Error on registration form when submitting a new user.

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I have a form that registraters a new user. When the user puts in their email address and password then click submit I get an error for: System.NullReferenceException {"Object reference not set to an instance of an object."}. What is this error and how can I fix it? The error happens on line 29. that line is:

C#

int temp = Convert.ToInt32(userExist.ExecuteScalar().ToString());

Here is all of the code for the form:

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.SqlClient;
using System.Configuration;
using System.Web.Security;
using System.Security.Cryptography;

public partial class SubmitPage : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (IsPostBack)
        {
            SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["PasswordConnectionString"].ConnectionString);
            con.Open();

            string cmdStr = "Select INST_ID, EmailAddress from TableSecurity where EmailAddress='" + TextBoxEA.Text + "'";
            string cmdStr2 = "Select INST_ID, EmailAddress from TableCEO where EmailAddress ='" + TextBoxEA.Text + "'";
            string cmdStr3 = "Select INST_ID, EmailAddress from TableIALO where EmailAddress ='" + TextBoxEA.Text + "'";
            
            SqlCommand userExist = new SqlCommand(cmdStr, con);
            SqlCommand cmd = new SqlCommand("select INST_ID, EmailAddress from TableSecurity", con);
            SqlCommand cmd2 = new SqlCommand("select INST_ID, EmailAddress from TableCEO", con);
            SqlCommand cmd3 = new SqlCommand("select INST_ID, EmailAddress from TableIALO", con);
            int temp = Convert.ToInt32(userExist.ExecuteScalar().ToString());
            if (temp == 1)

                Response.Write("User Name Already Exist!!!<br /> Please Choose Another User Name.");
        }



    }

    protected void Submit_Click(object sender, EventArgs e)
    {
        SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["PasswordConnectionString"].ConnectionString);
        con.Open();

        string chkUser = "select INST_ID, EmailAddress from TableCEO where EmailAddress'" + TextBoxEA.Text + "";
        chkUser = "select INST_ID, EmailAddress from TableIALO where EmailAddress'" + TextBoxPW.Text + "";
        SqlCommand chkUsercmd = new SqlCommand(chkUser, con);


        string insCmd = "Insert into TableSecurity (INST_ID, EmailAddress, Password) values (@INST_ID, @EmailAddress, @Password)";
        SqlCommand insertUser = new SqlCommand(insCmd, con);
        insertUser.Parameters.AddWithValue("@EmailAddress", TextBoxEA.Text);
        insertUser.Parameters.AddWithValue("@Password", TextBoxPW.Text);
        


        try
        {
            insertUser.ExecuteNonQuery();
            con.Close();
            Response.Redirect("Login.aspx");
        }
        catch (Exception er)
        {
            Response.Write("An error occurred: " + er.Message);
        }
        finally
        {
        }
    }
    
}

Posted 15-Oct-13 4:28am

Computer Wiz99

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2 solutions

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MayurDighe · Accepted Answer · 2013-10-15T04:50:00

Solution 1

You are Good Programmer....

But..there is One thing I noticed.... that....you just missed a single line to add into your code while passing Parameters to the SqlCommand Object.

C#

//Your Code....

string insCmd = "Insert into TableSecurity (INST_ID, EmailAddress, Password) values (@INST_ID, @EmailAddress, @Password)";
SqlCommand insertUser = new SqlCommand(insCmd, con);



//Here is the Solution--
//Add @INST_ID to SQLCommand

        insertUser.Parameters.AddWithValue("@INST_ID", 'TextBoxName.Text');

//--------------------

      //Your Code...
        insertUser.Parameters.AddWithValue("@EmailAddress", TextBoxEA.Text);
        insertUser.Parameters.AddWithValue("@Password", TextBoxPW.Text);

Posted 15-Oct-13 4:50am

MayurDighe

Updated 15-Oct-13 4:51am

v2

Comments

Computer Wiz99 15-Oct-13 11:17am

Thanks for the compliment MayurDighe. Even the best of us will miss something every once in a while. It just takes another pair of eyes to look at it again.

There is only one problem with the code you gave me. The @INST_ID does not have a textbox to enter that field. I am getting that data from the database. Is there a different way for me to get the INST_ID from one table to another depending on the email address of that user?

thatraja 15-Oct-13 11:25am

Just pass the value which has INST_ID value.
if variable strINST_ID has value then write like below.
insertUser.Parameters.AddWithValue("@INST_ID", strINST_ID);

Computer Wiz99 15-Oct-13 11:39am

Ok. This is TableSecurity lay out.

INST_ID
EmailAddress
Password
accessLevel

All of my other Tables have almost the samething with added data fields. All of my Tables has INST_ID in them because of the data that matches the user. I have all of the users profile in CEO Table that starts with the INST_ID. I am trying to get that ID to the security table where the password and emailaddress are.

MayurDighe · Accepted Answer · 2013-10-15T05:25:00

Solution 2

Yup....

Fetch the value of INST_ID from required table...and just assign it to the local variable ...then pass its value instead of Textbox into SqlCommand object

C#

int tempID='code for retrieving unique INST_ID'

insertUser.Parameters.AddWithValue("@INST_ID", tempID);

Posted 15-Oct-13 5:25am

MayurDighe