How do you read the vaue of a DataGridViewCheckBoxColumn ?

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Hi all;

I have a Windows form with a DataGridView control, and there are several columns of type DataGridViewCheckBoxColumn that I want to read (checked or unchecked). Everything is unbounded.

Now this of course should be the simplest thing, but something isn't working as it should. For example, I have a column called "Options", and I want to see if a particular row's "Options" checkbox is checked or not. Just for fun, read the value and display it in a message box:

I've tried

C#

if (dataGridView.Rows[dataGridView.CurrentCell.RowIndex].Cells[dataGridView.Columns["Options"].Index].Value  != null)
    {
        // Do some stuff
        MessageBox.Show(dataGridView.Rows[dataGridView.CurrentCell.RowIndex].Cells[dataGridView.Columns["Options"].Index].Value.ToString());
    }

and I've also tried

C#

DataGridViewCheckBoxCell cbox = new DataGridViewCheckBoxCell();
cbox = dataGridView.Rows[dataGridView.CurrentCell.RowIndex].Cells[dataGridView.Columns["Options"].Index];
if (cbox.Value  != null)
    {
        // Do some stuff
        MessageBox.Show(cbox.Value.ToString());
    }

Whenever I check or uncheck the box, the value is always

C#

null

and so the code to show the MessageBox never runs.

I know I'm missing something basic, but I can't see it. Why am I reading

C#

null

all the time, regardless of the checkbox state?

Posted 22-Mar-13 2:10am

Fortan_77

Updated 22-Mar-13 2:12am

Kenneth Haugland

v2

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Comments

josh-jw 22-Mar-13 8:26am

In which datagrid event you are calling this code block?

Fortan_77 22-Mar-13 8:28am

I'm using _CellContentClick

josh-jw 22-Mar-13 8:32am

check
if (e.RowIndex == -1)
then return ,otherwise do the functionality

josh-jw 22-Mar-13 8:34am

otherwise go for dataGridView1_CellClick event

2 solutions

Solution 1

I just tried your code:

C#

private void button1_Click(object sender, EventArgs e)
    {
    dgvData.Rows.Add(true);
    dgvData.Rows.Add(false);
    dgvData.Rows.Add(true);
    dgvData.Rows.Add(false);
    }


private void button2_Click(object sender, EventArgs e)
    {
    if (dgvData.Rows[dgvData.CurrentCell.RowIndex].Cells[dgvData.Columns["chkBox"].Index].Value != null)
        {
        // Do some stuff
        MessageBox.Show(dgvData.Rows[dgvData.CurrentCell.RowIndex].Cells[dgvData.Columns["chkBox"].Index].Value.ToString());
        }
    }

And all I get is "true" or "false", as I would expect.

Are you sure it is executing that code? Because you would not normally get a MessageBox - you would get a NullReferenceException as the value you are calling ToString on would have to be null - which won't work!

Posted 22-Mar-13 2:33am

OriginalGriff

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Rohit Kumar Mumbai · Accepted Answer · 2013-03-22T02:37:00

Solution 2

C#

private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
   DataGridViewCheckBoxCell checkbox = (DataGridViewCheckBoxCell)dataGrid_ModelControls.CurrentCell;

     bool isChecked = (bool)checkbox.EditedFormattedValue;

}

Try this ....

Posted 22-Mar-13 2:37am

Rohit Kumar Mumbai

Comments

Fortan_77 22-Mar-13 8:54am

Thanks Rohit; that works. For any cell I can now see the value:

DataGridViewCheckBoxCell checkbox = (DataGridViewCheckBoxCell)dataGridViewBookingDetails.CurrentCell;
bool isChecked = (bool)checkbox.EditedFormattedValue;
MessageBox.Show(isChecked.ToString ());

And OriginalGriff, yes it was executing the code... I tried the following:

if (dataGridView.Rows[dataGridView.CurrentCell.RowIndex].Cells[dataGridView.Columns["Options"].Index].Value == null)
dataGridView.Rows[dataGridView.CurrentCell.RowIndex].Cells[dataGridView.Columns["Options"].Index].Value = false;

MessageBox.Show(dataGridView.Rows[dataGridView.CurrentCell.RowIndex].Cells[dataGridView.Columns["Options"].Index].Value.ToString());

So yes Rohit's solution works, but I still don't know what was wrong with my original code.

Fortan_77 22-Mar-13 9:04am

Ah. Seems that the key is to use "EditedFormattedValue" and NOT "Value".

The following works perfectly:

if (dataGridView.Rows[dataGridView.CurrentCell.RowIndex].Cells[dataGridView.Columns["colOptionsCot"].Index].EditedFormattedValue != null)
MessageBox.Show(dataGridView.Rows[dataGridView.CurrentCell.RowIndex].Cells[dataGridView.Columns["Options"].Index].EditedFormattedValue.ToString());

On the other hand, this falls over with the NullReferenceException that OriginalGriff mentioned above:

if (dataGridView.Rows[dataGridView.CurrentCell.RowIndex].Cells[dataGridView.Columns["colOptionsCot"].Index].Value != null)
MessageBox.Show(dataGridView.Rows[dataGridView.CurrentCell.RowIndex].Cells[dataGridView.Columns["Options"].Index].Value.ToString());

Rohit Kumar Mumbai 22-Mar-13 9:10am

Ya Fortran_77 you are right. hope it solves your query .

Cheers Mate.