C# Error 'Object Reference Not Set To An Instance Of An Object'

Question

I've read other questions about this but don't see where or why my code is throwing this error. The code I have is below, if anyone can see where i'm going wrong.

    private void btnSignIn_Click(object sender, EventArgs e)
    {
        sqlConnectionNW.ConnectionString = "Data Source=" + server + ";Initial Catalog=Northwind;Integrated Security=True";
        try
        {
            sqlConnectionNW.Open();
            String enteredDate = cmbDay.SelectedItem.ToString() + "/" + cmbMonth.SelectedItem.ToString() + "/" + cmbYear.SelectedItem.ToString();

            if ((txtEmployeeID.TextLength != 0) && (enteredDate.Length != 0))
            {
                int ID = Convert.ToInt32(txtEmployeeID.Text);
                employeesBindingSource.Filter = "EmployeeID ='" + txtEmployeeID.Text + "'";
                String birthDate;
                birthDate = dsEmployees.Employees.FindByEmployeeID(ID).BirthDate.ToShortDateString();

                if (employeesBindingSource.Count > 0)   //GETS TO HERE AND THEN GOES TO CATCH EX
                {
                    sqlConnectionNW.Close();
                    if (enteredDate.ToString() == birthDate.ToString())
                    {
                        frmMenu frmMainMenu = new frmMenu();
                        frmMainMenu.server = server;
                        frmMainMenu.employeeID = txtEmployeeID.Text;
                        MessageBox.Show("Welcome to the Northwind Ordering System");
                        this.Hide();
                        frmMainMenu.Show();
                    }
                    else
                    {
                        MessageBox.Show("The birth date you have entered is incorrect");
                    }
                }
                else
                {
                    MessageBox.Show("The Employee ID you have entered does not exist");
                }
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
        sqlConnectionNW.Close();
    }

Can you post the stack trace? Do you know which line is throwing the error? — Andy, Mar 25 '11 at 01:16
@Jon, how is the compiler going to help in finding the cause of a runtime exception? — Kirk Woll, Mar 25 '11 at 01:19
@Kirk: My bad. For some reason was thinking exception message (=stack trace) and converted that to compiler error message. Sorry :) — Jon, Mar 25 '11 at 01:21
@Kimmy, that line could not possibly have been the direct cause of this, since the only candidate for an NRE (`employeesBindingSource`) was dereferenced earlier. Thus, what is `employeesBindingSource` to begin with? Possibly the implementation of `Count` is throwing the error. Can you please post the entire stack trace? — Kirk Woll, Mar 25 '11 at 01:25
@Kimmy25 Can you please post how you define/initialise the variable "employeesBindingSource". — Jamie Keeling, Mar 25 '11 at 01:32
This may sounds strange but nothing appears in the Call Stack window :S — 6TTW014, Mar 25 '11 at 01:34
I just added it to the Windows Form and connected it etc in the properties window. — 6TTW014, Mar 25 '11 at 01:36
@Kimmy25 So are you saying the employeesBindingSource is a component? (Dragged from the Toolbox onto the Design window?) — Jamie Keeling, Mar 25 '11 at 01:39
Can't you put a breakpoint at the first line of that method and then single-step to see exactly where the error occurs? Before executing each line, use the debugger to examine every variable that will be used. I think you'll find the error fairly quickly that way. — Jim Mischel, Mar 25 '11 at 02:25

score 2 · Answer 1 · answered Mar 25 '11 at 12:18

Manage to solve this problem. I changed this:

if ((txtEmployeeID.TextLength != 0) && (enteredDate.Length != 0))
            {

                int ID = Convert.ToInt32(txtEmployeeID.Text);

                employeesBindingSource.Filter = "EmployeeID ='" + txtEmployeeID.Text + "'";

                String birthDate;

                birthDate = dsEmployees.Employees.FindByEmployeeID(ID).BirthDate.ToShortDateString();    // FROM HERE

                if (employeesBindingSource.Count != 0)
                {

                    sqlConnectionNW.Close();

To this:

if ((txtEmployeeID.TextLength != 0) && (enteredDate.Length != 0)) {

                int ID = Convert.ToInt32(txtEmployeeID.Text);

                employeesBindingSource.Filter = "EmployeeID ='" + txtEmployeeID.Text + "'";

                String birthDate;

                if (employeesBindingSource.Count != 0)
                {
                    birthDate = dsEmployees.Employees.FindByEmployeeID(ID).BirthDate.ToShortDateString();    //TO HERE

                    sqlConnectionNW.Close();

It was just a case of putting the "birthDate = ..." after the if statement.

C# Error 'Object Reference Not Set To An Instance Of An Object'

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