Getting the error "object reference not set to an instance of an object".

Question

1.00/5 (1 vote)

See more:

Im providing the code..Please solve the error. Waiting for the solution.

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;


public partial class Default_login_trial : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void btnLogin_Click(object sender, EventArgs e)
    {
         DataTable dt = new DataTable();
        SqlDataAdapter adp = new SqlDataAdapter();    
        try
        {
            SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["conStr"].ConnectionString);
            SqlCommand cmd = new SqlCommand("Login_Check_Sp", con);
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddWithValue("@username", txtUserName.Text.Trim());
            cmd.Parameters.AddWithValue("@pwd", txtPwd.Text.Trim());
            adp.SelectCommand = cmd;          
            adp.Fill(dt);
            cmd.Dispose();
            if (dt.Rows.Count > 0)
            {
                lblStatus.Text = "Login Successfull";
                
            }
            else
            {
                lblStatus.Text = "Wrong Username/Password";
                
            }  
        }
        catch (Exception ex)
        {
            ScriptManager.RegisterStartupScript(this, this.GetType(), "Message", "alert('Oops!! following error occured : " + ex.Message.ToString() + "');", true);
        
        }
        finally
        {
            dt.Clear();
            dt.Dispose();
            adp.Dispose();         
        }     
    }
}

Posted 11-Dec-14 19:41pm

Member 11305027

Updated 11-Dec-14 20:47pm

Rajesh waran

v2

Add a Solution

Comments

syed shanu 12-Dec-14 1:52am

Check with break point and tell us in which line do you get the error

syed shanu 12-Dec-14 1:56am

Check my article realted to your program.
http://www.codeproject.com/Articles/852205/Insert-select-update-delete-in-asp-net-with-Simple

Member 11305027 12-Dec-14 2:10am

@syed Shanu : Sircan u please let me know wats the solution for my question.?

syed shanu 12-Dec-14 2:16am

Chk my solution hope that will help you

Rajesh waran 12-Dec-14 2:45am

Make a break point and debug your code then find where you are struck with that "msg" and tell us .bcoz we can't find your screen.

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

syed shanu · Answer 1 · 2014-12-11T20:15:00

Solution 2

Try like this

C#

protected void btnLogin_Click(object sender, EventArgs e)
  {

      DataSet ds = new DataSet();
      DataTable dt = new DataTable();
      SqlDataAdapter adp = new SqlDataAdapter();

      using (SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["conStr"].ConnectionString))
      {
          SqlCommand cmd = new SqlCommand("Login_Check_Sp", conn);
          cmd.Parameters.AddWithValue("@username", txtUserName.Text.Trim());
          cmd.Parameters.AddWithValue("@pwd", txtPwd.Text.Trim());

          cmd.CommandType = CommandType.StoredProcedure;

          SqlDataAdapter da = new SqlDataAdapter();
          da.SelectCommand = cmd;
          da.Fill(ds);
          dt = ds.Tables[0];

          if (dt.Rows.Count > 0)
          {
              lblStatus.Text = "Login Successfull";

          }
          else
          {
              lblStatus.Text = "Wrong Username/Password";

          }
      }



  }

Try the above code and still if you have error .
Debug aand using break point check where you get the error.
There might be many reason as connection might not established.
here is few link which explains how to use break point in visual studio.

http://www.tutorialspoint.com/asp.net/asp.net_debugging.htm[^]

https://www.youtube.com/watch?v=k1EQndVmlOc[^]

Posted 11-Dec-14 20:15pm

syed shanu

Updated 11-Dec-14 20:42pm

v2

Comments

Member 11305027 12-Dec-14 2:25am

Sir this is also nt working.

syed shanu 12-Dec-14 2:26am

I msg you to check with break point and in which line do you get the error.

Member 11305027 12-Dec-14 2:27am

Can u tell me how to use breakpoint in the program as i have never use breakpoint.??

syed shanu 12-Dec-14 2:43am

I have updated my solution check it

Member 11305027 12-Dec-14 4:37am

I tried the code dat u gave me.then also error coming.The error coming is in the line
da.Fill(ds);
as SQLException was unhandled by user code. Could not find stored procedure 'Login_Check_Sp'.

Could not find stored procedure 'Login_Check_Sp'.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Data.SqlClient.SqlException: Could not find stored procedure 'Login_Check_Sp'.

Source Error:

Line 32: SqlDataAdapter da = new SqlDataAdapter();
Line 33: da.SelectCommand = cmd;
Line 34: da.Fill(ds);
Line 35: dt = ds.Tables[0];
Line 36:

The Stored procedure i wrote is as follows :

CREATE PROCEDURE Login_Check_Sp
-- Add the parameters for the stored procedure here
@username varchar(100),
@pwd varchar(100)
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
where UserName COLLATE Latin1_general_CS_AS=@username
and [Password] COLLATE Latin1_general_CS_AS=@pwd
-- Insert statements for procedure here
SELECT * FROM Login_Tb WHERE Username =@username AND password =@pwd
END
GO

Please solve the error.

Member 11305027 12-Dec-14 5:17am

Thank you for the solution.Problem solved

syed shanu 12-Dec-14 5:32am

Your code also works fine .yes it was only due to SP missing .In futuer use break point you can find your solution from there.