'Object cannot be cast from dbnull to other types.'

Question

1.00/5 (1 vote)

See more:

I am getting issue while tab reach to next new row after loading data from data base to datagridview. Can anyone correct my code??

What I have tried:

C#

private void dataGridSALEITEM_CellValueChanged(object sender, DataGridViewCellEventArgs e)
    {
        decimal TOTALAMOUNT = 0;
        decimal TOTALCGST = 0;
        decimal TOTALSGST = 0;
        decimal NETTOTAL = 0;

        foreach (DataGridViewRow row in dataGridSALEITEM.Rows)
        {

            row.Cells[dataGridSALEITEM.Columns[7].Index].Value = (Convert.ToInt32(row.Cells[dataGridSALEITEM.Columns[3].Index].Value) * Convert.ToInt32(row.Cells[dataGridSALEITEM.Columns[4].Index].Value));

            row.Cells[dataGridSALEITEM.Columns[8].Index].Value = (Convert.ToInt32(row.Cells[dataGridSALEITEM.Columns[7].Index].Value) / 200 * Convert.ToInt32(row.Cells[dataGridSALEITEM.Columns[5].Index].Value));

            row.Cells[dataGridSALEITEM.Columns[9].Index].Value = (Convert.ToInt32(row.Cells[dataGridSALEITEM.Columns[7].Index].Value) / 200 * Convert.ToInt32(row.Cells[dataGridSALEITEM.Columns[5].Index].Value));

            row.Cells[dataGridSALEITEM.Columns[10].Index].Value = (Convert.ToInt32(row.Cells[dataGridSALEITEM.Columns[7].Index].Value) + Convert.ToInt32(row.Cells[dataGridSALEITEM.Columns[8].Index].Value) + Convert.ToInt32(row.Cells[dataGridSALEITEM.Columns[9].Index].Value));

            TOTALAMOUNT += Convert.ToDecimal(row.Cells[dataGridSALEITEM.Columns[7].Index].Value);
            TOTALCGST += Convert.ToDecimal(row.Cells[dataGridSALEITEM.Columns[8].Index].Value);
            TOTALSGST += Convert.ToDecimal(row.Cells[dataGridSALEITEM.Columns[9].Index].Value);
            NETTOTAL += Convert.ToDecimal(row.Cells[dataGridSALEITEM.Columns[10].Index].Value);
        }
        txtSUBTOTAL.Text = TOTALAMOUNT.ToString();
        txtCGST.Text = TOTALCGST.ToString();
        txtSGST.Text = TOTALSGST.ToString();
        txtGTOTAL.Text = NETTOTAL.ToString();
    }

Posted 13-Apr-20 9:13am

Member 14132181

Updated 13-Apr-20 9:34am

Add a Solution

2 solutions

Solution 1

You could try this:

foreach (DataGridViewRow row in dataGridSALEITEM.Rows)
{
  if (row != null)
  {
  ... your code
  }
}

If you still get errors, you should test the other values for null.
Also try stepping through your code after setting a breakpoint, e.g. on the line with the foreach statement.
You can inspect the values of variables by hovering over them with the mouse.

Posted 13-Apr-20 9:34am

RickZeeland

Updated 13-Apr-20 9:37am

v2

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Accepted Answer · 2020-04-13T09:35:00

It's going to depend on the data - which we have no access to - which part of that code is wrong, or your DB design needs improvement.

So, it's going to be up to you.
Fortunately, you have a tool available to you which will help you find out what is going on: the debugger. If you don't know how to use it then a quick Google for "Visual Studio debugger" should give you the info you need.

Somewhere in that code one or more of your DB columns contains a NULL value, which is returned as DBNull, and the system is complaining that you are trying to convert that to another type such as an integer - and integers can't contain NULL so it is absolutely right to do so.

Why is is NULL? Don't know - no access to your DB, remember - so the first thing to do is find out what value it is, then look at the whole row and work out if NULL is an appropriate value. If it is, then check for it and do what makes sense as a result. If it isn't, then work out how it got to be, what it should contain, and change your DB so it can't be NULL at all.

Put a breakpoint on the first line in the function, and run your code through the debugger. Then look at your code, and at your data and work out what should happen manually. Then single step each line checking that what you expected to happen is exactly what did. When it isn't, that's when you have a problem, and you can back-track (or run it again and look more closely) to find out why.

Sorry, but we can't do that for you - time for you to learn a new (and very, very useful) skill: debugging!