

    public partial class SkinType
    {
        public int id { get; set; }
        public string skin { get; set; }
    }
}

View:
@model Bioderma.Models.ConsumerModel

@{
    ViewBag.Title = "InsertConsumer";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<h2>InsertConsumer</h2>
<html>
    <body>
        <form method="post">
    First Name : @Html.TextBoxFor(ConsumerModel=>ConsumerModel.fname)<br />
    Last Name : @Html.TextBoxFor(ConsumerModel=>ConsumerModel.lname)<br />
    Skin Type:
            <select id="ddlskintype" name="skintype">
            <option id="" value="chooseitem">--Select--</option>
            @foreach(var item in ViewData["SkinType"] as List<Bioderma.Models.SkinType>)
                {
                    <option>@item.skin</option>
                }
            </select>
            <br />
<input type="submit" value="submit" name="Insert" />

 </form>
    </body>
</html>

Controller:

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using Bioderma.Models;
using System.Data;
using DataAccessLayer;
using Bioderma.Models.DAL;

namespace Bioderma.Controllers
{
    public class ConsumerController : Controller
    {
        //
        // GET: /Consumer/
        ClsConsumerDAL csDAL = new ClsConsumerDAL();

        public ActionResult Index()
        {
            return View();
        }

        public ActionResult InsertConsumer()
        {
            ViewData["SkinType"] = csDAL.GetSkinType();
            return View();
        }

        [HttpPost]
        public ActionResult InsertConsumer(ConsumerModel csmodel)
        {
            if (ModelState.IsValid)
            {
                int res = 0;
                ClsConsumerDAL csDAL = new ClsConsumerDAL();
                res = csDAL.InsertConsumerData(csmodel);
               
                if (res > 0)
                {
                    ViewData["res"] = "data saved";
                }
                else
                {
                    ViewData["res"] = "data saving failed";
                }
                ModelState.Clear(); //clearing model

                return View();
            }
            else
            {
                ModelState.AddModelError("", "cannot insert");
                return View();
            }
            return View();
        }
    }
}

ClsConsumerDAL file:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data;
using MySql.Data.MySqlClient;
using Bioderma.Models.DAL;
using DataAccessLayer;

namespace Bioderma.Models.DAL
{
    public class ClsConsumerDAL
    {
        MySqlDataAccessLayer mysqldal;
        public string CommandText = string.Empty;

        public ClsConsumerDAL()
        {
            mysqldal = new MySqlDataAccessLayer();
        }

        public int InsertConsumerData(ConsumerModel csmodel)
        {
            try
            {

                CommandText = "usp_InsertConsumerData";
                MySqlParameter[] mysqlparameters = new MySqlParameter[3];

                mysqlparameters[0] = new MySqlParameter("FName", MySqlDbType.String);
                mysqlparameters[0].Value = csmodel.fname.ToString();

                mysqlparameters[1] = new MySqlParameter("LName", MySqlDbType.String);
                mysqlparameters[1].Value = csmodel.lname.ToString();

               
                mysqlparameters[2] = new MySqlParameter("SkinID", MySqlDbType.Int32);
                mysqlparameters[2].Value = Convert.ToInt32(csmodel.SkinType.id);

                return mysqldal.ExecuteQuery(CommandText, CommandType.StoredProcedure, mysqlparameters);
            }
            catch(Exception ex)
            {
                throw ex;
            }
        }

        public List<SkinType> GetSkinType()
        {
            List<SkinType> SkinType = new List<SkinType>();

            CommandText = "usp_GetSkinType";

            DataSet ds = mysqldal.ExecuteDataSet(CommandText);

            SkinType = ds.Tables[0].AsEnumerable().Select(data => new SkinType() { id = (int)data["ID"], skin = (string)data["Skin"] }).ToList();

            return SkinType;

        }

    }
}

Posted 22-Jul-14 2:50am

usha C

Updated 22-Jul-14 4:56am

Christian Amado

v3

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Comments

[no name] 22-Jul-14 8:54am

You get that error just like everyone else get that same error. You are trying to use the methods or properties of a class that has not been instantiated. Debug your code to find it.

