Object reference not set to an instance of an object

Question

I've returned all of my Get and Post controllers. But still, I'm having this kind of error. What am I missing?

Controller:
public ActionResult Data()
{
Excel1 products = GetProducts();
ViewBag.Message = "";
return View(products);
}

    public void DownloadFile(String file)  
    {  
        try  
        {  
            String filename = file;  
            String filepath = Server.MapPath("~/UploadedFile/" + filename);  

            Response.Clear();  
            Response.ClearHeaders();  
            Response.ClearContent();  
            Response.AddHeader("Content-Disposition", "attachment; filename=" + filename);  
            Response.Flush();  

            Response.TransmitFile(filepath);  
            Response.End();  
            // HttpContext.ApplicationInstance.CompleteRequest();  
            ViewBag.Message = "";  
        }  
        catch (Exception ex)  
        {  
            ViewBag.Message = ex.Message.ToString();  
        }  


    }  

    [HttpPost]  
    public ActionResult Data(Excel1 obj)  
    {  
        try  
        {  
            string strDateTime = System.DateTime.Now.ToString("ddMMyyyyHHMMss");  
            string finalPath = "\\UploadedFile\\" + strDateTime + obj.UploadFile.FileName;  

            obj.UploadFile.SaveAs(Server.MapPath("~") + finalPath);  
            obj.FilePath = strDateTime + obj.UploadFile.FileName;  
            ViewBag.Message = SaveToDB(obj);  
        }  
        catch (Exception ex)  
        {  
            ViewBag.Message = ex.Message.ToString();  
        }  

         

        Excel1 products = GetProducts();  
        return View(products);  

    }  

    public string SaveToDB(Excel1 obj)  
    {  
        try  
        {  
            con = new SqlConnection(connectionString);  
            cmd = new SqlCommand();  
            con.Open();  
            cmd.Connection = con;  
            cmd.CommandType = System.Data.CommandType.StoredProcedure;  
            cmd.CommandText = "sp_AddFiles";  
            cmd.Parameters.AddWithValue("@FileN", obj.FileN);  
            cmd.Parameters.AddWithValue("@FilePath", obj.FilePath);  
            cmd.ExecuteNonQuery();  

            cmd.Dispose();  
            con.Dispose();  
            con.Close();  

            return "Saved Successfully";  
        }  
        catch (Exception ex)  
        {  
            return ex.Message.ToString();  
        }  

    }  


    public Excel1 GetProducts() //method   
    {  
        Excel1 products = new Excel1();  
        try  
        {  
            con = new SqlConnection(connectionString);  
            cmd = new SqlCommand("Select * from tblFiles", con);  
            con.Open();  
            adapter = new SqlDataAdapter(cmd);  
            DataTable dt = new DataTable();  
            adapter.Fill(dt);  

            adapter.Dispose();  
            cmd.Dispose();  
            con.Close();  

            products.lstExcel = new List<Excel1>();  

            foreach (DataRow dr in dt.Rows)  
            {  
                products.lstExcel.Add(new Excel1  
                {  
                    FileN = dr["FileN"].ToString(),  
                    FilePath = dr["FilePath"].ToString()  
                });  
            }  

        }  
        catch (Exception ex)  
        {  
            adapter.Dispose();  
            cmd.Dispose();  
            con.Close();  
        }  

        if (products == null || products.lstExcel == null || products.lstExcel.Count == 0)  
        {  
            products = new Excel1();  
            products.lstExcel = new List<Excel1>();  
        }  

        return products;  
    }  
}  

Answer 1

Hi @JUAN MIGUEL C. NIETO ,
I tested your controller code and it works fine. Based on your current information, it is not clear where your problem is.
I wrote a working example based on your current code, you can check it yourself, where is the problem.
Model

 public class Excel1  
    {         
        public int ID { get; set; }  
        public string FileN { get; set; }  
        public string FilePath { get; set; }  
        public List<Excel1> lstExcel { get; set; }  
  
    }  

Data.cshtml

@model WebApplication5.Models.Excel1  
<h2>Data</h2>  
@foreach (var products in Model.lstExcel)  
{  
<h3><u>@products.FileN</u></h3>  
}  

Controller

public ActionResult Data()  
        {  
            Excel1 products = GetProducts();  
            ViewBag.Message = "";  
            return View(products);  
        }  
        [HttpPost]  
        public ActionResult Data(Excel1 obj)  
  
        {  
            Excel1 products = GetProducts();  
            return View(products);  
        }  

Best regards,
Lan Huang

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Answer 2

Answer 3

the error says Model is null, meaning the controller passed a null model to the view. debug the controller that calls this view.