How to solve this-the connectionstring property has not been initialized.

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I am trying to code for login in asp.net web application form. using sql data base.
i am getting error this- "The ConnectionString property has not been initialized."
Here i get error dialogbox extension-

con = new SqlConnection(str);
           con.Open();
           str = "Select count(*) from admin where UserName='" + (TextBox1.Text) + "'
            and Password='" + (TextBox2.Text) + "' ";
           cmd = new SqlCommand(str, con);
           int temp = Convert.ToInt32(cmd.ExecuteScalar().ToString());
           SqlDataReader sdr = cmd.ExecuteReader();

the error pointer shows here-"con.open();"

And My web.config file is-<?xml version="1.0"?>



<configuration>
<connectionStrings>
<add name="NoveltySystemConnectionString" connectionString="Data Source=HOME-PC\SQLEXPRESS;Initial Catalog=NoveltySystem;Integrated Security=True;Pooling=False" providerName="System.Data.SqlClient"/>
</connectionStrings>
<system.web>
<compilation debug="true" targetFramework="4.5" />
</system.web>

</configuration>

Please anyone help me quick..Thankyou

What I have tried:

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.Data.Sql;
using System.Configuration;
using System.Data;

namespace NovletyShop
{
    public partial class Login : System.Web.UI.Page
    {
        String str;
        SqlConnection con;
        SqlCommand cmd;
        
       
        protected void Page_Load(object sender, EventArgs e)
        {
            SqlConnection con = new SqlConnection();
            var constring = ConfigurationManager.ConnectionStrings["NoveltySystemConnectionString"].ConnectionString;
           
            
        }

        protected void loginB_Click(object sender, EventArgs e)
        {

            con = new SqlConnection(str);
            con.Open();
            str = "Select count(*) from admin where UserName='" + (TextBox1.Text) + "' and Password='" + (TextBox2.Text) + "' ";
            cmd = new SqlCommand(str, con);
            int temp = Convert.ToInt32(cmd.ExecuteScalar().ToString());
            SqlDataReader sdr = cmd.ExecuteReader();
           
            con.Close();
            if (sdr.Read()) 
            {
                Session["User"] = TextBox1.Text;
                Response.Redirect("AdBooks.aspx");
            }
            else
            {
                Response.Write("<script>alert('Somting Wrong..');</script>");

            }
        }
    }
}

Posted 16-Jan-19 21:06pm

Member 14083059

Updated 16-Jan-19 23:28pm

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F-ES Sitecore · Answer 1 · 2019-01-16T22:56:00

In the load event you put the connecting string in "constring" but you use "str" when opening it, which is a string variable you haven't put anything in yet. Also you define constring in the load event so it isn't available outside of that event. Change the code to

namespace NovletyShop
{
    public partial class Login : System.Web.UI.Page
    {
        String str;
        String constring;
        SqlConnection con;
        SqlCommand cmd;
        
       
        protected void Page_Load(object sender, EventArgs e)
        {
            SqlConnection con = new SqlConnection();
            constring = ConfigurationManager.ConnectionStrings["NoveltySystemConnectionString"].ConnectionString;
           
            
        }

        protected void loginB_Click(object sender, EventArgs e)
        {

            con = new SqlConnection(constring);

OriginalGriff · Answer 2 · 2019-01-16T21:21:00

Check the actual string in the debugger: put a breakpoint on the line

con = new SqlConnection(str);

and look at exactly what str contains. At a guess, it's null or the empty string because the connection string read code hasn't been executed, or the web.config isn't what you think it is.
Either way, we can't check for you - it needs your code running to look at what is going on, and we can't do that for you - which means the debugger!

But don't do your code like that (particularly not in a web based system!)
Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Always use Parameterized queries instead.

When you concatenate strings, you cause problems because SQL receives commands like:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'Baker's Wood'

The quote the user added terminates the string as far as SQL is concerned and you get problems. But it could be worse. If I come along and type this instead: "x';DROP TABLE MyTable;--" Then SQL receives a very different command:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'x';DROP TABLE MyTable;--'

Which SQL sees as three separate commands:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'x';

A perfectly valid SELECT

SQL

DROP TABLE MyTable;

A perfectly valid "delete the table" command

SQL

--'

And everything else is a comment.
So it does: selects any matching rows, deletes the table from the DB, and ignores anything else.

So ALWAYS use parameterized queries! Or be prepared to restore your DB from backup frequently. You do take backups regularly, don't you?

And never store passwords in clear text - it is a major security risk. There is some information on how to do it here: Password Storage: How to do it.[^]

Dipesh Bagdi · Answer 3 · 2019-01-16T23:28:00

Well, in load event you are reading connection string from config in a local block variable constring , initialize your global variable str with connection sting.

partial class Login : System.Web.UI.Page
    {
        String str;
        SqlConnection con;
        SqlCommand cmd;        
       
        protected void Page_Load(object sender, EventArgs e)
        {
            SqlConnection con = new SqlConnection();
            str = ConfigurationManager.ConnectionStrings["NoveltySystemConnectionString"].ConnectionString;
}
protected void loginB_Click(object sender, EventArgs e)
        {

            con = new SqlConnection(str);
            con.Open();            
        }
    }

How to solve this-the connectionstring property has not been initialized.

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