system.null reference exception

Question

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i m getting the following error in the line
"con = new SqlConnection(ConfigurationManager.ConnectionStrings["Connect"].ToString());" of code below...

Error:
"system.nullreferenceexception object reference not set to an instance of an object."

C#

public partial class _Default : System.Web.UI.Page
{
    SqlDataAdapter da;
    DataSet ds = new DataSet();
    SqlCommand cmd = new SqlCommand();
    SqlConnection con;
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            BindData();
        }
    }
    public void BindData()
    {
        con = new SqlConnection(ConfigurationManager.ConnectionStrings["Connect"].ToString());//getting error in this line
        cmd = new SqlCommand("Select * from b_asset_master", con);
        cmd.Connection = con;
        da = new SqlDataAdapter(cmd);
        da.Fill(ds);
        con.Open();
        cmd.ExecuteNonQuery();
        Grid.DataSource = ds;
        Grid.DataBind();
        con.Close();
    }
    protected void Grid_PageIndexChanged(object source, DataGridPageChangedEventArgs e)
    {
        Grid.CurrentPageIndex = e.NewPageIndex;
        BindData();
    }
}

Posted 24-Jun-13 20:29pm

dimtdj

Updated 24-Jun-13 23:56pm

v7

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Comments

Sergey Alexandrovich Kryukov 25-Jun-13 2:31am

In what line?
—SA

Prasad_Kulkarni 25-Jun-13 2:32am

Which line exactly? Obviously some value is unset, but without knowing which one it's impossible to say why the error is occurring.

Orcun Iyigun 25-Jun-13 2:32am

In which line you get the exception. Specify it.

dimtdj 25-Jun-13 2:33am

da.Fill(ds);

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MuhammadUSman1 · Answer 1 · 2013-06-25T00:13:00

C#

con = new SqlConnection(ConfigurationManager.ConnectionStrings["Connect"].ToString());//getting error in this line

in this line you are using

C#

ConfigurationManager.ConnectionStrings["Connect"].ToString()

but i think "Connect" key dose not exist in your config file. or you using wrong spell there.

OriginalGriff · Answer 2 · 2013-06-24T20:36:00

Solution 1

It depends which line it is on, really, but the most obvious candidate is:

C#

cmd.CommandText = "Select * from b_asset_master";

If you have not assigned a value to cmd, then you will get this error.
Try changing it to:

C#

cmd = new SqlCommand("Select * from b_asset_master", con);

and discard the line after it. The problem should go away.

When you get a problem like this, the first thing to do is look at the code in the debugger, and find the variable that is null - you can usually work out pretty easily from that what you need to do. And it's a lot, lot quicker than asking here each time! :laugh:

Posted 24-Jun-13 20:36pm

OriginalGriff

Comments

dimtdj 25-Jun-13 2:52am

thanks for your concern but it doesn't help me

OriginalGriff 25-Jun-13 3:11am

So what happened when you debugged it?

dimtdj 25-Jun-13 5:24am

it is saying that "The ConnectionString property has not been initialized."

OriginalGriff 25-Jun-13 5:39am

I think you missed something - can you post the exact code that gives the current error?

dimtdj 25-Jun-13 5:42am

i have update the question... now it contain the whole code...

OriginalGriff 25-Jun-13 5:48am

Which is unchanged from the code I said to alter...

dimtdj 25-Jun-13 5:50am

i have done alteration same error is there

OriginalGriff 25-Jun-13 5:51am

So show the version as altered, that gives you the new error message - not the old one.

dimtdj 25-Jun-13 5:52am

it is giving the same error...

OriginalGriff 25-Jun-13 5:57am

Quote: "it is saying that "The ConnectionString property has not been initialized.""
That is not the same error as "system.nullreferenceexception object reference not set to an instance of an object"

Bernhard Hiller · Answer 3 · 2013-06-24T20:55:00

Solution 2

Where does that ds come from? Looks like that is null.

Posted 24-Jun-13 20:55pm

Bernhard Hiller

Comments

dimtdj 25-Jun-13 2:58am

SqlDataAdapter da;
DataSet ds = new DataSet();
SqlCommand cmd = new SqlCommand();
SqlConnection con;

from the above code... its is written in "class _Default" before page load event

Akmal Abbas Naqvi · Answer 4 · 2013-06-24T23:57:00

Solution 3

Hi!
Open your connection like this.

SqlConnection myConnection = new SqlConnection();
myConnection.ConnectionString = Cls_connection;
myConnection.Open();

Posted 24-Jun-13 23:57pm

Akmal Abbas Naqvi

Comments

Akmal Abbas Naqvi 25-Jun-13 5:59am

Or Remove the toString() part from connectionstring line
Hope this will help

system.null reference exception

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