Question

Friends
I had a datagridview in my windowsdesktop application to insert data into the database. when i click the add button validation should be done to ensure that no cells are left empty .I am not using cellvalidatorevent since i think its complicating process
i had written code like this

public void validateDatagrid()
        {
            if (tblpurchaserequest.RowCount == 1)
            {
                lblstatus.Text = "There is No  Purchase Data to Add";

            }
            else
            {
                for (int i = 0; i < tblpurchaserequest.RowCount; i++)
                {



                    if (tblpurchaserequest.Rows[i].Cells[0].Value.ToString().Trim() == "" || tblpurchaserequest.Rows[i].Cells[1].Value == null)
                    {
                        lblstatus.Text = "Please Enter Item in " + i + "th ROW";
                    }

                    if (tblpurchaserequest.Rows[i].Cells[0].Value.ToString().Trim() == "" || tblpurchaserequest.Rows[i].Cells[2].Value == null)
                    {
                        lblstatus.Text = "Please Enter Description in " + i + "th ROW";
                    }
                    if (tblpurchaserequest.Rows[i].Cells[0].Value.ToString().Trim() == "" || tblpurchaserequest.Rows[i].Cells[3].Value == null)
                    {
                        lblstatus.Text = "Please Enter Supplier in " + i + "th ROW";
                    }
                    if (tblpurchaserequest.Rows[i].Cells[0].Value.ToString().Trim() == "" || tblpurchaserequest.Rows[i].Cells[4].Value == null)
                    {
                        lblstatus.Text = "Please EnterQuantity in " + i + "th ROW";
                    }
                }
            }

        }

but this is giving exception
Object reference not set to an instance of an object.
pls advice me my mistake

Answer 1

Obviously some value is null and the way you do the check in your if clause would need to be in a different order.

Change from:

if (tblpurchaserequest.Rows[i].Cells[0].Value.ToString().Trim() == "" 
    || tblpurchaserequest.Rows[i].Cells[1].Value == null) 

to:

if (tblpurchaserequest.Rows[i].Cells[1].Value == null
    || tblpurchaserequest.Rows[i].Cells[0].Value.ToString().Trim() == "") 

That is, check for NULL first. This will ensure that the second part in your if does not get evaluated, if the first part indeed returns a null (which is giving you an “object reference blah blah” error)

You will need to reverse the order on all if statements in your code block.