Richard MacCutchan 22-Jul-14 9:17am

This error is nothing to do with MVC it is basic object oriented programming. And if you do not understnd the basics you are wasting your time trying to use an advanced framework.

Christian Amado 22-Jul-14 10:57am

You must verify that every variable isn't null before use it.

Maciej Los 22-Jul-14 11:01am

Which line?

Sergey Alexandrovich Kryukov 22-Jul-14 12:01pm

My usual answer fits this case, too. Do they ever look through CodeProject (or anything else on the Web) for available answers?
:-(.
—SA

Maciej Los 22-Jul-14 12:04pm

Nope... ;(

Sergey Alexandrovich Kryukov 22-Jul-14 12:10pm

Did you click on ":-(" above?
—SA

Maciej Los 22-Jul-14 12:14pm

No, i'll do.

Maciej Los 22-Jul-14 12:16pm

I saw it earlier, when i visited your website.

Sergey Alexandrovich Kryukov 22-Jul-14 12:21pm

:-) :-)

Maciej Los 22-Jul-14 12:21pm

BTW: my favorite photo is Moose from this album
I bet you know why... ;)

Sergey Alexandrovich Kryukov 22-Jul-14 12:25pm

It's shame that I have much newer and more interesting photo, even of much better technical quality and other things, and I never put them on site...

However, I never took another picture of a moose in the wild like that one. The silly guy stayed by the road at full day lite (usually they appear closer to 10 PM and later when there is no light) for half an hour or so and let me to spend a whole film on it (can you believe that it was the film?)...

—SA

Maciej Los 22-Jul-14 12:29pm

Not shame, it's called: NET - "Not Enough Time" ;)
Do you know what means: ".NET" statement? "Definitely Not Enough Time" ;)

Can you share the film (or it's part)? I saw wild animals in its natural environment (like European bison, boar, common viper, etc.), but i never saw my family ;)

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Sergey Alexandrovich Kryukov · Answer 1 · 2014-07-22T05:46:00

You did not show where the exception with the message "Object reference not set to an instance of an object" is thrown.

Not to worry. This is one of the very easiest cases to detect and fix. It simply means that some member/variable of some reference type is dereferenced by using and of its instance (non-static) members, which requires this member/variable to be non-null, but in fact it appears to be null. Simply execute it under debugger, it will stop the execution where the exception is thrown. Put a break point on that line, restart the application and come to this point again. Evaluate all references involved in next line and see which one is null while it needs to be not null. After you figure this out, fix the code: either make sure the member/variable is properly initialized to a non-null reference, or check it for null and, in case of null, do something else.

Please see also: want to display next record on button click. but got an error in if condition of next record function "object reference not set to an instance of an object"[^].

Sometimes, you cannot do it under debugger, by one or another reason. One really nasty case is when the problem is only manifested if software is built when debug information is not available. In this case, you have to use the harder way. First, you need to make sure that you never block propagation of exceptions by handling them silently (this is a crime of developers against themselves, yet very usual). The you need to catch absolutely all exceptions on the very top stack frame of each thread. You can do it if you handle the exceptions of the type System.Exception. In the handler, you need to log all the exception information, especially the System.Exception.StackTrace:
http://msdn.microsoft.com/en-us/library/system.exception.aspx[^],
http://msdn.microsoft.com/en-us/library/system.exception.stacktrace.aspx[^].

The stack trace is just a string showing the full path of exception propagation from the throw statement to the handler. By reading it, you can always find ends. For logging, it's the best (in most cases) to use the class System.Diagnostics.EventLog:
http://msdn.microsoft.com/en-us/library/system.diagnostics.eventlog.aspx[^].

Good luck,

—SA