Row Deleting event in gridview control.

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i am trying to delete userid and groupid from the roles table on selecting userid from the user table in the gridview control. i am getting and error that. can anyone figure out wots the problem in query.

Object reference not set to an instance of an object.

C#

protected void _rowdeleting(object sender, GridViewDeleteEventArgs e)
   {
       GridViewRow row = (GridViewRow)GridView1.Rows[e.RowIndex];
       Label lbldeletename = (Label)row.FindControl("lblusername");
       TextBox textname = (TextBox)row.FindControl("txtusername");
       MAconn.Open();
       SqlCommand cmd = new SqlCommand("Delete From ROLES (UserId,GroupId) SELECT UserId FROM Users WHERE username= '" + textname.Text + "'", MAconn);
       cmd.ExecuteNonQuery();
       MAconn.Close();
       bind();

   }

Posted 9-Sep-11 0:58am

codegeekalpha

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Comments

Prerak Patel 9-Sep-11 7:00am

Debug step by step and check if anything is null.

3 solutions

Solution 2

Check this[^]

Posted 9-Sep-11 1:04am

Syed Salman Raza Zaidi

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Simon Bang Terkildsen 9-Sep-11 7:06am

The problem isn't how to use the event. The problem is the code in the event handler.

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Simon Bang Terkildsen · Accepted Answer · 2011-09-09T01:03:00

lbldeletename, textname or MAconn is most likely null, as Prerak suggests use the debugger to the exact reason.
Have a look at Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[^]

I just noticed you're not even using lbldeletename that leaves textname or MAconn as the possible source of your exception.

Mohd Wasif · Accepted Answer · 2011-09-09T01:17:00

I will like to advise to set username as DataKey of Gridview

and do coding something like it.

C#

protected void _rowdeleting(object sender, GridViewDeleteEventArgs e)
    {
         string username= GrdView1.DataKeys[e.RowIndex].Value.ToString();
        MAconn.Open();
        SqlCommand cmd = new SqlCommand("Delete From ROLES (UserId,GroupId) SELECT UserId FROM Users WHERE username= @username", MAconn);
          cmd .Parameters.AddWithValue("@username",username);
        cmd.ExecuteNonQuery();
        MAconn.Close();
        bind();
 
    }

Row Deleting event in gridview control.

3 solutions

Solution 1

Solution 3

Solution 2

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